Low filtration of soils lying under the soil is the cause of excess water in the area. It slowly goes into the lower layers or does not seep at all. Cultivated plants grow poorly here or do not take root at all, the territory becomes swampy, slush is felt. In such cases, a drainage system is needed, which should be properly organized.

We will explain in detail how to make a site drainage project. A system arranged according to our advice will perfectly cope with its duties. Acquaintance with the proposed information will be useful for both independent owners and customers of landscape arrangement in a specialized company.

We have presented practical schemes for the construction of drainage systems for suburban areas. The article describes in detail the factors that need to be taken into account in the design and construction of drainage. The information proposed for consideration is illustrated with photographs, diagrams, and videos.

Land reclamation activities, in accordance with the norms (SNiP 2.06.15), are carried out in forest and agricultural lands so that the soil becomes as suitable as possible for growing fruit trees, cereals and vegetables.

For this, an extensive system of open ditches or closed pipelines is formed, the main purpose of which is to drain overly wet areas.

The ultimate goal of collecting water through branches and sleeves of various types is artificial or natural reservoirs (if conditions permit), special drainage ditches, or storage tanks from which water is pumped out for irrigation and maintenance of the territory.

Often, pipes buried in the ground, if the relief allows, are replaced by external structures - ditches and trenches. These are open-type drainage elements, through which water moves by gravity.

According to the same principle, a pipeline network is designed for a summer cottage, regardless of its area - 6 or 26 acres. If the area suffers from frequent flooding after rain or spring floods, the construction of catchment facilities is mandatory.

Accumulation of excess moisture is facilitated by clay soils: sandy loam and loam, because they do not pass or very weakly pass water into the underlying layers.

Another factor that encourages thinking about a drainage project is the elevated level of groundwater, the presence of which can be found out even without special geological surveys.

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Excess moisture in the soil is always a danger to the integrity of the foundation of construction projects: houses, baths, garages, outbuildings

Elements of the drainage structure

What is a drainage system? This is a network consisting of various components, the main purpose of which is the removal and collection of capillary water contained in the pores of non-cohesive soils and cracks in cohesive rocks.

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The diversion of groundwater, including flood water, from buildings and soil on the site is one of the most frequent hydrogeological tasks. However, before proceeding with its solution, it is necessary to determine the required throughput of the sewer, and for this, a drainage calculation will be required. How to perform it, what factors are taken into account, and what are the groundwater drainage systems - later in the article.

Attention! It should be taken into account that, depending on the specific conditions, when laying the ring drainage, the distance between the trench wall in its upper part and the wall / foundation of the house should be at least 3 m. The filler (gravel and sand) should be backfilled to such a depth as to prevent swelling of the soil when water freezes around the foundation. We should not forget about the mandatory organization of a concrete blind area under the walls, extending at a distance of at least 1 mot of the building.

Ways to organize drainage

It could be:

• simple backfilling of the trench with sand and gravel
• installation of drainage trays
• installation of drainage pipes
• installation of drainage mats

Sand and gravel backfill is attractive for its simplicity, for it it is enough to dig a trench and add filler with a layer of 15-40 cm. As a rule, the rest of the volume is filled from above with previously excavated soil.

But such rather quickly (within 2-3, maximum - 5 years) lose their effectiveness as a result of silting. Filling the space between the aggregate grains does not allow water to flow into the drain.

In the trench, also on a gravel-sand base, concrete or polymer concrete trays can be laid, which are covered on top, for example, with cast-iron gratings. This method is used, as a rule, near garden paths, transport entrances and similar objects.

The most common method now is the laying of drains - a special smooth-walled or corrugated perforated pipe. The advantage of this method is that with proper organization, especially with the use of geotextiles (for wrapping pipes), it ensures a long and reliable operation of the system.

Drainage mats are a three-layer material made from a combination of polymers, which have a high drainage capacity even under high ground pressure.

Mats are laid either in ordinary trays or trenches, or directly on the soil surface, which is used in large and excessively wet areas. In addition to high drainage capacity, mats also create a frost-protective layer that prevents soil heaving.

All these methods are applicable both for the organization of the removal of groundwater from the foundation of the building, and for the drainage of the territory of the land plot itself.

The calculation method was compiled only for gravity-flowing types of horizontal drainage.

Drainage pipes of these types of drainage, as a rule, are laid in free-flowing aquifers at a shallow depth (up to 8 m) and serve to lower the groundwater level.

According to the nature of the hydrodynamic impact and the degree of opening of the drained aquifer, drainages of a perfect or imperfect type are distinguished.

Horizontal drainages of the perfect type completely open the aquifers and reach the aquiclude with their base. Horizontal drainages of an imperfect type open the reservoir only partially and do not reach the aquiclude with their base.

Depending on the layout of drainage devices in relation to the protected area and to the sources of drainage water supply to them, the following underground drainage systems used in industrial and urban construction can be distinguished:

single line;

two-line;

ring (contour);

areal (systematic drainage).

Depending on the layout of the drainage, a method for calculating the water inflow is adopted.

Water inflow to drainage of perfect and imperfect types

To determine the flow rate of single-line horizontal drains of a perfect type (Fig. 1) with a length L (m), on the one hand, the Dupuis formula is used:

where: - water inflow to the drain on one side, / day;

Filtration coefficient, m/day;

The water depth in the drain can be taken equal to zero (in comparison with the first term, it has little effect on the result of the calculation);

Aquifer thickness (static depth of groundwater in the aquifer), m;

The length (radius) of the influence of the drain (at a distance R from the drain, the natural level of groundwater practically does not decrease).

Under conditions of variable supply of the exploited reservoir, the value of R also changes under conditions of unsteady movement of groundwater. Its value can be reliably determined empirically, which requires significant survey and exploration work.

This length can be established on the basis of hydrological survey data through the average slope of the depression curve:

The amount of slope depends on the properties of the soil. So for the most permeable (gravel-sand) soils = 0.003 - 0.006;

for sands = 0.02 - 0.05;

for loams = 0.05 - 0.1;

for clay = 0.1 - 0.15;

for heavy clays = 0.15 - 0.2.

Tentatively, the length of the radius of influence is sometimes assigned according to practice, depending on the type of soil (Table 5).

Table 5

Radius of influence r and coefficients of water loss

Type of aquifer	Particle diameter, mm
loams
The sand is fine
Sand medium
The sand is coarse
gravelly sand
fine gravel
Limestones
Sandstones

The radius of influence or, more precisely, the unsteady width of the zone of influence of long linear drainage systems can be approximately determined by the formulas:

during the drawdown of static groundwater reserves, i.e. in the absence of infiltration:

in the presence of infiltration:

where is the water yield of drained soils, can be taken according to Table 5;

Duration of the drain operation period, days;

Infiltration coefficient, m/day, equal to

The amount of precipitation falling in the given area, mm;

Soil porosity (infiltration) coefficient, usually taken as .

The approximate value can be taken from 0.00246 m/day. in the old districts of the city and up to 0.00129 m/day. - in new areas and suburbs.

Approximately the value of the radius of influence in loose (sandy) soils can be calculated by the formula:

When water flows through a poorly permeable roof or sole, the conditional radius of influence of drainage should be determined by the formula:

, (10)

where and are, respectively, the power and filtration coefficient in the roof or bottom of low-permeability soils;

The same main layer from which water is taken.

For the conditions of the location of the drainage in the sands and peats underlain by sands, the value is assumed to be 50 m.

With inflow from both sides, the flow rate calculated by formula (6) doubles.

To determine the flow rate of imperfect drains (Fig. 2), the following formula can be used:

, (11)

where is the lowering of the groundwater level above the drain, m; can be accepted;

Half the width of the drain, equal to the radius of the drainage pipe;

Distance from the bottom of the drainage to the aquiclude.

With a symmetrical water inflow to the drain, formula (11) is simplified:

. (12)

Water inflow to a two-line horizontal drainage

The flow rate of two-line horizontal drains of the perfect type is determined by the Dupuis formulas:

. (13)

The level of groundwater between two drains after the formation of depression funnels is set approximately at the water levels in the drains themselves.

The flow rate of a two-line horizontal drainage of an imperfect type and its symmetrical location with respect to the supply area:

,

where is the distance between the rows of drains, m;

Drainage radius, m

Water inflow to ring, platform (systematic) and reservoir horizontal drainages

Ring drains include horizontal drains, usually consisting of tubular drains located along the contours of the protected area.

Complex contours of real drainages are reduced to an equal circle with a reduced radius , to determine the inflow of water to which there are already analytical solutions.

The total flow rate of ring drainages of the perfect type in non-pressure conditions is determined by the Dupuis formula:

, (15)

where is the total flow rate of drainage, / day;

So far, design organizations,implement l responsible for the design of drainage systems (hereinafter referred to as drains) in the city of Moscow, are guided by the "Temporary guidelines for the design of drainage in the city of Moscow ve (N M-15-69) " developed in 1969 "Mosproe who m-1" and "Mosinzhproe who m-1".

During the practical use of the "Temporary Directives", new designs of drainages have appeared, based on the use of modern materials, both positive and negative experience in the design and construction of drainages has been accumulated, which necessitates the development of a new regulatory document.

Application area

The "Guide" is intended for use in the design and construction of drainage of buildings, structures and underground utility channels located in residential areas, as well as for stand-alone buildings and structures.

The “Guidelines” do not apply to the design of shallow road drainages, transport and other special-purpose structures, as well as to temporary dewatering during construction work.

a common part

To protect the buried parts of buildings (basements, technical undergrounds, pits, etc.),morning quarterly x collectors, communication channels from flooding with groundwater should provide at sya drainage and. Kon s drainage and waterproofing of the underground part of buildings and structures must be carried out in accordance with SNiP 2.06.15-85,SNiP 2.02.01-83*,MGSN 2.07-97, "Recommendations for the design of waterproofing of underground parts of buildings and structures", developed by TsNIIPpromzdaniy in 1996year and the requirements of this Guide.

Drainage design should be carried out on the basis of specific data on the hydrogeological conditions of the facility construction site, the degree of groundwater aggressiveness to building structures, space-planning and design solutions for protected buildings and structures, as well as the functional purpose of these premises.

prot And capillary waterproofing in walls and coating or paint insulation of vertical wall surfaces,in contact with the ground, should be provided in all cases, regardless of the drainage arrangement.

The device of drainages is obligatory in cases of location :

basement floors ,technical subfields, ext mornings and quarterly x collectors, communication channels, etc. below the calculated groundwater level or if the excess of floors above the calculated groundwater level is less than 50 cm;

floors of operated basements, intra-quarter collectors, communication channels in clay and loamy soils, regardless of the presencei groundwater;

floors of basements located in the zone of capillary moistening, when in the basements it is not allowed to see s grow;

floors of technical undergrounds in clay and loamy soils when they are buried more than 1, 3m from the planning surface of the earth, regardless of the presence of groundwater;

floors of technical undergrounds in clay and loamy soils when they are buried less than 1, 3m from the planning surface of the earth when the floor is located on the foundation slab, as well as in cases where sand lenses approach the building from the upland side or a thalweg is located from the upland side of the building.

In order to exclude watering of the soils of the territories and the flow of water to buildings and structures, in addition to drainage, it is necessary to provide for:

normative soil compaction when backfilling pits and trenches;

as a rule, closed outlets of drains from the roof of buildings;

drainage SCH no open trays≥15×15 see longitudinal slope,≥1% with open drainage outlets;

blind area for buildings wide≥100see with active cross slope from buildings≥2% to roads or trays;

hermetic sealing of openings in external walls and foundations at the inlets and outlets of engineering networks;

organized surface runoff from the territory of the facility being designed, which does not impair the removal of rain and melt water from the adjacent territory.

In cases where, due to the low elevations of the existing surface of the earth, it is not possible to ensure the drainage of surface water or achieve the required lowering of groundwater, the area should be backfilled to the required elevations. If gravity drainage of drainage waters from individual buildings and structures or a group of buildings is not possible, provision should be made for the installation of pumping stations for pumping drainage waters.

The design of the drainage of new facilities should be carried out taking into account the existing or previously designed drainages of the adjacent territories. th.

With a general decrease in the level of groundwater in the territory of the microdistrict, the marks of the lowered level of groundwater should be assigned to 0, 5m below the floors of cellars, technical undergrounds, communication channels and other structures. In case of impossibility or inexpediency of a general lowering of the groundwater level, local drainage should be provided for individual buildings and structures (or groups of buildings).).

Local drainage, as a rule, should be arranged in cases of significant deepening of underground floors separatelys x buildings when gravity removal of drainage water is not possible.

Types of drains

Depending on the location of the drainage in relation to the aquiclude, the drainages can be of a perfect or imperfect type.

Drainage of the perfect type is laid on the aquiclude. Groundwater enters the drainage from above and from the sides. In accordance with these conditions, a drainage of a perfect type must have a draining coating on top and sides (see Fig.).

Drainage of an imperfect type is laid above the aquiclude. Groundwater enters the drains from all sides, so drainage backfilling must be carried outh enclosed on all sides (see fig.).

Initial data for drainage design

To draw up a drainage project, the following data and materials are required:

technical opinion on the hydrogeological conditions of construction;

scale plan of the area 1: 500with existing and planned buildings and underground structures;

relief organization project;

plans and marks of floors of basements and subfloors of buildings;

plans, sections and developments of building foundations;

plans ,longitudinal profiles and sections of underground channels.

In the technical report on the hydrogeological conditions of construction, the characteristics of groundwater, geoloG o-lithological structure of the site and physical and mechanical properties of soils.

In the groundwater characteristics section, the following should be indicated:

reasons for the formation and sources of groundwater supply;

groundwater regime and marks of the appeared, established and calculated levels of groundwater, and, if necessary, the height of the zone of capillary moistening of the soil;

chemical analysis data and a conclusion on the aggressiveness of groundwater in relation to concrete and mortar but m.

The geological and lithological section provides a general description of the structure of the site.

In the characteristics of the physical and mechanical properties of soils, the following should be indicated:

granulometric composition of sandy soils;

filtration coefficients of sandy soils and sandy loams;

porosity and water loss coefficients;

angle of repose and soil bearing capacity.

The conclusion should be accompanied by the main geological sections and "columns" of soils from boreholes, necessary for compiling geological sections along the drainage routes.

If necessary, in difficult hydrogeological conditions for drainage projects for blocks and microdistricts, a map of hydroisogypsum and a map of soil distribution should be attached to the technical report.

In the case of special requirements for the drainage device, caused by the specific operating conditions of the protected premises and structures, these requirements must be stated by the customer as additional source materials for the design of drainage.

General conditions for choosing a drainage system

The drainage system is selected depending on the nature of the protected object and hydrogeological conditions.

When designing new quarters and microdistricts in areas with a high level of groundwater, a general drainage scheme should be developed.

The drainage scheme includes drainage systems,providing a general decrease in the level of groundwater in the territory of a quarter (microdistrict), and local drainage to protect individual structures from flooding by groundwater th.

Drainages that provide a general decrease in the level of groundwater include drainage:

head or coastal;

systematically i.

Local drainages include drainages:

annular;

wall-mounted;

formations th.

Local drains also include drains intended forh protection of individual structures:

drainage of underground channels;

pit drainage;

road drainage;

drainage of filled rivers, streams, ravines and ravines;

sloping and slanted s and drainage;

drainage of underground parts of existing buildings.

Under favorable conditions (in sandy soils, as well as in sandy interlayers with a large area of ​​​​their distribution), local drainage can simultaneously contribute to a general decrease in the level of groundwater.

In areas where groundwater occurs in sandy soils,drainage systems should be used to ensure a general lowering of the groundwater level.

In this case, local drainages should be used to protect certain especially buried structures from flooding by groundwater.

In areas where groundwater occurs in clayey, loamy and other soils with low water loss, it is necessary to arrange local drainage And.

Local “preventive” drainages should also be arranged in the absence of observed groundwater to protect underground structures locatedl aged in clay and loamy soils.

In areas with a layered structure of the aquifer, both general drainage systems and local drainage should be arranged.

General drainage systems should be arranged to drain flooded sand layers through which water enters the drained area. In this system, separate local drainages can also be used, in which the depression radiusn curve covers a significant area of ​​the territory. Local drainage must be arranged for underground structures laid in areas where the aquifer is not completely drained by the general drainage system, as well as in places h the possible appearance of a top water.

In built-up areas, during the construction of individual buildings and structures that need protection from groundwater flooding, local drainage should be arranged. When designing and constructing these drains, consideration must be given to their impact on adjacent existing structures.

head drainage

To drain the territories flooded by the flow of groundwater with a supply area located outside this territory, head drainage should be arranged (see Fig.).

The head drainage should be laid along the upper, in relation to the underground flow, boundary of the drained territories. The drainage route is assigned taking into account the location of the building and is carried out, if possible, in places with higher elevations during d support.

The head drainage should, as a rule, cross the groundwater flow along its entire width.

If the length of the head drainage is less than the width of the underground flow, additional drains should be installed along the lateral boundaries of the drained area in order to intercept groundwater entering from the side.

When the aquiclude is shallow, the head drainage should be laid on the surface of the aquiclude (with some penetration into it) in order to completely intercept groundwater, as a drainage of a perfect type.

In cases where it is not possible to lay drainage on the aquiclude, and according to the conditions of drainage it is required to completely intercept the flow of groundwater, a screen from a waterproof sheet pile is arranged below the drainage, which must be lowered below the aquiclude marks.

When the aquiclude is deep, the head drainage is laid above the aquiclude, as an imperfect type of drainage. In this case, it is necessary to calculate the depression curve. If the device of one line of the main drainage does not achieve a decrease in the level of groundwater to the specified levels, a second drainage line should be laid parallel to the head drainage. The distance between the drains is determined by calculation.

If the part of the aquifer located above the drainage consists of sandy soils with a filtration coefficient less than 5m /s ut ki, the lower part of the drainage trench should be covered with sand with a filtration coefficient of at least 5 m / day (see fig.).

The sanding height is 0,6 - 0,7H, where: H is the height from the bottom of the drainage trench to the unreduced calculated groundwater level.

With a layered structure of a part of the aquifer located above the drainage, with alternating layers of sand and loam, backfilling the drainage trench with sand with a filtration coefficient of at least5m / day should be produced on 30see above for undecreased design groundwater level.

Backfilling with sand can be carried out over the entire width of the vertical trenchl with a prism or inclined prism, with a thickness of at least 30see For the head drainage of a perfect type, when the aquifer does not have clay, loamy and sandy layers, a sandy prism can be arranged only on one side of the trench (from the side of the inflow of water).

If the head drainage is laid in the thickness of relatively poorly permeable soils underlain by well permeable soils, a combined drainage should be arranged, consisting of a horizontal drain and vertical self-flowing wells (see Fig.).

Vertical wells must communicate with their base with the permeable soils of the aquifer, and the upper part with the inner layer of horizontal drain sprinkling.

For drainage of coastal areas flooded due to the backwater of the water horizon in rivers and reservoirs,coastal drainage should be arranged (see fig.), where the symbols are: M G - low-water horizon of the reservoir, G P B - the horizon of backed waters of the reservoir.

Coastal drainage is laid parallel to the shore of the reservoir and is laid below the normally supported horizon (NP D) a reservoir by a value determined by calculation.

If necessary, head and bank drainage can be used in combination with other drainage systems.

Systematic drainage

In areas where groundwater does not have a clearly defined flow direction, and the aquifer is composed of sandy soils or has a layered structure with open sandy interlayers, systematic drainage should be arranged (see Fig.).

The distance between the drainage drains of systematic drainage and the depth of their laying are determined by calculation.

In urban areas, systematic drainage can be arranged in combination with local drainages. In this case, when designing individual drains, one should consider the possibility of their onein temporary use as a local drainage that protects individual structures and as elements of a systematic drainage that provides a general decrease in the level of groundwater in the drained area.

When laying drains of systematic drainage in the thickness of soil with low water permeability, underlain by well permeable soils, combined drainage should be used, consisting of horizontal drains with vertical,self-flowing wells (see fig.).

In territories flooded by the flow of groundwater, the supply area of ​​\u200b\u200bwhich also captures the drained territory, head and systematic drainage should be used together.

ring drainage

To protect basements and subfloors of detached buildings or a group of buildings from flooding with groundwater, when they are laid in aquiferous sandy soils, ring drainage should be arranged (see Fig.).

Ring drainage should also be arranged to protect especially ruined basements in new quarters and microdistricts with an insufficient depth of lowering the groundwater level by the general drainage system of the territory.

With good water permeability of sandy soils, as well as when laying drainage on an aquiclude,it is possible to arrange a common ring drainage for a group of neighboring buildings.

With a clearly expressed unilateral inflow of groundwater, drainage can be arranged in the form of an openl ets by the type of head drainage.

Ring drainage should be laid below the floor of the protected structure to a depth,determined by calculation.

With a large width of the building or when protecting several buildings with one drainage, as well as in the case of special requirements for lowering groundwater under the protected structure, the depth of the drainage is taken in accordance with the calculation, in which the excess of the lowered groundwater level in the center of the ring drainage contour should be determined above the water level in the drain. If the drainage depth is insufficient, intermediate “cut” drains should be arranged.

Ring drainage should be laid at a distance 5 - 8m from the wall of the building. With a shorter distance or a large depth of drainage, it is necessary to take measures against the removal,weakening and settlement of the soil under the foundation of the building I

wall drainage

To protect basements and underground buildings laid in clay and loamy soils from groundwater, wall drainage should be arranged.

Wall "preventive" drainages must also be arranged in the absence of groundwater in the area of ​​​​basements and undergrounds, arranged in clay and loamy soils.

With a layered structure of the aquifer, wall or ring drainage should be arranged to protect the basements and underfloors of buildings, depending on local conditions.

If individual parts of the building are located in areas with different geological conditions, these areas can be used as an annular,and wall drainage.

Wall drainage is laid along the contour of the building from the outsides. The distance between the drainage and the building wall is determined by the width of the building foundations and the location of the drainage manholes.

Wall drainage, as a rule, should be laid at elevations not lower than the sole of the strip foundation or the base of the foundation slabs s.

With a large depth of foundations from the level of the basement floor, wall drainage can be laid above the base of the foundations, provided that measures are taken to prevent drainage from subsidence.

Wall drainage device with the use of modern polymeric filter materials, in particular with the use of the shell "Dreniz», reduces construction cost by saving sand.

The shell "Dreniz" consists of a two-layer structure: a sheet of a special profile made of polymeric material (polyethylene, polypropylene, polyvinylAnd lchloride) and non-woven geotextile filter material, fastened together by welding or waterproof glue. Sheath sheets"Dreniz" connect with each other Art.

The technology for the use of this material is indicatedin Instructions VSN 35-95.

Reservoir drainage

To protect against groundwater flooding of basements and underground floors of buildings arranged in difficult hydrogeological conditions, such as: in aquifers of high thickness, with a layered structure of the aquifer, in the presence of pressure groundwater, etc., as well as in case of insufficient the effectiveness of the use of ring or wall drainage, reservoir drainage should be arranged (see Fig. ).

In aquifers of high thickness, it is necessary to first calculate the possible lowering of the groundwater level in the center of the annular drainage contour. In case of insufficient decrease in the level of groundwater, it is necessary to apply layers s and drainage.

With a complex structure of the aquifer with a change in its composition and water permeability (in plan and section), as well as in the presence of flooded closed zones and lenses under the floor of the basement, reservoir drainages are arranged.

In the presence of pressure groundwater, ring or reservoir drainage should be used, depending on local hydrogeological conditions with a calculated justification.

To protect basements and structures in which, according to the operating conditions, the appearance of dampness is not allowed, when laying these premises in the zone of capillary moistening of soils, reservoir drainage should be arranged.

Formation "preventive" drainages for such premises and structures, arranged in clay and loamy soils, are also recommended to be provided in the absence of observed groundwater.

Reservoir drainages are arranged in combination with tubular drainages (ring and wall).

To interface reservoir drainage with external tubular drainage, tubular drainage is laid through the foundations of the building.

For building undergrounds with foundations on pile grillages, formation drainage can be arranged in combination with single-line drainage laid under the building.

Drainage of underground channels

To protect the channels of the heating network and collectors of underground structures from flooding by groundwater, when laying them in aquifers, it is necessary to arrange linear accompanying drainages.

"Preventive" (associated) drainages should be arranged in clay and loamy soils.

Accompanying drainage should be laid on 0,3 - 0,7 m below the base of the canal.

Accompanying drainage should be laid on one side of the channel at a distance 0, 7 - 1, 0m from the outer edge of the channel. Distance 0, 7m is necessary to accommodate manholes.

When arranging through channels, drainage can be laid under the channel along its axis. In this case, special inspection boxes should be arranged on the drainage.l odtsy with hatches embedded in the bottom of the channel.

In the case of laying the foundation of the channel on clay and loamy soils, as well as on sandy soils with a filtration coefficient less than5m / day, under the base of the channel it is necessary to arrange layers s and drainage in the form of a continuous sandy layer.

Formation drainage should be connected to the drainage backfill of the associated tubular drainage.

When arranging channels in clay and loamy soils,in soils of a layered structure, as well as in sandy soils with a filtration coefficient less than 5m/day, on both sides of the channel must be backfilled in vertical or inclined sand prisms with a filtration coefficient of at least e5 m/day.

Sand prisms are designed to receive water flowing from the sides and are arranged similarly to the sand prisms of the head and wall drainages.

Drainage of pits and buried parts of basements

Drainage of pits and underground parts of basements should be decided in each case, depending on local hydrogeological conditions and accepted building designs.

deepening of the lower section of the drainage, when the buried rooms and pits are located at its lower part, counting along the flow of water in the drainage;

general decrease in drainage when laying the drainage and the protected structure in sandy soils;

division of the general drainage into separate parts with independent outlets; arrangement of additional local drainages.

When draining individual pitsin and buried premises, it is necessary to pay special attention to measures against the removal of soil from under the foundations of the building.

When installing circular drainages, the foundations of the building can be laid slightly higher than the drainage. The excess of the foundations of the building above the drainage and the distance of the drainage from the building must be checked taking into account the angle of internal friction of the soil according to the formula:

Where

l min - the smallest distance of the drain axis from the wall of the building in m,

b - broadened And e of the foundation of the building in m,

B is the width of the drainage trench in m,

H - the depth of the drain in m,

h - foundation depth in m,

φ - angle of internal friction of the soil.

When laying drainage below the foundation of buildings in order to exclude soil suffusion, special attention should be paid to the correct selection and installation of drainage sprinkles, to the quality of sealing joints and holes in wells,as well as on measures that exclude the removal of soil when digging drainage trenches.

With a large value of lowering the groundwater horizon under the foundations (existing and designed), the calculation of soil settlement should be carried out.

When arranging drops on the drainage within the zone of influence of the lower drain, the measures listed above should also be provided.

delta s e wells should be arranged with careful sealing of all seams and openings.

Local drainages for individual pits are recommended to be arranged according to the type of reservoir drainage.

Other types of drains

In some cases, the required lowering of the groundwater level can be achieved by a system of general drainage of the territory (head and systematic drainage).

Drainages can be laid together with drains (see fig.).

When backfilling rivers, streams, ravines and ravines, which are natural groundwater drainage, in addition to surface water collectors, it is necessary to arrange drainages for groundwater intake.

The drains must be connected to the aquifer on both sides of the drain collector. With a large influx of groundwater,and also when laying the collector on clays and loams, two drains are laid, placing them on both sides of the collector.

With a small influx of groundwater and the location of the drainage collector in sandy soils, one drain can be laid, placing it on the side of a larger inflow of water. If at the same time sandy soils have a filtration coefficient less than5m / day, under the base of the collector, layers should be arranged s and drainage in the form of a continuous layer or separate prisms.

When wedging out an aquifer on slopes and in slopes, it is necessaryd imo arrange intercepting drainage And.

Intercepting drainages are laid at a depth not less than the freezing depth and are arranged according to the type of head drainage.

When aquifers are not clearly expressed and groundwater wedges out over the entire slope area, speciale slope drains.

When constructing retaining walls, in places where groundwater is wedged out, they arrange a wallth drainage. Zast oh ny drainage is a continuous backfill of filter material laid behind the wall. With a short length, wall drainage can be laid without a pipe. With a considerable length, it is recommended to arrange a tubular drainage with a draining sprinkling.

Capture wells are arranged to catch springs that wedged out on the slope.

Sloping and zastenns Drains and capping wells must have secured water outlets.

To protect existing basements and underfloors of buildings, the type of drainage is chosen on a case-by-case basis, guided by local conditions.

In sandy soils, ring and head drainages are arranged.

In clay and loamy soils at deepabout m laying the foundations, wall drainages are arranged, provided that such a solution is allowed by the design of the foundations and walls of the building.

Plastovy m drainage is arranged in case,when a second floor can be arranged in the basement at higher elevations. In this case, a layer of filtering material (coarse-grained sand with prisms of gravel or crushed stone) is poured between the old and new floors and connected to the external tubular drainage, as in conventional reservoir drainages.

When designing and constructing drainages for existing buildings, measures should be taken to prevent the removal and subsidence of soils.

The opening of the drainage trench in these cases should be carried out in short sections with immediate laying of the drainage and backfilling of the trench.

Drainage route

The routes of the ring, wall and associated drainages are determined by reference to the protected structure.

The routes of the head and systematic drainages are determined in accordance with the hydrogeological conditions and building conditions.

When laying drainage below the sole of the foundations of neighboring structures and networks, the distances between them must be checked taking into account the anglel but the natural slope of the soil from the edge of the base of the foundation of the structure (or network) to the edge of the drainage trench (see).

Longitudinal drainage profile

The depth of the drainage should not be less than the depth of soil freezing.

The depth of the head, ring and systematic drainages is determined by the hydraulic calculation and the deepening of the protected buildings and structures.

The depth of the wall and associated drainages is determined in accordance with the depth of the protected structures.

The greatest drainage slopes should be determined based on the maximum allowable water flow rate in the pipes- 1, 0 m/sec.

Placement of manholes

Lookouts e wells should be installed in places where the route turns and changes in slopes, on drops, as well as between uh small points at large distances.

On straight sections of drainage, the normal distance between manholes is40m. The greatest distance between the manholes of the drainage - 50 m

At the corners of the drainage at the ledges of buildings and at the chambers on the channels, the installation of manholes is not necessary, provided that the distance from the turn to the nearest manhole is not more than20m. In the case when the drainage makes several turns in the area between the manholes, the manholes are installed through one turn.

Release device

The release of water from drains is carried out into drains, reservoirs and a ravine And.

Connection of drains to drains, as a rule, should be carried out above w ate gi drain. In case of connecting a drain below walked gi pipe drain, Location on drain outlet, a non-return valve must be provided. It is not recommended to connect drainage to drains below the water level in the latter during a period of excess 3 times a year.

When released into a reservoir, drainage should be laid above the water level in the reservoir during a flood. With a short-term increase in the horizon of the reservoir, drainage, if necessary, can be laid below the flood horizon, provided that the drainage outlet is equipped with a check valve.

The wellhead section of the drainage outlet into the reservoir should be buried below the water horizon to the thickness of the ice cover with the installation of a drop well.

If it is not possible to drain water from the drainage by gravity, it is necessary to provide a pumping station (installation) for pumping drainage in od, operating in automatic mode.

Combination of drainage with a drain

When designing drainage, consideration should be given toto Lad it together with a drain (see fig.).

With a sufficient depth of the drain, the drainage should be located above the drain in the same vertical plane with the release of drainage water into each manhole of the drain. The clear distance between the drainage and drain pipes must be at least 5cm.

If it is impossible due to the depth of laying to place the drainage above the drain, parallel laying of the drainage in the same trench with the drain should be carried out.

Pipes

Asbestos-cement pipes should be used for drainage.

The exception is drainage laid in groundwater, which is aggressive to concrete and mortars based on Portland cement. In this case, plastic pipes should be used for drainage.

The allowable maximum backfill depths to the top of the pipe drain depend on the design resistance of the bearing soil, pipe material, pipe laying methods (natural or artificial) and trench backfilling, among other factors.

Necessary data on the use of asba st cement x pipes are available in the SK album 2111- 89, and through plastic pipes - in the SK album 2103- 84.

Water intake holes in pipes should be arranged in the form of cuts with a width of 3 - 5mm. The length of the cut should be equal to half the diameter of the pipe. Cuts are arranged on both sides of the pipe in a checkerboard pattern. Distance between holes on one side - 50see. An option is available with drilling water inlet holes (see fig. , ).

When laying pipes, make sure that the cuts are on the side of the pipe; the top and bottom of the pipe must be without cuts.

Asbestos-cement pipes are connected with couplings.

When using PVC s x pipes (P V X) water intake holes are made similarly to asbestos cement s m pipes. Corrugated drainage pipe made of polyethylene (HDPE) is produced with ready-made water inlets (see fig.).

Drainage structures and drainage filters

Drainage sprinkling, in accordance with the composition of the drained soils, is arranged as single-layer or two-layer.

When the drainage is located in the sands, the gravels x, large and medium size (with an average particle diameter 0, 3 - 0, 4mm and larger) arrange single-layer sprinkling of gravel or crushed stone.

When the drainage is located in sands of medium size with an average particle diameter less than 0, 3 - 0, 4mm, as well as in small and n ylevat s x sands, sandy loams and with a layered structure of the aquifer, arrange two-layer sprinkling (see Fig. 20). The inner layer of the backfill is made of crushed stone, and the outer layer of the backfill is made of sand.

Materials for drainage fillings must meet the requirements for materials for hydraulic structures.

For the inner layer of woodn screeding gravel is used, and in the absence of e G o - crushed stone of igneous rocks (granite, syenite, gabbro, liparite, basalt, diabase, etc.) or especially strong varieties of sedimentary rocks (siliceous limestones and well-cemented non-weathered sandstones).

Sands, which are the product of weathering of igneous rocks, are used for the outer layer of gravel.

Drainage fill materials must be clean and contain no more 3- 5% by weight of particles with a diameter less than 0.1 mm.

The selection of the composition of drainage sprinkles is carried out according to special schedules, depending on the type of filter and the composition of the drained soils.

Drainage should be laid in drained trenches. In sandy soils, dewatering with wellpoints is used. When laying drainage on an aquiclude, dewatering with a construction drainage device, freezing or chemical fixation of soils is used.

Drainage pipes of an imperfect type are laid on the lower layers of the draining backfill, which, in turn, are laid directly on the bottom of the trench.

For drainages of a perfect type, the base (the bottom of the trench) is reinforced with crushed stone rammed into the ground, and the pipes are laid on layers of sand with a thickness of 5cm.

In weak soils with insufficient bearing capacity, drainage should be laid on an artificial base.

Drainage fills can have a rectangular or trapezoidal shape in cross section.

Sprinkling of a rectangular shape is arranged with the help of inventory shields.

Sprinkling of a trapezoidal shape is poured without shields with slopes 1:1.

The thickness of one layer of drainage sanding must be at least 15cm.

Pipe filters

Instead of a drainage device from pipes with gravel SCH baby m filter for preventive drainage can be used pipe filters made of porous concrete or other material. The area and conditions for the use of pipe filters is determined by special instructions.

wells

On the tubular drains arrange wells.

Dl I protection from h Clogging wells must be provided with second covers.

delta s e wells on the drainage must have a water part.

sand prisms

When laying drainage in sandy soils from filtration coefficient less than5m / day, as well as in soils of a layered structure, part of the trench above the drainage is covered with sand. The filled sand prism must have a filtration coefficient of at least 5 m/day

Backfilling with sand a trench developed in sandy soils is carried out to a height 0, 6 - 0, 7H, where H is the height from the bottom of the trench to the groundwater level, but not less than 15see above the top of the draining sprinkle. In soils of a layered structure, the trench is covered with sand for 30see above the groundwater level (see fig.).

Filter wells

With a heterogeneous structure of the aquifer, when a horizontal drain passes in the upper less permeable layer, and a more permeable layer is located below, a combined drainage is arranged, consisting of a horizontal drain and vertical self-flowing filter wells (see Fig.).

The penetration of vertical filter wells can be done hydraulically (by immersion with the help of ain a) or drilling method m. In these cases, filter wells are structurally arranged similarly to tubular vertical drainage wells. The mouth (upper end of the tubular well) is located below the general non-lowered groundwater level and is embedded in the bottom of the drainage manhole. The mark of the mouth of the tubular well should be higher than the mark of the horizontal drain tray by 15see At a shallow depth, the installation of filter wells can be done in an open way. For this purpose, wells are opened from the bottom of the horizontal drainage trench, in which pipes are installed vertically (asbestos cement e or plastic), filled with gravel or crushed stone. The space between the vertical pipe and the ground is filled with coarse sand. The lower end of the vertical pipe enters a layer of gravel or crushed stone at the bottom of the wells. but. The upper end of the pipe is mated with the inner layer of the horizontal drain.

Reservoir drainage design

Plastov s th drainage is used to protect the basements of buildings, pits and channels in cases where one tubular drainage does not provide the necessary drainage effect.

Reservoir drainage is arranged in the form of a layer of sand, poured along the bottom of a pit for a building or a trench for a canal.

A layer of sand in the transverse direction is cut with prisms of gravel or crushed stone.

Reservoir drainage must be protected from clogging during constructionbut. When installing floors and bases in a wet way (using monolithic concrete and cement mortars), it is necessary to close the layers s and drainage with insulating material (glassine, etc.). P.).

Gravel (or crushed stone) prisms must have a height of at least 20cm.

Distance between prisms -6÷12 m (depending on hydrogeological conditions). Prisms are being laid, usually , in the middle between the transverse foundations of the building.

With a large influx of water or for especially critical reservoir structuress and drainage can be two-layer over the entire area with a bottom layer of sand and an upper layer of gravel and whether rubble.

With a small width of the protected structure and limited water inflow, in particular under underground channels, reservoir drainage can be arranged from a single layer of sand or crushed stone.

The thickness of formation drainage under buildings should be at least30cm, and under the channels - no less 15 cm.

In some cases, with a large drainage area or special requirements for lowering the capillary saturation zone, the thickness and design of the reservoir drainage are determined by calculation.

Reservoir drainage should go beyond the outer walls of the structure, and, if necessary, fall off along the slope of the pit (trench).

Reservoir drainage must be connected to tubular drainage ring, wall or accompanying.

With a large area And subtitle in many rooms, additional tubular drains should be laid under the floor of the room.

In the undergrounds of buildings erected on piled foundations, reservoir drainage can be arranged in combination with a single-line tubular drainage located under the underground m

Pumping stations (installations) for pumping out drainage water

The depth of the underground premises of residential and public buildings and structures does not always allow drainage water to be directed by gravity into the storm sewer. In this case, it is necessary to install drainage pumping stations. When designing drainage pumping stations, one should be guided by the following:

the installation of separate pumping stations (installations), as a rule, is not economically feasible, because the cost of their construction and operation will be significantly higher than those built into the basement;

pumping units, mainly should be located in buildings, drainage water from which it is not possible to direct to the storm sewer (drainage) by gravity;

With a feasibility study, it is possible to install one pumping station for pumping drainage water from several buildings. Ifh Denmark will belong to different owners, in order to resolve this issue, it is necessary to obtain an appropriate document on equity participation in the construction and operation of a common pumping station, drawn up in the prescribed manner.

When deciding on the placement of pumping stations for pumping drainage water, the priority is to comply with the permissible levels of noise and vibration from pumping units and pipelines in residential apartments and public buildings.

Pumping units should not be located: under residential apartments, children's or group rooms of kindergartens and nurseries, classes of secondary schools, hospital premises, work rooms of administrative buildings, auditoriums of educational institutions and other similar premises.

In projects, it is necessary to make appropriate noise and vibration calculations that determine the choice of technical measures to ensure compliance with the requirements for permissible levels of noise and vibration in residential and public premises of buildings in accordance withMGSN 2.04-97 , manuals to MGSN 2.04-97 "Design of protection against noise and vibration of engineering equipment in residential and public buildings" and "Design of sound insulation of enclosing structures of residential and public buildings."

The flow rates of drainage water sent to the pumping station should be determined specifically for each facility.

As a rule, two pumping units should be provided for the installation, of which one is redundant. When justified, it is allowed to install a large number of pumps. With a limited area of ​​\u200b\u200bthe room to accommodate the pumping station, it is most advisable to use submersible pumps.

The drainage pumping station must have a special room necessary to accommodate the receiving tank, pumping units and other equipment.

Only personnel servicing the installed equipment should have access to the pumping station.

The operation of pumping stations should be provided in automatic mode.

Receiving tank capacity withl should be determined depending on the estimated second flow rate of drainage water, the performance of the selected pump or pumps and the permissible frequency of switching on the pump motor, but not less than 5-minute of its maximum productivity (for domestic pumps). The maximum number of starts per hour for imported pumps must be indicated in the technical documentation of the manufacturer. In the absence of these data, a corresponding request should be made.

To reduce the frequency of switching on the pump, their alternate operation can be provided. In this case, it is necessary to provide3-th reserve pump, which is allowed to be stored in a warehouse. Considering that drainage waters are, as a rule, conditionally clean, it is possible not to provide a special pipeline for sediment agitation in the tank. For polluted waters or when it is necessary to control the flow of wastewater pumped by pumps, the specified pipeline should be provided.

To automate and control the operation of pumping units in the receiving tank of the pumping station, appropriate water levels are assigned.

Worker and Reserve Turn-On Levels pressure pumps must be assigned below the inlet pipe tray. In this case, the activation level of the backup pump is assigned higher than the working one, because it should be switched on not only in case of an emergency stop of the working pump, but also with an increase in the inflow of water and, accordingly, an increase in its level in the tank (i.e., if the performance of the working pump is less than the increased inflow of wastewater).

In the event of a further increase in the water level due to an emergency stop of the pumps or for other reasons, an upper alarm level is assigned, upon reaching which an alarm is given.

Upper AvaR level usually taken at the level of the inlet pipe tray.

Pump shutdown level must be at least 2D in from the bottom of the suction pipe (inlet), and the inlet must be located at least 0.8D inlet from the bottom of the tank but.

These rights l and it is necessary to observe T b for a favorable water supply to the vertical suction pipeline and to avoid air ingress into it.

Lower emergency at level taken in the interval between the shutdown level of the pumps and the inlet of the suction pipelines.

When applied to a blade installations For horizontal or vertical pumps, the geometric suction head of the pumps must be taken into account.

Each pump must havein oh suction pipe.

Suction lines must be airtight. The most preferred are welded joints.

To prevent the formation in the suction pipe duringh stuffy bags, the pipeline is laid with a rise in the direction of the pump (slope not less than 0, 005). For the same reason, when moving from one diameter to another in horizontal sections, only "oblique" transitions with a horizontal upper generatrix (eccentric transition) are used.

Pressure pipelines after installation of check valves and gate valves on them, as a rule, should be combined into one pipeline.

When using submersible pumps, the lower shutdown level must be taken not lower than that specified in the technical documentation of the manufacturer.

Notes :

1.On fig. and examples of wall drainage solutions using drainage systems are presented. Olochka "DRENIZ" and drainage on a pile foundation with backfilling of the sinuses with sand.

2. Methods of hydrogeological and hydraulic calculations of drainage are recommended to be used from the sources given in the appendix.

MGSN 2.07-97 "Foundations, foundations and underground structures"

VSN-35-95 "Instruction on the technology of using polymeric filter membranes to protect the underground parts of buildings and structures from flooding with groundwater", Research Institute M acute

Album No. 84 Institute Mosinzhproekt "Drainages for I drainage of urban areas and protection of underground structures "

Album SK 2111 - 89Institute Mosinzhproekt "Underground non-pressure pipelines from asbestos-cement, ceramic and cast iron pipes"

Album SK 2103 - 84Institute Mosinzhproekt "Underground non-pressure pipelines made of plastic pipes"

Designer's handbook "Complex bases and foundations" M., 1969G.

Abramov S .TO . "Underground drainages in industrial and civil engineering" M., 1967

Degtyarev B. M. etc. "Protection of the foundations of buildings and structures from the impact of underground waters "Stroyizdat, 1985

MGSN 2.04-97 "Permissible levels of noise, vibration and sound insulation requirements in residential and public buildings"

When wet soils (clays, loams, sandy loams, fine and silty sands) freeze, heaving occurs. Heaving is a general or local uplift of the surface of the soil or rail track, the cause of which is the freezing of the soil and an increase in the volume (by 19%) of the water freezing in it.

Freezing usually results in more or less uniform heaving over large areas. In some places, the value of the uniform

swelling is broken: these local distortions are called abysses. The abysses can be in the form of abyssal humps, depressions and drops.

The value of uniform heaving is 30-40 mm, uneven - 200 mm or more.

The abysses are divided into ballast and ground (primary), while in ballast abysses the heaving zone is located within the ballast layer, soil abysses - in the subgrade. The height of ballast abysses is 20-25 mm.

To eliminate ballast abysses, the following measures are carried out: cleaning the ditches, replacing or cleaning the contaminated ballast layer, eliminating or draining the depressions in the main subgrade area.

To eliminate soil abysses, the following is used: replacing heaving soil with draining soil, removing the freezing zone from the soil layer that causes abysses and lowering the groundwater horizon in order to remove it from the freezing zone.

Currently, the last two methods are practically used.

The lowering of the groundwater horizon under the subgrade is carried out using one-sided or two-sided drainages, which are laid under ditches or on slopes.

According to the classification proposed by Prof. G.M. Shakhunyants, drainages are distinguished by the coverage of the object being drained and the nature of work on single, group and drainage networks.

A single drainage is an isolated structure that provides drainage of a specific object.

Group drainage is a series of separate drainages that are not connected to each other into a single system, but created for the same purpose. Group drainage in comparison with a single one reduces the time of draining the object.

A drainage network is a complex of drainages connected to each other into a single system.

According to the nature of the collection and drainage of groundwater, design features and construction methods, drainages are divided into horizontal, vertical, combined and biological

Horizontal drains are open in the form of trays or ditches and closed. Closed drains are the most common.

Vertical drainages are used as drilling or mine culverts and much less often with water pumping.

Combined drains are various combinations of horizontal and vertical drains.

Biological drainage is a system for draining the soil by evaporating moisture from various plants (planting trees, creating a grass cover).

Drainage is called imperfect if its bottom is located above the aquiclude, i.e. there is an inflow of water from the bottom of the drainage and is perfect if its bottom rests on the aquiclude or is cut into it.

The most widespread are tubular drainages of the horizontal type.

The device of drainages gives a great effect in the fight against abysses with soils that give off water well.

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Hydraulic Drainage Calculation - CyberPedia

Drain selection. Above, the water consumption per 1 linear meter was determined. m of designed drainage. Obviously, when calculating the capacity of a drainage pipe-drain, it is necessary to determine the flow rate throughout the entire length of the considered drainage, and in the case of a drainage network, the inflow of water from other underground drainage systems should also be taken into account. Total calculated water flow for the end section of the drainage route:

Transit consumption of water flowing from associated drains;

l - the length of the drainage, as a catchment area;

The coefficient taking into account the possibility of gradual contamination of the pipe is taken equal to 1.5;

q - drainage flow rate.

The cross section of the drainage pipe is usually determined by the method of successive attempts, i.e., it is first set by a certain section and then the compliance of this section with the required throughput is checked. In most cases, these requirements are met by round pipes with an internal diameter of 150 mm. Therefore, the calculation of the section should be started, given this size of the inner diameter.

After assigning the diameter of the pipes, a verification calculation is made according to the formulas known from hydraulics

The desired water flow in the pipe in m3 / s;

Wetted pipe perimeter in m;

Hydraulic radius of the pipe in m;

Pipe cross-sectional area in m2;

The longitudinal slope of the pipe in the design section, determined depending on the accepted value of the difference, and the incoming and outgoing pipes in the manhole and the projected longitudinal slope of the trench bottom:

The distance between the manholes in m. As part of the course project, you can take 25-50 m.

The value of the drop in the manhole is set within 0.1-0.25 m. When designing, the slope of the bottom of the drainage trench is often assumed to be equal to the slope of the bottom of the cuvette, i.e.

Coefficient C (Chezy coefficient) can be approximately determined by the formula of academician N. N. Pavlovsky

where n = 0.012; y = 0.164 at m and y = 0.142 at m. In most cases, m can be considered.

Hydraulic Radius of Round Pipes

Having established all the calculated values, determine Qnp and compare this flow rate with the calculated QD. The calculation ends on the condition .

If it turns out that , then recalculate with a new, larger pipe diameter.

Drainage calculation example

It is required to design and calculate a drainage 50 m long to drain the soil of the main platform of a double-track subgrade in the excavation under the following conditions. The soil is clayey. Estimated freezing depth from the surface of the ballast layer Z10 = 1.7 m. Elevation of the edge of the subgrade Gb = 73. Elevation of the level of non-pressure gravity waters before their decrease Gg.w. = 73. Elevation of the roof of the aquiclude (along the axis of the subgrade) Gw = 65.

The transverse slope of the aquiclude surface was not found during the survey. Soil filtration coefficient k=1.0 cm/h. The average slope of the depression curve Iо = 0.1. Capillary rise of water acc. = 0.7 m. Filtration coefficient of the drainage backfill kd = 0.001 m/s.

The width of the main platform of the subgrade is 12 m. The average thickness of the ballast layer is 0.5 m. The depth of the ditch is 0.6 m. Drainage is designed on a straight section of the track; longitudinal slope of the bottom of the cuvette of the excavation at the site of the drainage device ik = 0.006.

Earthworks for drainage are carried out mechanized using a drainage machine.

We accept for calculation the sub-cuvet bilateral horizontal drainage of the trench type.

The plan and profile of drainage under given conditions are determined by the existing position of the railway line, i.e., the longitudinal axis of the drainage is assumed to be parallel to the railway line, and the longitudinal slope of the bottom of the drainage trench iD, as a rule, repeats the slope of the bottom of the ditch. Thus, in the case under consideration,

Let's determine the depth of the drainage and specify its type in relation to the roof of the aquiclude (see Fig. 3.12).

We accept e = 0.25 m; ho = 0.3 m. For given conditions b=1.25 m. Then

The width of the trench developed by a mechanized method is 2d = 0.52 m. To clarify the type of drainage, we will perform a number of calculations. The mark of the bottom of the drainage at a depth of the cuvette ko = 0.6 m will be

The DG mark is higher than the GW mark. This means that the designed drainage is of an imperfect type.

The thickness of the part of the aquifer above the bottom of the drainage:

The thickness of the aquifer from the bottom of the drainage to the aquiclude:

The depth of the drainage in the lower section is maintained, since the slope of the bottom of the drainage is arranged parallel to the slope of the bottom of the cuvette.

We calculate the flow rate of water flowing to the field wall of the drainage using the formula:

This value according to the table. 3.19 corresponds to . Next, we calculate:

What is more than 3,

Those. in this case T< Тр.

The data obtained give grounds to conclude that in the example under consideration there is a second case of qr calculation, when its value is found by the formula:

To find qr, we define a using the formula:

According to the schedule (see Fig. 3.14) with

Desired water flow qB:

Consumption of water coming from the second half of the bottom of the drainage:

m3/h per 1 line m.

From the interdrainage space through the side wall of the drainage flow comes:

m3/h per 1 line m.

Thus, the total total water consumption per 1 linear meter. m of drainage will be equal to:

m3/h per 1 line m.

Estimated water flow at the lower section of the drainage, taking into account the fact that QТ = 0:

We express the water flow in various dimensions:

QD \u003d 8.75 l / min \u003d 0.15 l / s \u003d 0.00015 m3 / s.

As a drain, we use pipe filters with an internal diameter of mm.

Find the capacity of the pipe. To this end, we define a number of quantities included in the calculation formulas:

Accept ; . Then ;

m/s m/s,

М3/sec, which significantly exceeds QD.

The concept of soil density in road construction differs from that generally accepted in physics. Soil density is the weight per unit volume of the soil skeleton, i.e. weight without taking into account the weight of pore water while maintaining the natural structure (porosity).

cyberpedia.su

3.3.2. Design and calculation of annular vertical drainage

Vertical drainage - groundwater is pumped out from specially laid drilled wells, for a deeper lowering of the groundwater level. The location of the wells is done areal or linear.

When draining an annular vertical drainage site, the following should be known: the site plan, the maximum groundwater level, the elevation of the aquiclude and the soil filtration coefficient.

With the help of the ground flow N m, the depth of the lowering of the groundwater level in the center of the site will be S m, and the ordinate of the depression curve

1. Design procedure

We determine the radius of action of the drainage according to the formula of I.P. Kusakina

2. According to the formula

determine the radius of the circle xo, equal to the area of ​​the rectangle

F = a ∙ b, (3.19)

where a and b are the sides of a rectangle of equal area.

3. According to the formula

determine the preliminary flow rate of the annular drainage Qprv.

4. Using the formula for determining the gripping ability of a well

gzkv = , (3.21)

where gzkv is the gripping ability of the well;

Vq = 65m/day, (3.22)

we compose two inequalities for n-2 wells:

qzvn > Qprv (3.23)

qsq(n –2)< Qпрв. (3.24)

So, for n wells

gzv = 2, (3.25)

where yn = , (3.26)

and for n-2 wells

gzv = 2, (3.27)

where уn-2 = . (3.28)

We set the radius of the ring.

From inequalities (3.23) and (3.24), by selection we determine an even number of wells and distribute them along the contour of the site.

5. According to the site plan, we determine the distance from the center A to each of the wells x1, x2, ..., xn. According to the formula (3.20), we determine the refined water flow rate of the annular drainage Q.

So, for well 6, symmetrically located with wells 1, 4, 9, they draw up a diagram and calculate the distances from well 6 to other wells: x1, x2, ..., xn. In this case, x6 = r. Using formula (3.29), we determine y6:

In a similar way, the groundwater levels of all wells are determined and depression curves are drawn up.

If the required lowering of the groundwater level at the site is not achieved, then the number of wells and their placement are changed.

2. Calculation of the annular vertical drainage

To lower the groundwater level at the location of one of the plant's workshops, a vertical annular drainage was designed, consisting of a number of tubular wells located along the direct contour of the protected structure 40x60 m in size.

The elevation of the site is on average 131.5m. Aquiclude mark (clay of the Jurassic age) 177.5 m. Alluvial coarse-grained sands lie above the clays, covered from the surface with a layer of loam 1–2 m thick. The filtration coefficient of the sands is 20 m/day. Underground waters lie at around 130m, i.e. about 1.5m below the ground.

In order to avoid flooding of underground basements, the groundwater level should be lowered to approximately 125m.

We accept the radius of the wells r = 0.1 m, the value of the decrease in the water level in the center of the site

S = 130 - 125 = 5m.

The size of the aquifer E \u003d 130m - 117.5m \u003d 12.5m.

The calculation procedure is as follows:

2.1. We determine the radius of action of the drainage according to the formula (3.17)

2.2. The depth of water in the soil in the center of action of the wells is obtained

ya \u003d H - S \u003d 12.5 m - 5 m \u003d 7.5 m.

2.3. The radius of a circle that is equal in size to the protected area will be equal to

2.4. The preliminary flow rate of the annular drainage is determined by the formula (3.20)

Qprv = m3/day

2.5. Using formula (9.5), which determines the gripping ability of the well, we calculate the number of wells n, using these two inequalities

qzkan > Qpra and qzkv(n-2)< Qпра или

2 > 3.14 ∙0.1∙ Vg ∙pack n > 3600 and 2∙ 3.14∙ 0.1 ∙Vgуn-2(n-2)< 3600.

At the same time, Vg = 60= 125.8 m/day.

We set the number of wells n = 10. Then according to the formula (3.26)

According to the formula

We check the accepted number of wells n = 10 by two inequalities

2 ∙3.14∙0.1∙ 126.8 ∙5∙10 = 4000 m3/day > 3600 m3/day

2 ∙3.14∙ 0.1 ∙126.8∙ 4.5 ∙8 = 2900 m3/day< 3600 м3/сут.

We distribute these wells along the contour of the workshop.

2.6. We calculate the adjusted water consumption according to the formula (3.20).

To do this, we calculate, according to the plan of the workshop, the distance from its center A to individual wells

x1 = x4 = x6 = x9 = 36m;

x5 = x10 = 30m;

x1 = x3 = x7 = x8 = 22m.

Then Q = m3/day.

2.7. We calculate the levels of groundwater for groups of wells that are in the same conditions.

So, for well 6 (symmetrically located with wells 1, 4 and 9), we draw up a diagram and calculate the distance from well 6 to other wells (Fig. 9c): x1, x2 …..x10.

In this case, x6 = r. Then by formula (3.29) we obtain

9.2.8. Checking the gripping ability of the well

gcq = 2∙3.14 ∙0.1 ∙126.8∙ 6.3 = 540 m3/day > 390 m3/day,

where 390 = = average well flow.

2.9. Let's calculate the groundwater levels for the group of wells 2, 3, 7, 8. Using the same method, we determine

For wells 5 and 10 we get

2.10. We build longitudinal profiles along equal sections of wells and check the necessary lowering of groundwater at the site. If this reduction is not achieved, then change the number of wells and their placement.

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Drainage calculation

Determining the intensity of wastewater inflow

As a rule, the entire volume of incoming wastewater (qi) is formed due to the following factors:

Drainage water volume (qd)

Rainwater volume (qr)

Waste water volume (qs)

The total volume of wastewater (qi) entering the sewer system per unit of time is calculated as follows:

qi = qd + qr + qs (l/s)

Drainage water (qd)

As a rule, in quantitative terms, the amount of drainage water that needs to be pumped out is negligible. If the soil is loose and the drainage system is located below the water table, the nominal volume of drainage water should be determined on the basis of hydrogeological studies. There is a rule of thumb that the following values ​​can be used in the case of soil with normal characteristics (i.e. in the absence of rivers or other waterways in the immediate vicinity, as well as swamps) and if the level of the soil surface is above sea level

Sandy soil:

qd = L x 0.008 [l/s]

Clay soil:

qd = L x 0.003 [l/s]

where L = length of the drainage pipeline.

Rain water (qr)

Rainwater volume is calculated as follows:

qr = i x ϕ x A where i = nominal rain rate (l/s/m2)

ϕ = runoff factor

A = catchment area in m2

The calculation of precipitation intensity should be based on an analysis of the consequences of flooding.

The nominal intensity of rain is not the same in different regions. There are very rough estimates of this parameter:

The most common standards are:

For flat terrain 0.014 l/s/m2

For mountainous terrain 0.023 l/s/m2

The runoff coefficient is a measure of rainfall runoff from a catchment area. The coefficient varies depending on the type of surface and can be determined using the following table:

The catchment area is the area from which water flows into the spillway system.

Waste water (qs)

The calculation of the intensity of sewage inflow from private houses should be based on the number of people living in these houses.

The standard preliminary value for the intensity of wastewater inflow per person per day is considered to be 170 liters.

Important note:

For residential buildings, the sewage flow rate (qs) must be assumed to be at least 1.8 l/s if toilets are connected to the sewer system.

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Calculation of perfect horizontal drainage.

Lecture Search The distance between drains - dryers is determined by the Rothe formula: , where L is the distance between the drainage drains, m; H is the height of the unlowered groundwater level, m; S is the required decrease in the level of groundwater, m; Rice. 2.4. Calculation scheme of perfect systematic drainage. Table 2.2. Soil filtration coefficient Table 2.3. Soil infiltration coefficient 2.2. Calculation of imperfect horizontal drainage. When the occurrence of the aquiclude is more than 5 m, imperfect systematic drainage is laid in the aquifer (at a depth of 3.5 m.) Rice. 2.5. Design scheme for imperfect systematic drainage. The distance between adjacent drains of imperfect drainage is determined by the formula of S.F. Averyanov: where T is the distance from the center of the drain to the aquiclude, m; h2 is the highest point of the depression curve, m; k is the coefficient of soil filtration, m/day, tab. 2.2; p is the coefficient of precipitation infiltration into the soil, m/day, tab. 2.3. The value of B is calculated according to the dependence where r is the radius of the drain, m, (we accept drains with a diameter of 0.2 m) Drainage pipes are laid according to a pre-designed drainage system plan. The minimum slope of the drainage pipe according to the building code is 0.002 in clay soils, and 0.003 in sandy soils. In practice, for normal water flow, the slope of the pipe is 0.005 - 0.01. On the ground, drains-driers are located in such a way that the pipe runs in the ground parallel to the terrain and, accordingly, the depth of the drain-drier does not change throughout its length. Drains are covered with several layers of permeable materials (for example, geotextiles) - first, washed crushed stone or gravel is placed, then sand, and the previously excavated soil is laid on top. The thickness of the backfill ranges on average from 100 to 300 mm (the less permeable the surrounding soil, the thicker the backfill). In order to prevent silting of drains and clogging of perforations, filters made of geotextiles (when reclamation of sandy and sandy loam soil) or coconut fiber (if clay, loam, peat bogs are drained) are used. Calculate the distance between the dryer drains of perfect and imperfect drainage, build the appropriate design schemes. Select the initial data according to the table. 2.4. Table 2.4. Initial data. Option Depth to aquiclude: perfect imperfect 3,75 5,8 3,5 6,5 3,8 7,2 4,0 7,6 4,2 6,8 4,5 5,5 3,7 6,3 3,9 7,4 4,1 9,1 4,3 7,1 Soil type Ground water level 0,4 0,9 0,8 1,1 0,5 0,6 0,4 1,2 0,7 1,3 Dehumidification rate 2,0 2,0 2,0 2,5 2,5 2,5 2,0 2,5 2,5 2,5 Note: soil type 1 - loam, 2 - sandy loam, 3 - medium sand Practical work 3. Scheme of the vertical planning of the village with the provision of drainage and normal traffic and pedestrians. The vertical planning scheme is developed on the basis of the materials of the geodetic underlay and the general plan of the village (city). At this stage of the design of the vertical layout, the main, expedient decisions are determined on the general high-altitude location of all elements of the city, on the organization of surface runoff and measures for the improvement of territories unfavorable for development. The scale of the diagram is taken - 1:2000 - horizontal and 1:200 - vertical. When developing a vertical layout scheme, design (red) marks are determined at the intersection points of the axes of the streets at intersections and in places where the relief changes along the route of the streets and the route of the street itself. Black marks are determined from the topographic plan by interpolation between contour lines. The distance between the marks is taken according to the plan in accordance with the scale. Then, between the intersections, the compliance of the longitudinal slope of the street with the permissible minimum and maximum slopes is checked and the design longitudinal slope is determined by the formula: i - longitudinal slope; h - elevation of marks between intersections, m; L is the distance between intersections, m. Permissible longitudinal slopes are taken -5‰-80‰. On the vertical layout diagram at intersections at the intersection of the axes of the carriageways of the streets or fractures of the slopes, existing and design marks are applied: the arrow shows the direction of the slope of the street, the longitudinal slope is marked above the arrow, and below it is the distance between the intersections of the axes of the streets. The procedure for the final linking of the planning decision with the relief and the clarification of the actual high-altitude organization of the village can be recommended as follows. 1. A general layout plan is applied to the geodetic plan. The streets, along which the design of longitudinal profiles is supposed, are numbered and along their axes the marks of the existing relief are calculated (by interpolation between contour lines) at their intersections and at turns (Fig. 2). 2. Longitudinal profiles are compiled along the axes of the planned main streets, according to the plan in horizontal lines. In the conditions of existing populated areas, where, in accordance with the rules for surveying and compiling geodetic plans, the relief within the street is not shown, the following methods can be used to compile their longitudinal profiles: if the general character of the street does not differ from the relief of the surrounding territory or differs slightly from it, longitudinal profiles are drawn up on the basis of a plan in horizontal lines, and on the territory of the streets the latter are carried out conditionally, in relation to the relief of adjacent territories. If the existing street runs in conditions that differ sharply from the terrain of the neighborhoods adjacent to it (in a cut or along an embankment), it becomes necessary to use leveling profiles. In most cases, such profiles are available in cities along almost all significant streets, usually on a scale from 1:2000 to 1:500. Rice. 3.1. Street numbering and calculation of marks along the axes. The existing leveling profiles, in relation to the scale of the design solution, must be redrawn at a scale of 1:5000. In order not to equip them with unnecessary marks, one should not transfer all the marks from a large scale, but only the main points characterizing the relief of the longitudinal profiles of the streets should be selected. In this case, in addition to the longitudinal profiles, it is desirable to have cross-sections taken every 200-300 m. The design cross-sections will make it possible to judge the height ratio of the street to the adjacent territory and, accordingly, the most advantageous height solution for the longitudinal profile. It should be noted that the leveling longitudinal profiles of streets are also necessary when drawing up a vertical planning scheme in cities with a very weak relief. In this case, the leveling longitudinal profile of the existing street makes it possible to judge its microrelief and, accordingly, facilitates the task of choosing the direction of drainage. 3. The choice of one of the above methods and the identification of either the need to use leveling profiles, or the possibility of doing without them, can be made on the basis of a detailed survey of questionable areas in nature and a thorough study of the geodetic plan. If the reconnaissance survey reveals existing streets with a particularly difficult terrain, the horizontal profile of which cannot be drawn up, and there is no ready-made leveling profile, leveling should be taken care of. Based on the plan in horizontal lines, and, if necessary, on the basis of leveling profiles, approximate directions of slopes and the direction of drainage along the streets are outlined (Fig. 3). 4. Longitudinal street profiles are designed, a design line is drawn, design marks are written out at intersection points, slope changes and in places of significant earthworks (more than 0.50 m), design slopes and distances are written out. The degree of detail of the design solution of the profile is determined by the scale; namely: the design line is applied only in the first approximation, slopes of similar magnitude are generalized, inserts when conjugating slopes of different directions are not projected at all or are outlined in the most general form. Rice. 3.3. Drawing a design solution on a plan. 5. The final design decision (slopes, distances, marks) is transferred from the profiles to the plan, the design marks are written out at the points of the profile break and the intersection of the axes. In the sections of overpasses and bridges, due to the impossibility, according to graphical conditions, to put a high-altitude solution on the plan, in full, the design data is shown only in the places of approaches. 6. In conditions of complex terrain (flat or with steep slopes), in addition to the profiles along the main highways, a solution is given in the plan for secondary streets, which more fully illuminates the drainage conditions and the high-rise solution for the city as a whole. The same elements are written on the plan: slopes, distances, red and black marks in places where slopes change. In the graphic design of the drawing, it is necessary to show the solutions carried out according to the profiles and according to the plan with various conventional signs (Fig. 4). 7. The contours of areas that require significant backfilling or cutting are identified. The volumes of solid earthworks are calculated in the areas of construction of overpasses, bridges and approaches to them on dams, in sections of streets where the average height of the excavation or embankment exceeds 0.5 m, etc. In addition, the amount of land that will be obtained from the foundation pits of capital buildings with cellars. For individual elements, the calculation of earthworks is carried out as follows: in sections of streets where working marks exceed 0.5 m, the calculation is made according to longitudinal profiles; in areas of continuous filling or cutting at working elevations of more than 0.5 m, the calculation is made according to the method of squares. The volume of land from building pits is calculated by multiplying the area occupied by capital development by the average depth of the pit. The area of ​​capital development is taken according to the data of the general planning project (percentage of development). Based on the calculation of volumes for individual elements, a list of earthworks is compiled. Develop a scheme for the vertical planning of the settlement with the provision of drainage, normal traffic and pedestrians. The plan of the settlement is to be adopted in accordance with the option according to adj. one. Practical work 4.



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2.2.3. Hydraulic calculation of drainage pipes

Transit flow rate of water suitable for the upper section of this section:

Qtr = trV (2.11)

For a round pipe: tr=πd2/4, m2 (2.12)

Let's determine the speed of water movement: V=C√RIv, m/s;

χ=πd, m (2.13)

R=tr/χ, m; (2.14)

It is necessary to comply with the condition Qtr1.5 Qadd, where Qadd is the allowable water flow.

2.2.4. Determination of the technical efficiency of drainage and the period of its drainage

The technical efficiency of drainage is determined by the coefficient of water loss m0. The calculation procedure is as follows:

where nГ is the porosity of the excavation soil;

KN/m3; (2.17)

where S is the specific gravity of the soil;

mo=nГ-(1+α)*Wм*γd/γe(2.18)

where  is the value of capillary bound water.

Drainage is effective if μ≥0.2

The soil drainage period t0 is the time during which the found drainage efficiency will be realized, i.e. the groundwater depression curves will take their stationary position. The value of t0 is determined by the formula (in seconds, then converted into a day, dividing the results by 86400 seconds):

where m0 - water loss;

L0 is the length of the depression curve projection along the horizons on the right side, m;

Kf - filtration coefficient;

B - coefficient determined by the formula:

a - half-width of the drainage trench;

1, 2 - some dehumidification functions depending on the type of drainage.

For the field side:

For the interdrain side:

where A is a coefficient determined from the tables depending on h0/H.

Bibliography:

1. Railway track. Ed. T.G. Yakovleva - M.: Transport, 2001

2. Calculations and design of the railway track. Ed. V.V. Vinogradov and A.M. Nikonova - M.: Route, 2003

3. 1520 mm gauge railways, STN Ts-01-95 Ministry of Railways of the Russian Federation, 1995

INITIAL DATA
	Name	Designation	unit	Meaning
					task p.5.2
	Specific gravity of embankment soil				calculation in clause 1.1
					calculation in clause 1.1
					task p.5.4
					task p.5.5
					task p.6.2
		base=0 t.2.embankment			calculation in part 1.1.
					task p.6.4
					task p.6.5
	Specific gravity of water
	GSP Load Width				from directories
			from directories
	Train load width				Sleeper length
	Cross slope of the terrain				task p.5.8
					task p.8.0
	The slope of the depression curve
	Height of capillary rise				task p.5.6
					=(s+v*e)/(1+e)
					\u003d (s-v) / (1 + e)
					=- 0,25*
					=(sbase-in)/(1+eobase)
					=base - 0.25*base
	Specific cohesion of embankment soil in a water-saturated state				Cosn - 0.50 * cosn
					according to the formulas in STN-C 95

	Initial data for the calculation of slope stability 1 sheet
INITIAL DATA
	Name	Designation	unit	Meaning
	Specific gravity of embankment soil particles				task p.5.2
	Specific gravity of embankment soil				calculation in clause 1.1
	Embankment soil porosity coefficient				calculation in clause 1.1
	The angle of internal friction of the embankment soil				task p.5.4
	Specific cohesion of embankment soil				task p.5.5
	Specific Gravity of Base Soil Particles				task p.6.2
	Stresses at the contact of the embankment with the base (along the axis of the embankment)	base=0 t.2.embankment			calculation in part 1.1.
	Base soil porosity coefficient				determined by the compression curve of the base from the stress at the contact of the embankment with the base (along the axis of the embankment)
	Base soil internal friction angle				task p.6.4
	Specific cohesion of the base soil				task p.6.5
	Specific gravity of water
	GSP Load Width				from directories
			from directories
	Train load width				Sleeper length
	Train load intensity
	Cross slope of the terrain				task p.5.8
	Water depth at the calculated level (taken with a probability of 0.33%)				task p.8.0
	The slope of the depression curve
	Height of capillary rise				task p.5.6
	The height of the fictitious column of soil from the VSP
	The height of the fictitious soil column from the train load
	Weight of soil embankment with water in capillaries				=(s+v*e)/(1+e)
	Weight of embankment soil suspended in water				\u003d (s-v) / (1 + e)
	The angle of internal friction of the embankment soil in a water-saturated state				=- 0,25*
	Specific cohesion of embankment soil in a water-saturated state
	Weight of foundation soil suspended in water				=(sbase-in)/(1+eobase)
	The angle of internal friction of the foundation soil in a water-saturated state
	Specific cohesion of embankment soil in a water-saturated state
	Permissible stability factor				according to the formulas in STN-C 95

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How is drainage calculated?

One of the effective ways to protect the local area from excessive waterlogging is the arrangement of deep drainage.

Timely removal of rain and melt water from the site will provide simpler, budgetary surface drainage.

The right choice of drainage system and its installation will effectively protect the foundation of the house and other underground structures from the damaging effects of groundwater.

Important! The efficiency and durability of the drainage system is affected by the correctness of the calculations performed. As a rule, this work is carried out by invited specialists. At the same time, possibilities are being developed for the safe removal of drained water outside the site.

The water collector can be a natural reservoir or a specially equipped drainage well made of plastic or concrete. Underground moisture can be excessively mineralized, and in some regions it can contain undesirable chemical compounds, so it can be used for technical needs after laboratory testing.

When calculating the drainage, the following parameters must be taken into account:

• maximum permanent and seasonal groundwater level,
• granulometric composition of the soil base,
• the availability of the necessary components and the cost of the project as a whole.

Tip: do not try to get such data yourself. The required amount of information can be obtained from the Land Resources Administration.

In addition, the unfavorable hydrogeology of the land plot is evidenced by:

• lack of basements and underground garages in neighboring houses or their periodic flooding,
• excessive soil moisture on which moisture-loving plants, including marsh plants, readily grow.

The complete or partial absence of such signs is not an indication of the absence of a high level of ground moisture. Moreover, undesirable changes in the soil may occur during the construction of houses in neighboring areas. It is not uncommon that after the waterproofing of the pit, the groundwater level in the surrounding areas increased sharply.

Even the most expensive and effective drainage does not eliminate the need for waterproofing the foundation of the house. In the budget option, ring drainage is recommended, with the location of pipes along the perimeter of the foundation and the removal of drained moisture outside the site or into an equipped water collector. The calculation of the ring drainage includes such parameters as:

• foundation depth,
• the possibility of installing pipes with a slope towards the water intake.

Regardless of the material, the pipes are laid below the foundation cushion, not less than 300 mm, the slope is within 1 °, which is 1 cm per linear meter.

Here is a simple calculation of the drainage system:

The collector well is located at a distance of 10 meters from the house, the total length of the trench is 25 m. We take one percent of this value, which is 25 cm. This is the difference between the structure and the top of the collector well. If, due to the complexity of the terrain, this requirement is not feasible, the problem is solved by using a pump that draws and removes water from the system.

The durability of the drainage system can be increased by using efficient filters made on the basis of needle-punched textiles.

This material is characterized by high selectivity, creating an impenetrable barrier to soil microparticles, which contribute to siltation of the system and reduce its productivity.

Today we told you how the approximate calculation and drainage of the site is performed. If you cannot cope with these works on your own or your house is located in an area with difficult soil, you can order drainage work from our professionals!