The slope of the drainage pipe: calculations, standards + features of the installation of drainage on the slope
Flawlessly designed and well-calculated drainage will collect and drain groundwater from the site. It will protect the foundation from premature destruction, ensure normal growth of cultivated plants. In order to ensure the spontaneous flow of the collected water system, it is necessary to ensure the slope of the drainage pipe. And for his device need accurate information, right?
You will learn all about the angle at which the drainage pipes fit and how to properly organize the drainage system from the article we have proposed. Following the technical recommendations presented by us, you will be able to design and accurately calculate the drainage network. The basis for these data are building codes.
To help the independent masters, the technology of the water drainage system is described in detail, the specifics of the calculation and installation of its components are thoroughly analyzed. For visual perception of information attached photos and videos.
Design features of drainage
There are three types of drainage systems, each of which has its own design features:
The working elements of horizontal drainage can be:
- tubular drains;
- gallery drains;
- trays and trenches.
The system of drainage pipes in combination with filtering dusting (multilayer) - this is the tubular drain.
In this case, multilayer filtering sprinkling is done in order to prevent leachable soils from entering the system. By standards, the drainage circuit is always equipped with manholes.
Unlike tubular drains, gallery drains are made from pipes of a larger cross section. On the walls of the pipes there are holes for collecting wastewater. The process of device gallery drains also provides for the filling with additional filtering geotextile.
The drainage system with trays and trenches is usually done in such conditions when the groundwater level is allowed up to 1.3-1.5 m. On stable soils, trenches are made with slopes; on unstable soils, trenches are reinforced with reinforced concrete structures.
The vertical drainage system consists of a set of wells (wells) connected by a collector. Through the collector line is the removal of waste through a pumping station. Also drainage on vertical drainage can be carried out by dumping into the lower layers of the soil.
The combined drainage system combines horizontal and vertical schemes. It is characterized by specialists as a complex drainage scheme and is usually arranged in areas where highly efficient drainage of soils is required.
Surface and deep circuits
Based on the calculated parameters of the depth of the drains, distinguish surface and deep drainage schemes.The purpose of the surface scheme is to collect and dispose of products of atmospheric precipitation, as well as nearby groundwater. The purpose of the depth scheme is to reduce the level of groundwater, their collection and removal beyond the boundaries of the site where the construction site is located.
Drainage intake pattern supports point or line design. In the first case drainage from local sources (drains, pits of sidewalks, collections of entrance groups) is carried out. The linear scheme provides water drainage throughout the facility. As a rule, a combined solution with the introduction of both schemes is used at residential construction sites.
Depth drainage is obligatory in almost all cases of private housing construction and improvement of household plots. This is an effective protection of those elements of building structures that are located below the zero level (foundation, basement rooms, the root system of plants).
It is permissible to exclude the construction of deep drainage at elevations where the groundwater level does not exceed 1.5 m, where there is effective drainage of the soil.
Designing a deep drainage scheme requires high precision calculations. Even a minor error in calculations can cause a low system efficiency. The practice of installing such schemes often indicates a common mistake - an inaccurate calculation of the depth of the laying of drains. The result is an uneven drainage of water from the territory of the object or, even worse, the flooding of fertile land, basements.
Drainage: calculations and standards
The estimated values that will be required for the construction of the drainage system, as a rule, are:
- diameter of pipelines;
- piping level;
- pipe slope values;
- geotextile density filter.
And more about each item.
Estimated piping diameter
The required diameter of pipelines is calculated with emphasis on the design parameters of the sewage intensity. For private housing construction, pipes with a diameter of 100 mm are usually optimal. Their standard capacity is about 7 l / s, which is fully consistent with design standards in most cases. At the same time, an increase in the diameter of the drain makes it possible to cover a large working area and enhance the efficiency of the system.
The level of laying of drainage pipelines, according to existing standards, is determined taking into account two criteria:
- The degree of soil freezing.
- The depth of the foundation.
The degree of soil freezing is directly related to the climatic properties of the area. Therefore, for each individual territory, this parameter may differ. But in any case, the calculation of the depth of the laying of drainage pipes is conducted from the end point of the soil freezing with the addition of at least 300-500 mm to the additional depth.
By the same algorithm, the base drainage is calculated, but from the end point of the bedding of the foundation.
Drainage pipe slope
Under what slope to mount the pipes of the drainage system, clearly indicate the standards of SNiP. According to these standards, the minimum slope of the drain should be taken taking into account the allowable minimum flow rate of wastewater.
In addition, it is further stipulated that for pipes with a diameter of 150 mm the minimum allowable slope must be at least 8 mm per meter of length, and for pipes with a diameter of 200 mm at least 7 mm per meter of length. On certain sections of the network, it is allowed to underestimate these parameters to 7 mm and 5 mm, respectively.
The permissible maximum slope of drainage pipes per meter length is 150 mm. More than this value, we allow a slope only on the outlets from plumbing devices with a length of up to 1.5 m. On off-drain sections, where pipes with a diameter of 40-50 mm are used, we assume a slope of up to 30 mm per meter of length. And for pipes with a diameter of 85-100 mm and under the same conditions, the level of the slope is allowed to be no more than 20 mm per meter of length.
If trays are used as retraction elements, the slope level is taken with an eye on such a drain rate at which the effect of liquid self-cleaning is provided. Permissible filling of trays is not higher than 80% with a tray width not less than 20 mm.
The width of the trays is calculated based on the results of hydraulic calculations and depends on the design features of the elements. However, if the tray height is greater than 50 mm, the width cannot be less than 70 mm.
The required density of geotextiles
When the project of the drainage system provides for the use of perforated corrugated pipes as a drain, it is recommended to use a geotextile filter casing (geotextile) along with sprinkling of such pipes.
Geotextile canvas performs the function of the filter element, prevents clogging of the highway with small particles of soil. To obtain the maximum filtering effect, a geotextile filter density calculation is required.The optimal calculated value for household drainage systems is considered to be a density of 100-150 g / m2.
Features of the installation of drainage on the slope
Drainage systems provide drainage due to the slope of drains. It would seem that, provided the site is located on a slope, water should be discharged from the site in a natural way, and there is simply no need for a drainage system. However, the situation in such cases is quite different, and the drainage of the section on the slope becomes as relevant as for those with a slope horizon of less than 8%.
Of course, drainage on the slopes is accompanied by its own characteristics. Often the soil on steep slopes has a heterogeneous structure. Different levels of groundwater can be observed at different horizons. Therefore, it is often necessary to use combined drainage types in order to provide the necessary degree of drainage of the entire territory of the site.
Meanwhile, in the construction of drainage systems on slopes with a level of more than 8%, standards allow for the absence of drainage manholes.
Scheme and order of the device
The organization of drainage at a site with a slope level of more than 8% begins with geological surveys. According to the results of surveys determine the aquifers, the levels of occurrence of groundwater. On the basis of the information received, a project is being developed for the drainage of a site on a slope;
In the end, the problem of eliminating the possibility of soil erosion by a chaotic natural drainage system due to the steepness of the slope should be solved. In a simple version, this is done approximately as follows:
- At the upper mark of the site, the first horizontal surface drain is created.
- A second horizontal surface drain is created at the lower elevation of the site.
- Both drains are connected by perpendicular trenches.
- From the horizontal drain of the lower level, they are diverting to a drainage well.
If the landscape of the site has a stepped complex shape and the project of the object provides for the construction of retaining walls, stairs, transitional platforms, for each of the project elements it is necessary to construct point drainage systems, passing into the system of linear drainage systems.
The large areas located on the slopes are, as a rule, not equipped with single surface drains, but with full-fledged “herringbone” type water collection and drainage systems. Branched drainage is arranged on the upper horizon and is combined with the collector drainage circuit surrounding the construction object. From the contour, the wastewater is transferred to an off-site collection or to storm sewers.
Such a circuit is called a circular drainage. Thanks to the construction of a protective circuit located along the perimeter of the object, it is possible to take control of the groundwater level. In turn, the "Christmas tree" provides for the collection of water from the surface of the site and its effective drainage.
Installation of ring drains is carried out at some distance from the construction object. This factor allows you to build a ring drainage system directly at the stage of operation of household facilities.
It should be noted that the effectiveness of lowering the level of groundwater within the boundaries of the inner part of the circuit directly depends on the following parameters:
- pipe penetration level;
- the depth of the galleries;
- well penetration level (if any).
The effectiveness of protection is also influenced by the size of the contour.
Conclusions and useful video on the topic
A few practical tips on laying drainage pipes will help you to cope with the drainage system on a country site.
Protecting land plots (territories) from over-saturation with moisture is an urgent task that has to be addressed in almost every case of construction. Existing development of drainage systems can solve such problems. The main point - to calculate and select the option of the device drains, which would be ideally suited in each case.