Lecture on the topic: Engineering organization of populated areas.
Part 11: Organization of drainage surface waters.
Organization of surface water flow
The organization of surface (storm and melt) water flow is directly related to the vertical layout of the territory. Surface runoff is organized using a general territorial drainage system, which is designed in such a way as to collect all surface water runoff from the territory and divert it to places of possible discharge or to sewage treatment plants without allowing flooding of streets, low areas and basements of buildings and structures.
Rice. 19. Schemes for organizing surface runoff depending on the topography of the territory.
The main parameters characterizing rains are intensity, duration and frequency of rains.
When designing rainwater drainage systems, they take into account rainwater giving highest expenses drain. That. For calculations, average rain intensities for periods of various durations are taken.
All calculations are carried out according to the recommendations:
SNiP 23-01-99* Climatology and geophysics.
SNiP 2.04.03-85 Sewerage. External networks and structures
Surface drainage is organized from all urban areas. For this purpose, open and closed drainage system cities that lead surface runoff outside the urban area or to wastewater treatment plants.
Types of rain network (closed, open)
Open network- this is a system of trays and ditches included in the transverse profile of streets, supplemented by other drainage, artificial and natural elements.
Closed- includes supply elements (street gutters), an underground network of pipes (collectors), rain and inspection wells, as well as special-purpose units (outlets, water wells, drop wells and etc.).
A mixed network has elements of an open and closed network.
Closed rain network
Stormwater wells are installed to ensure complete interception of rainwater in places where the design relief is lowered, at exits from blocks, in front of intersections, on the side of water inflow, always outside the pedestrian traffic lane (Fig. 20).
In residential areas, rainwater wells are located at a distance of 150-300m from the watershed line.
Along highways, rainwater wells are placed depending on the longitudinal slopes (Table 4).
Rice. 20 Layout of rainwater wells at intersections
.
Rice. 21. Location of rainwater wells in the highway plan.
1 – collector, 2 – drainage branch, 3 – rainwater well, 4 – inspection well.
The storm (rain) collector located along the highway is duplicated if the width of the roadway of the highway exceeds 21 m or if the width of the highway in the red lines is more than 50 m (Fig. 21, c). In all other cases, use the circuits shown in Fig. 21, a, b.
For ease of use, branch length storm sewer limit 40 m. There can be 2 stormwater wells on it, at the junction of which an inspection well is installed, however, in areas with a large volume of runoff, the number of stormwater wells can be increased (up to 3 at one point). With a branch length of up to 15 m and a wastewater movement speed of at least 1 m/s, connection without a manhole is allowed. The diameter of the branches is taken within the range of 200-300 mm. Recommended slope – 2-5%, but not less than 0.5%
If necessary, rainwater wells are made combined: to receive water from the roadway and to receive water from drainage systems (drains).
Inspection wells are located in places where the direction of the route changes, the diameter and slope of pipes, pipeline connections and intersections with underground networks at the same level, in accordance with the terrain conditions (slopes), the volume of runoff and the nature of the laid storm sewer collectors, on the storm (sewer) network.
On straight sections of the route, the spacing of inspection wells depends on the diameter of the drainage pipes. The larger the diameter, the greater the distance between the wells. With a diameter of 0.2÷0.45 m, the distance between wells should be no more than 50 m, and with a diameter of more than 2 m - a distance of 250 -300 m.
The storm sewer, as an element of the storm sewer, is located in the built-up area of the city, depending on the general layout of the entire storm network.
Laying depth storm drain
depends on the geological conditions of the soil and the depth of freezing. If the soil in the construction area does not freeze, then the minimum depth of the drain is 0.7 m. The depth of installation is determined in accordance with the requirements of SNiP standards.
A conventional drainage network is designed with a longitudinal slope of 50/00, but in flat terrain conditions it is reduced to 40/00.
In flat areas they accept minimum slope collector equal to 40/00. This slope allows for the continuity of movement (constancy) of storm water in the collector and prevents its siltation.
The maximum slope of the collector is taken to be such that the water speed is 7 m/s, and for metal collectors 10 m/s.
At large slopes, collectors may fail due to water hammer.
Possible structures on the drainage network include drop wells, installed in areas with a large drop in relief, to reduce the speed of water in the collector exceeding the highest acceptable standards. If there are significant extreme slopes of the terrain along the collector route, rapid flows, water wells are installed, or cast iron or steel pipes.
For sanitary reasons, it is advisable to arrange outlets of the drainage network outside the boundaries of city buildings in treatment facilities (septic tanks, filtration fields).
Open rain network
consists of street and intra-block. The network includes ditches and trays that remove water from low areas of the territory, overflow trays that remove water from low areas of the territory, and ditches that drain water from large areas of the basin. Sometimes the open network is supplemented by small river beds and canals.
Cross section dimensions individual elements networks are determined by calculation. At small areas drainage, the cross-sectional dimensions of trays and ditches are not calculated, but are taken for design reasons, taking into account standard dimensions. In urban conditions, drainage elements are reinforced along the entire bottom or along the entire perimeter. The steepness of the slopes of ditches and canals (the ratio of the height of the slope to its foundation) is set in the range from 1:0.25 to 1:0.5.
Trays and ditches are designed along the streets. The routes of drainage canals are laid as close as possible to the relief, if possible outside the building boundaries.
The cross-section of ditches and trays is designed to be rectangular, trapezoidal and parabolic, and ditches - rectangular and trapezoidal. The maximum height of ditches and ditches is limited in urban environments. It is made no more than 1.2 m (1.0 m is the maximum depth of the flow, 0.2 m is the smallest excess of the edge of the ditch or ditch above the flow).
The smallest slopes of roadway trays, ditches and drainage ditches are taken depending on the type of coating. These slopes provide the lowest non-silting speed of rainwater movement (at least 0.4 - 0.6 m/s).
In areas of the territory where the terrain slopes are greater than those at which maximum flow velocities occur, design special structures, fast currents, step changes.
Features of designing a rainwater network during reconstruction.
The position of the network in plan and profile is determined by specific design conditions, as well as the height and layout of the territory.
If the existing collector cannot cope with the estimated costs, the drainage network is reconstructed. Design solution in this case, they are chosen taking into account the reduction in the catchment area and the estimated water flow due to the installation of new collectors. Additional pipelines are laid at the same elevations as the existing network or at deeper elevations (if the existing network is not deep enough). Pipes of insufficient cross-section are partially replaced with new ones with a larger cross-section.
In sections of the existing network that are shallow, it is necessary to strengthen the strength of the drainage structure and its individual elements, and, if necessary, provide thermal protection. Continuation of the lecture on the topic: Engineering organization of populated areas.
Part 1: Vertical planning of urban areas.
Part 2:
The foundation of any building may be exposed to groundwater. They, in turn, include special components that can destroy the foundation. Even if the building is waterproofed inside and outside and has supporting walls, they are not able to protect in such a situation. Ground and surface water can significantly damage a building, so you need to take care of drainage on your site.
Only a specialist can correctly assess the situation in a particular area. To do this, you need to study the composition of the soil, do a planned and high-altitude topographic survey, and plan the location of structures. A hydrologist, architect, botanist and surveyor can help with these works. Only with an integrated approach, the drainage of surface and groundwater will solve problems and give a positive result.
Types of systems
The construction of drainage systems can be carried out in two ways: surface and deep. The first method involves planning the territory and carrying out work, including the creation of special slopes from a specific structure, as well as the installation of a drainage network to intercept water. The second method involves draining water using special pipes and consumables.
When arranging modern adjoining areas used closed view drainage. It allows you to save appearance territory, but at the same time it is possible to use the soil above the system for further planting gardening or arranging flower beds.
A simple option for groundwater drainage involves preparing trenches, where the first layer is subsequently filled with sand, then crushed stone, and only after that can drains be installed. A layer of crushed stone will need to be poured on top, then sand. The outside must be covered with turf.
It is necessary to carefully observe the entire sequence of layers, since next to the water there should be a layer of sand, not crushed stone. This coating of crushed stone and sand at the very bottom will be used as a shock absorber, and will also create a slope where unnecessary water will drain. A filter is needed to allow water to pass through and prevent soil particles from entering. If you do not comply correct sequence, then the drainage holes will become unusable.
Protection of the site from the influx of surface water: 1 – water drainage basin; 2 – upland ditch; 3 – construction site.
Stone drainage can be used to drain ground or surface water from a site. In this case, the cavity is filled with stone rather than crushed stone.
Modern drainage systems involve the use of asbestos-cement or plastic pipes. This design is considered more reliable.
Situations often occur when different companies are invited to install a pool on a site and for drainage. In such cases, penetration into the underground environment occurs, which again negatively affects the hydrogeological situation at the site. This may damage the drainage system.
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Installation standards
It will be technically competent to carry out deep drainage of water from the site. Such work can protect not only the foundation, but also basements and other underground structures from flooding by surface or groundwater. According to the standards, it must be at least half a meter below the basement. Drainage pipes differ in their location. They can be single-line, two-line, area or contour.
The drainage system has its own base - a pipe with special holes where water will flow. A cushion of gravel and sand is poured around the perimeter of such a pipe. Pipes are divided into concrete, plastic, asbestos-cement and ceramic. The holes in such pipes must be of such a size that they cannot get in with water. bulk materials. They are located on the sides of the pipes.
The advent of modern pipes has radically changed the entire situation in the installation of drainage systems. Such pipes have a number of advantages compared to the previous generation: flexibility, strength, reliability, durability, and rigidity. Moreover, all these properties are successfully combined at the same time.
High-quality drainage pipes require a perforated structure. This is necessary to ensure that groundwater completely enters the pipe. Also, the pipes must be corrugated. This makes them even stronger and allows them to withstand heavy loads that are inevitable when draining water.
When conducting drainage works For water drainage, you should use only clean gravel and granite crushed stone. Do not use sand-gravel mixture or crushed limestone, as they can clog voids in the soil. That's why drainage system
will have no effect.
The planning of areas for development and other needs must be carried out taking into account the effective removal of precipitation using a drainage system, storm channels and drainage systems. If rain or melt water stagnates, this will contribute to the destruction of the coating and other negative consequences.
Why are surface waters dangerous? Surface water is formed from atmospheric precipitation: snow, rain, hail, etc. This moisture can cause problems on a site (construction site, country house), ranging from elementary stagnation of water from and ending with a violation of the integrity of the foundations of nearby buildings. The troubles do not end there; dampness can also penetrate into buildings and provoke the spread of fungus and increased humidity. There is also a danger for sidewalks and road surfaces: cracking, heavy icing, subsidence of the road surface. Root system Excess rainfall may cause plants to rot, the fertile layer will be washed away, and a violation of the thermal regime will create conditions for the expansion of moss and mold.
In order to avoid all these negative phenomena, an excellent surface water drainage system is needed.
This system comes in two types:
- point;
- linear.
Branches are also divided into open and closed. The second option is more used for draining sediment from entire city blocks. The point method is the simplest; it is most often used when there is a small amount of falling moisture, which is collected in local modules (for example, water flowing from roofs). Linear system more complex and consists of many elements: gutters, trays, ditches, wells, etc. Moisture is quickly collected from a large area and immediately sent to the central drainage collector.
Materials
The materials used are concrete, plastic and earth embankments, ditches and trenches as a temporary solution to the sediment problem. Elements of the surface water drainage system are installed at an angle, which facilitates the rapid collection and discharge of unnecessary moisture. If on site high humidity through groundwater, then the drainage system is designed comprehensively, taking into account atmospheric phenomena and the influence of underground sources. Often, sand, dirt, and debris can get into drainage channels and trays with water, and therefore special traps are installed. 
These devices prevent the system from becoming clogged and stopping performing its direct functions. When drawing up a general project for the drainage of surface water, it is necessary to take into account a number of factors: the amount of precipitation, the territory of the site, the presence groundwater, humidity level, slope.
Surface water- which enter the site as a result of rain or streams that are constantly present on the site.
Ground- which are constantly located underground at some level from the surface of the earth.
The groundwater level varies depending on the time of year. Groundwater is closest to the surface of the earth in autumn and spring.
To drain surface water from the construction site, a system of drainage ditches (ditches) is installed. The ditches are given slopes to ensure water drainage in a given direction.
Groundwater from a construction site can be drained temporarily or permanently.
1. Temporary allotment consists in lowering the groundwater level, as a rule, below the foundation marks (only for the duration of the work).
Water reductions are carried out using special installations - a system of wellpoints (cuts of pipes of small diameter, pointed at the bottom and having holes in the walls), which are installed every 1.5 - 2 m along the entire perimeter of the building. Wellpoints are connected by a common pipeline to which pumps are connected.
2. Permanent tap arranged using drainage.
Drainage– is a system of trenches located on the side of the water supply or along the perimeter of the structure.
The depth of the trenches is taken such that the bottom of the trench is slightly below the required groundwater level.
Groundwater filters through the soil and enters the gravel layer. A large number of voids in such a layer contribute to the further movement of water. Instead of gravel, pipes can be laid at the bottom.
Soil strengthening.
Soils are strengthened in various ways.
1. Cementation – used in sandy soils. Cement mortar is pumped into the ground through wellpoints, which sets with sand to form a waterproof base.
2. Silication – used in loamy and clayey soils. Solutions of calcium chloride and sodium silicate are alternately pumped into the soil, which interact with the soil to form solid foundations.
3. Bituminization – used for wet sandy soils. Molten bitumen is pumped into the ground. It squeezes moisture out of the soil, and when it hardens, it makes the soil more durable.
4. Firing – used for various soils. At the ends of the wellpoints there is a bowl in which fuel is burned. Using a compressor, compressed air is supplied, which pumps hot gas into the ground. Under the influence high temperature the soil is sintered and strengthened.
Questions for the test on “Fundamentals of construction production”
1. History of the development of construction production.
2. Features of construction production in the Republic of Belarus. The role of construction production in the formation of a civil engineer.
3. Types of construction.
4. Construction work and labor organization. General provisions.
5. Construction workers and their training.
6. Technical regulation and legislation in construction production.
7. Composition and content of regulatory and technical documentation.
8. Labor protection and environment in construction industry.
9. Buildings and structures. Types and classification.
10. Main structural elements of buildings.
11. Basic building materials.
12. Quality management of construction work.
13. Organizational and technical preparation for construction.
14. Types of technical documentation.
15. Technological maps and maps of labor processes.
16. General information about soils and land structures.
17. Organization of the construction site. General information about methods of work production.
18. Transport processes.
19. Requirements for design solutions.
20. Protection of structures from ground and atmospheric moisture.
21. Safety precautions during waterproofing work.
Organized drainage of surface water is the most important requirement for the improvement of the site of an industrial enterprise. The accumulation of rain and melt water on the territory of the enterprise impedes the movement of transport, causes flooding of buildings, and this can lead to damage to equipment and destruction building structures. In some cases, if the terrain is unfavorable, flooding of the area can have catastrophic consequences. Incomplete and insufficiently rapid drainage of rainwater, even with light rains, leads to an increase in groundwater levels and premature destruction road surfaces and deterioration of the sanitary condition of the site. Along with rain and melt water, water flowing down the surface of road surfaces during watering and washing must also be quickly drained.
The organization of surface water drainage is decided in the process of vertical site planning industrial enterprise and is one of its main tasks. At the same time, the vertical layout should provide the most favorable conditions for solving issues of transport and technological communication between individual enterprise facilities. The vertical planning schemes selected through a comprehensive solution to the problem largely determine the solution to issues of surface water drainage.
The vertical layout of the site, depending on the extent of coverage of the territory by work to change the natural relief, can be continuous, selective or zonal (mixed). A continuous vertical planning system provides for work to change the terrain throughout the entire site without any breaks. With the selective system, only areas directly occupied by buildings and other structures are planned, and in the rest of the territory the natural topography remains unchanged. With a zonal or mixed system of vertical planning, the territory of an industrial enterprise is divided into zones of continuous and selective planning.
For a selective system, the removal of atmospheric water from the planned areas must be organized and the rest of the territory must be ensured that it is not swamped.
Surface water drainage can be carried out by installing open drains in the form of trays and ditches or an underground rainwater pipeline system. In some cases, it is possible to drain atmospheric water together with domestic and dirty industrial waters. wastewater through common or semi-separate sewer networks.
The open type of drainage requires quite significant areas for placing ditches and necessitates the installation of numerous artificial structures on the roads, complicating transport connections within the enterprise. Open drains do not meet high sanitary and hygienic requirements: stagnant water forms in them and the drains are easily polluted. The only advantage open type drainage is its relatively lower cost. However, the operating costs of maintaining open drains are usually higher than those of containing storm drain pipes.
Application open method drainage is possible with.
some combinations of factors favorable to it, such as:
selective vertical planning system; low building density;
pronounced slope of the earth's surface of at least 0.005, absence of depressions; deep groundwater; rocky soils, well-draining soils; undeveloped scheme railway tracks<50);
and roads; low amount of precipitation (average annual up to 300-400 mm, q^
Sometimes different areas of the territory of industrial enterprises have sharply different building densities, different saturation of communication routes, underground and above-ground communications.
In such cases, a combined zonal drainage system can be used: rainwater drainage is installed in one part of the territory, and a network of open drains is installed in the other.<720- В городах эта система часто предусматривается только на первую очередь строительства.
Recently, due to the increasing requirements for the improvement of sites of industrial enterprises, rain drains have become predominantly widespread. An open drainage system is used for settlements and individual areas of populated areas with a reduced degree of improvement of the territory or with a low building density and low values of the rain intensity indicator
The main (advantages of a closed (underground) surface water drainage system are the following: the presence on the surface of the earth of only stormwater inlets; good conditions for traffic and pedestrians - pollution washed off from the surface is immediately isolated in underground pipelines; independence from groundwater levels; favorable conditions for connection of internal drains; the ability to drain surface water in flat terrain and from low-lying areas; low cost of operation; no difficulties in operation “In the spring; no need for annual repairs; the ability to use for the disposal of clean industrial wastewater that does not require treatment.