WO2023173569A1

WO2023173569A1 - Method for treating underground water disaster of weak-permeability soil layer slope

Info

Publication number: WO2023173569A1
Application number: PCT/CN2022/092440
Authority: WO
Inventors: 曹作忠; 张默; 张显; 代永新; 倪强; 杨强胜; 刘丰恺; 曾学敏
Original assignee: 中钢集团马鞍山矿山研究总院股份有限公司; 华唯金属矿产资源高效循环利用国家工程研究中心有限公司
Priority date: 2022-03-17
Filing date: 2022-05-12
Publication date: 2023-09-21
Also published as: ZA202302413B; CN114575359A; CN114575359B

Abstract

Disclosed in the present invention is a method for treating an underground water disaster of a weak-permeability soil layer slope. A three-dimensional seepage drainage system, a vacuum drainage aiding system, a self-flowing direct drainage system and a siphon drainage system are provided. The three-dimensional seepage drainage system comprises a horizontal seepage drainage shock tube (8), a vertical seepage drainage shock tube (17) and a water collection well (5). The vacuum drainage aiding system is composed of a vacuum pump (11) and a vacuum suction pipe (10). The direct drainage system comprises a water guide hole and a direct drainage pipe (21). The siphon drainage system comprises a deep well pump (12), a siphon pipe (15) and a siphon water supplementing pipe (13), wherein the deep well pump (12) is mounted at the bottom of the water collection well (5), a water input end of the siphon pipe (15) extends to a lower portion of the water collection well (5) along an inner wall of the water collection well (5), and the siphon pipe or the direct drainage pipe can automatically drain the water in the water collection well. By means of the present invention, smooth and centralized drainage of underground water of the weak-permeability soil layer slope can be effectively achieved, thereby preventing the saturation and erosion damage of the slope surface soil layer, and improving the lasting stability of the slope.

Description

A method for controlling groundwater disasters in weakly permeable soil slopes

Technical field

The invention belongs to the technical field of slope water damage control, and specifically relates to a method for controlling groundwater disasters on weakly permeable soil slopes with a permeability coefficient of less than 10 ^-4 . It is suitable for groundwater on all types of soil slopes, especially groundwater on weakly permeable soil slopes. Management of slope instability.

Background technique

Soil slopes, especially soil slopes deposited in rivers and marine facies, have complex soil geology, varying soil permeability, and poor stability. Groundwater or rainfall often forms underground stagnant water in the soil layer or causes the slope soil layer to be saturated, seriously affecting the stability of the slope. Due to the low permeability coefficient of this type of stratum, it brings great difficulties to slope maintenance work. difficulty. For soil slopes with low permeability coefficients, effective drainage (seepage) projects need to be adopted to control the groundwater in the slope soil.

With the continuous development of production and construction and mineral resources, the scale of foundation pit projects and slope projects along coasts, rivers, lakes and moraine soil areas continues to expand. The problem of geological disasters caused by weakly permeable soil layers has become increasingly prominent. Many The stability of soil slopes is affected to varying degrees. According to statistics, more than 90% of slope and foundation pit instability in my country is related to groundwater or rainfall.

Studies have shown that groundwater in slopes can significantly reduce the shear strength of soil and is one of the main factors causing soil slope damage. This phenomenon is more prominent in slopes with weakly permeable soil layers with hydrophilic base, while groundwater discharged from slopes , reducing soil moisture content is an important means to increase slope stability. During the excavation process of open-pit mining, road and building slopes, and building (structure) foundation pits, as the slope increases or the foundation pit deepens, if the groundwater in the soil layer is not drained in time, the slope will The high moisture content of the soil will reduce the stability of the slope or pit wall and endanger the safety of the underlying operations. Therefore, it is urgent to lower the groundwater level of the soil slope and conduct organized discharge to ensure the safety of the slope or foundation pit.

At present, there are two main types of groundwater treatment methods: one is used for foundation treatment or foundation pit soil drainage or drainage, such as open trench plus collection well dewatering, jet well point dewatering, electroosmotic well point dewatering, and tube well point dewatering. Precipitation, deep well point precipitation, interception curtain wall interception, etc. The other type is used for slope precipitation, such as slope seepage trenches, seepage stacks, support blind trenches, inclined dry holes, water collection wells, siphon drainage, Grouting curtains, underground diaphragm walls, drain tunnels, etc.

Dewatering well technology is widely used in drainage projects. For example, in the 1960s, in order to solve the problem of water seepage in underground workshop structures, dewatering wells were set up next to the workshops to collect water and then be pumped out through vacuum pumps; in 1976, the Northwest Research Institute of the Academy of Railway Sciences Combined pumping and drainage of water from manholes was used to control landslides on road cutting slopes along the Longhai coast; in 1979, siphons were used to collect water from manholes in the region to central wells for hydraulic irrigation; in 1985, the Tianjin Harbor Engineering Research Institute conducted research on soft soil The technology of draining groundwater into a sand cushion, directing the water from the sand cushion into a collection well through a blind ditch, and then draining the water out by a water pump was adopted; in 1994, radial seepage well technology appeared. The above drainage methods using dewatering wells essentially use the artesian flow of water collection wells to collect water and discharge it through vacuum pumps. It is currently the most widely used form of dewatering wells. It is mainly used in soil layers with strong water permeability for small projects, directly The application of dewatering wells in large-scale slope drainage projects is rare, and the treatment method for slope drainage in weakly permeable soil layers has not been reported. The main reason is that long-term power supply and pumping of slopes not only consumes a lot of energy, but also requires complex processes. , and management is difficult.

At present, research on slope groundwater mainly focuses on numerical simulation of slope water inflow and optimization of drainage engineering layout. In the article "Numerical Simulation of Water Inflow at the South Slope of the Ekou Iron Mine Open Pit" published in the Chinese magazine "Modern Mining" in December 2016, the two-dimensional finite element analysis software GeoStudio and AutoCAD-3Dmine joint modeling technology were used to construct a numerical simulation The simulated seepage calculation model was used to conduct a numerical simulation analysis of the water inflow on the south slope of the Ekou Iron Mine open pit pit, providing a basis for the design of the mine's slope water inrush control project. Liu Zhimin proposed an objective function method to optimize the layout of dewatering wells in foundation pits; Teng Kai proposed a foundation pit interference depth reduction method based on the theory of interference well groups for the problem of drainage efficiency of well points in rectangular foundation pits; Sun Ronlin relied on numerical simulation technology , using a three-dimensional seepage model to calculate the water inflow from dewatering wells under complex hydrogeological conditions, and obtain the optimal layout of dewatering wells; Wang Zhicheng collected hydrogeological data in a certain area, analyzed the water level drawdown required for slope stability, and developed The program obtains the reasonable slope angle and depth of the slope drainage hole, and so on. In the article "Analysis and Control of Water Inflow on the Southeast Side Slope of Jinduicheng Stope" published in July 2015 in the Chinese magazine "Modern Mining", a concrete cutoff wall was used to cut off the hydraulic connection between the Dongchuan River and the stope. , reducing the amount of water inflow on the slope, but this treatment measure is not suitable for diversion and drainage of groundwater on the slope.

Chinese patent ZL201820898669.0 discloses a series-parallel underground three-dimensional drainage system suitable for edge landslide projects. The patent includes a water collection system and a drainage system. The water collection system includes water collection wells, inter-well guide pipes, inclined drainage pipes and water outlets. The bottoms of adjacent water collection wells are connected by inter-well guide pipes, and the inter-well guide pipes are connected to the water outlets; inclined drainage pipes One end of the pipe is connected to the water collection well, and the other end is located inside the slope. The inclined drainage pipe is set upward along the wall of the water collection well; the drainage system includes a drainage tunnel, a seepage pipe and a drainage hole. The inventive device is buried underground and is mainly used to prevent and eliminate surface water seepage and bedrock fissure water from seeping into the landslide area, and reduce the moisture content of the edge (slide) slope area. However, the series-parallel underground three-dimensional drainage system has a complicated structure, a large amount of work, and a high cost. It is mainly suitable for landslide control and is not suitable for groundwater drainage in weakly permeable soil layers before slope failure.

At present, there are no publicly available groundwater collection and drainage management technologies for groundwater disaster management on weakly permeable soil slopes.

Contents of the invention

The purpose of the present invention is mainly to provide a compact structure, economical and durable, stable and firm, and implementable drainage system that is compact in structure, economical, durable, stable, and practical in order to solve the problems existing in the existing technology such as the drainage system has a complex structure, a large amount of work, a high cost, or is not suitable for slope drainage of weakly permeable soil layers. It is convenient and can effectively realize the centralized discharge of groundwater in weakly permeable soil slopes, prevent slope saturation and slope erosion, and increase the long-term stability of the slope. This method can realize the control of groundwater disaster in weakly permeable soil slopes. The permeable soil layer naturally drains and collects seepage.

In order to achieve the above object of the present invention, the present invention is a method for controlling groundwater disasters in weakly permeable soil slopes with the purpose of accelerating soil drainage and improving the overall stability of soil slopes, and adopts the following technical solutions:

The present invention provides a method for controlling groundwater disasters in weakly permeable soil slopes. The weakly permeable soil slopes are provided with an upper level platform, a water collection well platform, and a water interception and drainage platform from top to bottom. The water collection wells are vertically arranged on The water collection well platform is characterized by a combined seepage drainage system and the following technical solutions:

1) Based on hydrological and geological data, determine the scope of groundwater treatment on weakly permeable soil slopes; determine the number and layout locations of combined drainage systems based on the location of weakly permeable soil slopes and the size of the treatment area; based on the permeability of the soil layer, Determine the amount of water inflow, determine the number of vertical drainage pipes, horizontal drainage pipes, and straight drainage pipes; determine the depth and diameter of the water collection well based on geological data and construction technology;

2) The combined seepage drainage system is composed of a three-dimensional seepage drainage system, a vacuum assisted drainage system, and a siphon/direct drainage system:

The three-dimensional seepage drainage system includes horizontal seepage drainage flower tubes, vertical seepage drainage flower tubes, and water collection wells. The vertical seepage drainage flower tubes are located in the upper platform and pass through weakly permeable layers of different permeabilities from top to bottom. , permeable layer, the vertical drainage flower tube serves as the vertical drainage channel of the soil layer; when the vertical drainage flower tube also serves as a groundwater level observation hole, add a vertical drainage pipe sealing cover to the mouth of the vertical drainage flower tube Sealing; the water collection well is arranged vertically in the water collection well platform; the horizontal drainage flower pipe extends horizontally into the upstream stratum with relatively good permeability below the upper level platform at a slope of 1 to 2%. At a certain depth, the upstream of the horizontal drainage flower tube and the lower end of the vertical drainage flower tube are in the same stratum. The lower end of the horizontal drainage flower tube is connected with the lower part of the water collection well, so that the vertical seepage water can be discharged into the water collection well through the horizontal drainage flower tube. ; The water collection well is composed of a well shaft and a water collection well sealing cover. The well shaft and water collection well sealing cover are reinforced concrete structures. The water collection well is a connecting device of the entire system, responsible for the functions of collecting water and forming a vacuum space. When working, the entire The wellbore is sealed.

The vacuum drainage system is composed of a vacuum pump and a vacuum pipe. The vacuum pump is fixed on the sealing cover of the water collection well. The upper end of the vacuum pipe is connected to the vacuum pump. The vacuum pipe passes through the sealing cover of the water collection well. The lower end of the air pipe extends into the lower part of the water collection well near the outlet of the horizontal drainage flower tube. The main function of the vacuum drainage system is to maintain the vacuum degree of the set water column in the water collection well. The vacuum exhaust pipe is sealed and connected with the sealing cover of the water collection well.

When the horizontal distance between the bottom of the water collection well and the slope of the same elevation is less than 75m, a self-flow direct drainage system is adopted. The direct drainage system includes a water guide hole and a straight drainage pipe. The water guide hole is located in the water collection well. The bottom is close to the side of the slope. The straight drainage pipe is located in the slope body at the lower part of the water collection well platform. The water inlet of the straight drainage pipe is connected with the water guide hole. The water outlet section of the straight drainage pipe is from the slope downward to the drainage platform. Then it extends outward to the lead-out position, and the water in the water collection well overcomes the vacuum resistance and is automatically discharged from the water conduction holes and straight drainage pipes.

When the horizontal distance between the bottom of the water collection well and the slope of the same elevation is >85m, a siphon drainage system is used; the siphon drainage system includes a deep well pump, a siphon pipe, and a siphon water supply pipe. The deep well pump is installed at the bottom of the water collection well, and the water inlet of the siphon pipe The end extends along the inner wall of the water collection well into the lower part of the water collection well. A control valve is provided on the siphon pipe located outside the sealing cover of the water collection well. The water outlet section of the siphon pipe passes through the water collection well platform and down the slope to the interception and drainage platform and then extends outward to the outlet position. , the deep well pump is connected to the water replenishment port of the siphon water replenishment pipe. The siphon water replenishment pipe passes through the water collection well sealing cover and is connected to the siphon pipe near the water collection well sealing cover through a control valve; the distance between the water inlet end of the siphon pipe and the bottom of the water collection well is generally 0.4~ 0.7m, preferably 0.5m. When the water in the siphon pipe is insufficient, water is replenished from the water collection well through the deep well pump. When the siphon pipe is operating normally, the deep well pump stops working.

When the horizontal distance between the bottom of the water collection well and the slope surface of the same elevation is between 75 and 85m, one of the self-flow direct drainage system and the siphon drainage system is determined to be used based on the difficulty of construction and construction cost.

The work and conversion of the entire combined drainage system are automatically opened and closed under the automatic control system composed of sensors and microcontrollers.

In order to facilitate drainage, a one-way valve or an electric control valve is installed on the straight drainage pipe; the lower end of the vertical drainage flower pipe is located near the horizontal drainage flower pipe, and the distance between the two is no more than 1m; The vertical distance between the entrance of the straight drainage pipe and the outlet of the horizontal drainage flower pipe shall not be less than 8m.

This valve is a method for controlling groundwater disasters in weakly permeable soil slopes using the following steps for construction:

1) Construct a water collection well in the water collection well platform, and leave a mark at the position of the highly permeable soil layer with a permeability coefficient greater than 10 ^-3 . At the same time, construct a vertical drainage flower in the first level platform upstream of the water collection well. The pipes are made to pass through the weakly permeable layer and the aquifer layer with different permeability respectively, and the upper end of the vertical drainage flower tube is blocked. The blocking section of the vertical drainage flower tube is not less than 2m.

3) After the construction of the water collection well reaches the design depth, construct a straight drainage pipe in the direction of the water collection well close to the slope. The slope ratio of the straight drainage pipe is 2 to 5%. After the construction of each straight drainage pipe is completed, the straight drainage pipe Install a one-way valve or electric control valve on the pipe, and seal the intersection between the straight drainage pipe and the well wall of the water collection well;

Or install a deep well pump, siphon and control valve and keep the drainage system in working order.

4) According to the marks left during the construction of the water collection well, construct the horizontal drainage flower pipe from bottom to top, and make the horizontal drainage flower pipe pass near the soil layer where the vertical drainage flower pipe is located; the construction of each horizontal drainage flower pipe After completion, seal the intersection between the horizontal drainage flower pipe and the well wall of the water collection well.

5) After the installation of the horizontal drainage flower pipe is completed, install the vacuum exhaust pipe, and finally install the vacuum exhaust pump, and seal the water collection well sealing cover so that the entire system is in a normal pressure drainage state.

6) After the above project is completed, the vertical drainage flower pipes will drain the groundwater in the weakly permeable layer and the stagnant water in the aquitard layer in the upper soil layer to the horizontal drainage flower pipes or the soil layer where the horizontal drainage flower pipes are located, and then from the horizontal drainage flower pipes The seepage drainage flower pipe is discharged to the water collection well, and then discharged out of the slope through a straight drainage pipe or siphon pipe, thereby realizing normal pressure drainage of weakly permeable soil layers.

7) After normal pressure seepage drainage works normally, close the control valve on the siphon pipe and turn on the vacuum pump installed on the sealing cover of the water collection well at the upper end. When the air pressure in the water collection well is lower than the air pressure outside the well, weak penetration will be achieved. Negative pressure drainage of soil layers.

8) When the air pressure in the water collection well is close to vacuum, turn on the deep well pump and open the control valve on the siphon. When the siphon drains normally, close the vacuum pump and deep well pump to achieve negative pressure drainage and gravity drainage of the entire system.

Furthermore, the total height H1 of the water collection well should be less than the vertical height H2 from the wellhead of the water collection well to the direct drainage pipe/siphon outlet, and the difference in vertical height between the two should be greater than 15m.

Horizontal drainage flower pipes, vertical drainage flower pipes, siphon water supply pipes, and straight drainage pipes are made of steel pipes or engineering plastic pipes. The size and strength are determined by hydraulic calculations such as the stratum strength, drainage head, etc., and are based on the current construction equipment and technology. , the diameter of the vertical drainage pipe should not be greater than 75mm, and the diameter of the straight drainage pipe should not be greater than 90mm; the length of the siphon pipe is determined by the depth of the water collection well and the outlet position, and the height difference between the siphon pipe inlet and outlet is required to achieve gravity flow The water head difference is determined, but shall not be less than 15m; the vertical seepage drainage flower tube shall be made of steel pipe, engineering plastic pipe or seepage blind ditch material with an opening rate of not less than 10%, and the upper end of the vertical seepage drainage flower tube shall extend out On the ground surface, seal the vertical seepage pipe sealing section with sealant or expansion cement slurry within a depth of 2m from the ground surface. The length of the horizontal drainage flower tube, the vertical drainage flower tube and the depth of the water collection well are determined by the construction technology, soil properties, precipitation range and the effect to be achieved based on the seepage field calculated by the finite element method.

Further, the horizontal drainage flower pipe adopts a steel pipe or an engineering plastic pipe with an opening rate of not less than 10% in the upper half of the pipe. The horizontal drainage flower pipe is located around the wall section of the water collection well and is surrounded by structural glue or expanded cement. slurry for sealing.

Further, the part of the siphon pipe located inside the water collection well and the part passing through the water collection well sealing cover are made of steel pipes or engineering plastic pipes, and are sealingly connected with the water collection well sealing cover.

Further, the upper end of the vertical drainage flower tube is sealed with cement slurry or chemical slurry; the sealing cover of the water collection well is sealed with asphalt or sealing glue; the gap between the vacuum exhaust pipe and the water collection well sealing cover is The space is sealed with asphalt or sealant.

The invention is a method for controlling groundwater disasters in weakly permeable soil slopes. Its principle is to first establish a three-dimensional drainage system and a vacuum assisted drainage system to effectively collect the groundwater in the weakly permeable slope soil layer, and then use a siphon drainage system or gravity drainage system. The direct drainage system guides and discharges the collected groundwater. During the drainage process, the head difference between the inlet and outlet of the drainage pipe is used to maintain a certain degree of vacuum in the sealed water collection well, thereby smoothly draining the groundwater from the weakly permeable slope soil layer. Outside the slope, it effectively solves the problem of instability of weakly permeable soil slopes due to high groundwater levels.

A groundwater disaster control method for weakly permeable soil slopes of the present invention has the following positive effects after adopting the above technical solution:

(1) The three-dimensional drainage system can automatically remove the water in the soil layer with good permeability under normal pressure; the vacuum drainage system can automatically remove the water in the soil layer with poor permeability under negative pressure, thus solving the problem. The problem of difficult drainage in weakly permeable soil;

(2) Siphon pipes or straight drainage pipes can automatically drain water from the water collection well, saving energy and reducing slope drainage costs;

(3) The smooth drainage of groundwater in weakly permeable soil slopes increases the stability of the slope and has huge economic, social and environmental benefits;

(4) Water collection wells and drainage pipes can systematically discharge groundwater into the interception drainage ditch of the interception and drainage platform downstream of the slope, which can effectively solve the problem of reduced strength of the soil at the lower part of the slope due to the infiltration of groundwater from the upper part;

(5) Engineering application tests and research show that the combined seepage drainage system designed by the present invention has a compact structure, long-lasting life, stability and firmness, easy implementation, and energy saving. It can effectively realize the smooth centralized drainage of groundwater on weakly permeable soil slopes and prevent slopes from being drained. It can prevent surface soil layer saturation and erosion damage and increase the long-term stability of slopes. It can be used in groundwater treatment projects of weakly permeable soil layers on soil slopes in open-pit mines, construction, water conservancy, transportation and other industries.

Description of the drawings

Figure 1 is a schematic plan view of a combined drainage and seepage system designed for a method of controlling groundwater hazards in weakly permeable soil slopes according to the present invention;

Figure 2 is a schematic cross-sectional view of a combined drainage and seepage system designed for a method of controlling groundwater hazards in weakly permeable soil slopes according to the present invention.

Reference symbols: 1-upper level platform; 2-slope; 3-water collection well platform; 4-interception and drainage platform; 5-water collection well; 6-aquitard layer, permeability coefficient is greater than 10 ^-4 ; 7-weak aquitard layer , the permeability coefficient is less than 10 ^-4 ; 8-horizontal drainage flower tube; 9-water collection well sealing cover; 10-vacuum air extraction pipe; 11-vacuum air extraction pump; 12-deep well pump; 13-siphon water supply pipe; 14-control valve ; 15-siphon pipe; 16-siphon regulating valve; 17-vertical drainage flower tube; 18-vertical drainage pipe sealing section; 19-vertical drainage pipe sealing cover; 20-one-way valve or electric control valve; 21-Straight drain pipe.

Detailed ways

In order to further describe the present invention, a method for controlling groundwater disasters in weakly permeable soil slopes according to the present invention will be described in further detail below with reference to the accompanying drawings.

From the schematic cross-sectional view of the combined drainage system designed by the method for controlling groundwater hazards in weakly permeable soil layer slopes according to the present invention shown in Figure 2 and combined with Figure 1, it can be seen that the method for controlling groundwater disasters in weakly permeable soil layer slopes according to the present invention, The weakly permeable soil slope is provided with an upper level platform 1, a water collection well platform 3, and an interception and drainage platform 4 from top to bottom. The combined seepage drainage system is composed of a three-dimensional seepage drainage system, a vacuum assisted drainage system, and a siphon/direct drainage system:

The three-dimensional seepage drainage system includes horizontal seepage drainage flower tubes 8, vertical seepage drainage flower tubes 17, and water collection wells 5. The vertical seepage drainage flower tubes 17 are located in the upper level platform 1 and pass through different seepage drainage tubes from top to bottom. The weak water permeable layer 7 and the water permeable layer 6; the water collection well 5 is vertically arranged in the water collection well platform 3; the horizontal drainage flower pipe 8 extends horizontally to the upper level according to a slope of 1 to 2% In the stratum below the platform 1, the upstream of the horizontal seepage drainage flower tube 8 and the lower end of the vertical seepage drainage flower tube 17 are in the same stratum, and the lower end of the horizontal seepage drainage flower tube 8 is connected with the lower part of the water collection well 5; the water collection well 5 is connected by the wellbore It is composed of a water collection well sealing cover 9; the vertical seepage flower pipe 17 is made of steel pipe, engineering plastic pipe or seepage blind ditch material with an opening rate of not less than 10%, and the upper end of the vertical seepage flower pipe 17 extends out of the ground. The sealing section 18 of the vertical seepage pipe should be sealed with sealant or expansion cement slurry within a depth of 2m from the ground surface; the horizontal seepage drainage pipe 8 should be made of steel pipe or engineering plastic pipe with an opening rate of not less than 10% in the upper half of the pipe. The horizontal drainage flower pipe 8 is sealed with structural glue or expansion cement slurry around the well wall section pipe of the water collection well 5 .

The vacuum drainage system is composed of a vacuum pump 11 and a vacuum pipe 10. The vacuum pump 11 is fixed on the water collection well sealing cover 11. The upper end of the vacuum pipe 10 is connected to the vacuum pump 11, and the vacuum pipe 10 passes through it. The water collection well sealing cover 9 and the lower end of the vacuum exhaust pipe 10 extend into the lower part of the water collection well 5. The vacuum drainage system maintains the vacuum degree of the set water column in the water collection well 5.

The siphon/straight drainage system includes two modes: gravity straight drainage and siphon drainage: when the gravity straight drainage is adopted, the straight drainage system includes water guide holes and straight drainage pipes 21. The water guide is The hole is located at the bottom of the water collection well 5 close to the side of the slope 2. The slope of the water conduction hole is 2 to 5%. The straight drainage pipe 21 is located in the slope body of the lower part of the water collection well platform 3. The water inlet of the straight drainage pipe 21 Connected to the water guide hole, a one-way valve or an electric control valve 20 is installed on the straight drainage pipe 21. The vertical distance between the inlet of the straight drainage pipe 21 and the outlet of the horizontal drainage flower pipe 8 is not less than 8m. The straight drainage pipe 21 The water outlet section extends from the slope 2 down to the intercepting drainage platform 4 and then outwards to the outlet position; when the siphon drainage method is adopted, the siphon drainage system includes a deep well pump 12, a siphon pipe 15, and a siphon water supply pipe 13. The deep well pump 12 is installed on the collector. At the bottom of the water well 5, the water inlet end of the siphon pipe 15 extends into the lower part of the water collection well 5 along the inner wall of the water collection well 5. A control valve 14 is provided on the siphon pipe 15 located outside the water collection well sealing cover 9. The water outlet section of the siphon pipe 15 passes through the water collection well platform. 3. The slope 2 goes down to the drainage platform 4 and then extends outward to the outlet position. The deep well pump 12 is connected to the water supply port of the siphon water supply pipe 13. The siphon water supply pipe 13 passes through the water collection well sealing cover 9 and then connects to the water supply port through the control valve 14. The siphon 15 is connected near the water collecting well sealing cover 9; the total height H1 of the water collecting well 5 should be less than the vertical height H2 from the wellhead of the water collecting well 5 to the outlet of the straight drainage pipe 21/siphon pipe 15, and the difference in vertical height between the two should be greater than 15m. . The part of the siphon pipe 15 located inside the water collecting well 5 and passing through the water collecting well sealing cover 9 is made of steel pipe or engineering plastic pipe, and is sealingly connected with the water collecting well sealing cover 9; the siphon pipe 15 is located at the junction of the slope 2 and the drainage platform 4. Siphon regulating valve 16.

In practical applications, the diameter of the vertical seepage drainage pipe 17 is not greater than 75mm, and the diameter of the straight drainage pipe 21 is not greater than 90mm; the length of the siphon pipe 15 is determined by the well depth and outlet position of the water collection well 5, but the entrance and outlet of the siphon pipe 15 The height difference between them is determined by the head difference required to achieve gravity flow, but shall not be less than 15m.

A groundwater disaster control method for weakly permeable soil slopes of the present invention adopts the following steps for construction:

1) Based on hydrological and geological data, determine the scope of groundwater treatment on weakly permeable soil slopes; determine the number and layout locations of combined drainage systems based on the location of weakly permeable soil slopes and the size of the treatment area; based on the permeability of the soil layer, Based on the amount of water inflow, determine the number of vertical drainage pipes 17, horizontal drainage pipes 8, and straight drainage pipes 21; determine the depth and diameter of the water collection well 5 based on geological data and construction technology;

2) Construct the water collection well 5 in the water collection well platform 3, and leave a mark at the position of the highly permeable soil layer with a permeability coefficient greater than 10 ^-4 . At the same time, construct a vertical well 5 in the first level platform 1 upstream of the water collection well 5. The vertical drainage flower tube 17 is passed through the weakly permeable layer 7 and the water permeable layer 6 with different permeability, and the upper end of the vertical drainage flower tube 17 is blocked. The blocking section of the vertical drainage flower tube 17 is not less than 2m. ;

3) After the construction of the water collection well 5 reaches the design depth, construct the straight drainage pipe 21 in the direction of the slope 2 of the water collection well 5. The slope ratio of the straight drainage pipe 21 is 2 to 5%. The construction of each straight drainage pipe 21 is completed. Finally, install a one-way valve or electric control valve 20 on the straight drainage pipe 21, and seal the intersection between the straight drainage pipe 21 and the wall of the water collection well 5;

Or install the deep well pump 12, siphon pipe 15 and control valve 14, and put the drainage system in working condition;

4) According to the marks left during the construction of the water collection well 5, construct the horizontal drainage flower pipe 8 from bottom to top, and make the horizontal drainage flower pipe 8 pass near the soil layer where the vertical drainage flower pipe 17 is located; each horizontal drainage pipe After the construction of the seepage flower pipe 8 is completed, seal the intersection between the horizontal seepage flower pipe 8 and the well wall of the water collection well 5;

5) After the installation of the horizontal drainage flower pipe 8 is completed, install the vacuum exhaust pipe 10, and finally install the vacuum exhaust pump 11, and seal the water collection well sealing cover to put the entire system in a normal pressure drainage state;

6) After the above project is completed, the vertical drainage flower pipe 17 will drain the groundwater in the weakly permeable layer 7 and the stagnant water in the permeable layer 6 in the upper soil layer to the horizontal drainage flower pipe 8 or the soil where the horizontal drainage flower pipe 8 is located. layer, and then discharged to the water collection well 5 by the horizontal drainage flower pipe 8, and then discharged to the outside of the slope by the straight drainage pipe 21 or the siphon 15, thereby realizing normal pressure drainage of the weakly permeable soil layer;

7) After normal pressure seepage drainage works normally, close the control valve 14 on the siphon pipe 15 and open the vacuum pump 11 installed on the water collecting well sealing cover 9 at the upper end of the water collecting well 5. When the air pressure in the water collecting well 5 is lower than the air pressure outside the well, When, negative pressure drainage of weakly permeable soil layers is achieved;

8) When the air pressure in the water collection well 5 is close to vacuum, turn on the deep well pump 12 and open the control valve 14 on the siphon pipe 15. When the siphon pipe 15 drains water normally, close the vacuum pump 11 and the deep well pump 12 to achieve negative pressure discharge of the entire system. Seepage and gravity drainage.

The principle of the method for controlling groundwater disasters in weakly permeable soil slopes according to the present invention is as follows: the vertical seepage drainage pipe 17 connects the groundwater of the weakly permeable layer 7 with weak permeability and the strong permeable layer 6 in the upper soil layer. The stagnant water is discharged to the horizontal drainage pipe 8 or the soil layer where it is located, and then is discharged from the horizontal drainage pipe 8 to the water collection well 5, and then is discharged to the outside of the slope by the straight drainage pipe 21 or the siphon 15, thereby achieving weak permeability Normal pressure drainage of soil layer.

On the basis of normal pressure drainage, close the control valve 14 on the siphon pipe 15 (or the one-way valve or electric control valve 20 on the straight drainage pipe 21), and open the water collecting well sealing cover 9 installed at the upper end of the water collecting well 5. The vacuum pump 11 realizes negative pressure drainage of weakly permeable soil layers when the air pressure in the water collecting well 5 is lower than the air pressure outside the well.

When the vertical seepage drainage flower tube 17 doubles as a groundwater level observation hole, a vertical seepage drainage tube sealing cover 19 is added to the mouth of the vertical seepage drainage flower tube 17 for sealing.

When the air pressure in the water collection well 5 is close to vacuum, turn on the deep well pump 12 and open the control valve 14 on the siphon pipe 15. When the siphon water supply pipe drains water normally, close the vacuum pump 11 and the deep well pump 12, or open the direct drain pipe 21. One-way valve or electric control valve 20 realizes negative pressure drainage and gravity drainage of the entire system to save energy.

The method for controlling groundwater disaster in weakly permeable soil slopes of the present invention can utilize the head pressure difference in the pipe or the pressure difference compensated by the deep well pump to realize automatic drainage, and maintain a certain degree of vacuum in the sealed three-dimensional drainage system to achieve savings. For energy purposes, the system is divided into gravity direct drainage and siphon drainage.

When the horizontal distance between the bottom of the water collection well 5 and the side slope 2 of the same elevation is short (less than 80m), construct a water guide hole at the bottom of the water collection well 5 with a slope of 2 to 5%, and install 21 straight drainage pipes, One-way valve or electric control valve 20, the water in the water collection well 5 overcomes the vacuum resistance and is discharged by gravity; when the horizontal distance between the bottom of the water collection well 5 and the slope surface 2 is far (more than 80m), install a deep well at the bottom of the water collection well 5 The pump 12 replenishes water through the deep well pump 12 when the siphon water replenishing pipe 5 has insufficient water. When the siphon pipe 15 operates normally, the deep well pump 12 stops working.

It should be noted that the terms "upper", "lower", "left", "right", "inner", "outer", "front", "back", "top/bottom", etc. in the present invention refer to The orientation or positional relationship is based on the orientation or positional relationship shown in the drawings, which are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the components or elements referred to must have a specific orientation, be constructed in a specific orientation, and operations and therefore should not be construed as limitations of the invention.

The invention is a method for controlling groundwater disasters in weakly permeable soil slopes with the purpose of accelerating soil drainage and improving the overall stability of soil slopes. It has been used in a moraine soil slope drainage project in a large-scale vanadium titanium magnetite mine. get applied. The application results show that under the same geological conditions, compared with the original hydraulic head difference of 24m, the water output increased by 15 to 25%, effectively eliminating groundwater in low-permeability soil slopes and ensuring the stability of the slope and the safety of the stope. safe operation.

Claims

A method for controlling groundwater disasters on a weakly permeable soil slope. The weakly permeable soil slope is provided with an upper level platform (1), a water collection well platform (3), and an interception and drainage platform (4) from top to bottom. , the water collection well (5) is installed vertically in the water collection well platform (3), which is characterized by adopting the following technical solutions:

1) Based on hydrological and geological data, determine the scope of groundwater treatment on weakly permeable soil slopes; determine the number and layout locations of combined drainage systems based on the location of weakly permeable soil slopes and the size of the treatment area; based on the permeability of the soil layer, According to the amount of water inflow, determine the number of vertical drainage flower tubes (17), horizontal drainage flower tubes (8), and straight drainage pipes (21); determine the depth and well diameter of the water collection well (5) based on geological data and construction technology ;

2) The combined seepage drainage system is composed of a three-dimensional seepage drainage system, a vacuum assisted drainage system, and a siphon/direct drainage system:

The three-dimensional drainage system includes a horizontal drainage flower tube (8), a vertical drainage flower tube (17), and a water collection well (5). The vertical drainage flower tube (17) is located on the upper platform (1). inside and through the weakly permeable layer (7) and the permeable layer (6) with different permeabilities from top to bottom; the water collection well (5) is vertically arranged in the water collection well platform (3); the horizontal drainage The seepage flower pipe (8) extends horizontally into the stratum below the upper level platform (1) according to a slope of 1 to 2%. The upstream of the horizontal seepage flower pipe (8) is at the lower end of the vertical seepage flower pipe (17). In the same stratum, the lower end of the horizontal drainage flower pipe (8) is connected with the lower part of the water collection well (5); the water collection well (5) is composed of a wellbore and a water collection well sealing cover (9);

The vacuum drainage system is composed of a vacuum pump (11) and a vacuum pipe (10). The vacuum pump (11) is fixed on the water collecting well sealing cover (11), and the upper end of the vacuum pipe (10) is connected to the vacuum pump. The air pump (11) is connected, the vacuum pumping pipe (10) passes through the water collecting well sealing cover (9), the lower end of the vacuum pumping pipe (10) extends into the lower part of the water collecting well (5), and the vacuum drainage system keeps the water collecting well (5) Set the vacuum degree of the water column;

When the horizontal distance between the bottom of the water collection well (5) and the slope surface (2) of the same elevation is less than 75m, a self-flow direct drainage system is adopted. The direct drainage system includes a water guide hole and a direct drainage pipe (21). The water guide hole is located at the bottom of the water collection well (5) near the side of the slope (2), and the straight drainage pipe (21) is located in the slope body at the lower part of the water collection well platform (3). The straight drainage pipe (21) The water inlet of 21) is connected with the water guide hole, and the water outlet section of the straight drainage pipe (21) extends from the slope (2) downward to the intercepting drainage platform (4) and then extends outward to the outlet position;

When the horizontal distance between the bottom of the water collection well (5) and the slope of the same elevation is >85m, a siphon drainage system is used; the siphon drainage system includes a deep well pump (12), a siphon pipe (15), and a siphon water supply pipe (13). The deep well pump (12) is installed at the bottom of the water collection well (5), and the water inlet end of the siphon pipe (15) extends along the inner wall of the water collection well (5) to the lower part of the water collection well (5). The siphon pipe (15) is provided with a control valve (14). The water outlet section of the siphon pipe (15) passes through the water collection well platform (3) and the slope (2) downward to the interception and drainage platform (4) and then extends outward to the outlet position. The deep well pump (12) is connected to the water supply port of the siphon water supply pipe (13). The siphon water supply pipe (13) passes through the water collection well sealing cover (9) and then passes through the control valve (14) and the siphon pipe (15) at the water collection well sealing cover (15). 9) Nearby connections;

When the horizontal distance between the bottom of the water collection well (5) and the slope surface of the same elevation is between 75 and 85m, it is determined to adopt one of the self-flow direct drainage system and the siphon drainage system based on the difficulty of construction and construction cost.
A groundwater disaster control method for weakly permeable soil slopes according to claim 1, characterized in that: a one-way valve or an electric control valve (20) is installed on the straight drainage pipe (21); The lower end of the vertical drainage pipe (17) is located near the horizontal drainage pipe (8), and the distance between the two is no more than 1m; the entrance of the straight drainage pipe (21) is located at a distance from the horizontal drainage pipe (8) )’s exit vertical distance shall not be less than 8m.
A method for controlling groundwater hazards in weakly permeable soil slopes according to claim 2, characterized in that the following steps are used for construction:

1) Construct the water collection well (5) in the water collection well platform (3), and leave a mark at the position of the highly permeable soil layer with a permeability coefficient greater than 10 -3 . At the same time, place a mark above the upstream of the water collection well (5). Construct a vertical seepage flower pipe (17) in the level platform (1) to pass through the weakly permeable layer (7) and permeable layer (6) with different permeability, and seal the vertical seepage flower pipe (17) At the upper end, the vertical seepage drainage flower tube (17) has a sealing section of not less than 2m;

2) After the construction of the water collection well (5) reaches the design depth, construct a straight drainage pipe (21) in the direction of the water collection well (5) close to the slope (2). The slope ratio of the straight drainage pipe (21) is 2 to 5%. , after the construction of each straight drainage pipe (21) is completed, install a one-way valve or electric control valve (20) on the straight drainage pipe (21), and seal the straight drainage pipe (21) and the water collection well (5 )The shaft wall handover part;

Or install the deep well pump (12), siphon pipe (15) and control valve (14), and keep the drainage system in working condition;

3) According to the marks left during the construction of the water collection well (5), construct the horizontal drainage flower pipe (8) from bottom to top, and make the horizontal drainage flower pipe (8) pass through the position of the vertical drainage flower pipe (17) Near the soil layer; after the construction of each horizontal drainage flower tube (8) is completed, seal the intersection between the horizontal drainage flower tube (8) and the well wall of the water collection well (5);

4) After the installation of the horizontal seepage flower pipe (8) is completed, install the vacuum exhaust pipe (10), and finally install the vacuum pump (11), and seal the water collection well sealing cover so that the entire system is in a normal pressure drainage state;

5) After the above project is completed, the vertical drainage flower tube (17) will drain the groundwater in the weakly permeable layer (7) and the stagnant water in the aquitard layer (6) in the upper soil layer to the horizontal drainage flower tube (8) or horizontal The soil layer where the drainage flower tube (8) is located is then drained to the water collection well (5) by the horizontal drainage flower tube (8), and then discharged to the outside of the slope by the straight drainage pipe (21) or the siphon pipe (15), thereby realizing Normal pressure drainage of weakly permeable soil layers;

6) After normal pressure seepage drainage works normally, close the control valve (14) on the siphon pipe (15) and start the vacuum pump (11) installed on the water collecting well sealing cover (9) at the upper end of the water collection well (5). When the air pressure inside the water collection well (5) is lower than the air pressure outside the well, negative pressure drainage of weakly permeable soil layers is achieved;

7) When the air pressure in the water collection well (5) is close to vacuum, turn on the deep well pump (12) and open the control valve (14) on the siphon pipe (15). When the siphon pipe (15) drains water normally, close the vacuum pump (11) and deep well pump (12) to realize negative pressure drainage and gravity drainage of the entire system.
A groundwater disaster control method for weakly permeable soil slopes according to claim 1, 2 or 3, characterized in that: the total height H1 of the water collection well (5) should be less than the distance from the wellhead of the water collection well (5) to the straight drainage pipe (21)/The vertical height H2 of the outlet of the siphon (15), and the difference in vertical height between the two should be greater than 15m.
A method for controlling groundwater disasters in weakly permeable soil slopes according to claim 4, characterized in that: the diameter of the vertical seepage drainage pipe (17) is not greater than 75mm, and the diameter of the straight drainage pipe (21) is not greater than 75mm. 90mm; the length of the siphon pipe (15) is determined by the well depth and outlet position of the water collection well (5), and the height difference between the entrance and outlet of the siphon pipe (15) is determined by the head difference required to achieve gravity flow, but shall not be less than 15m; as mentioned The vertical seepage drainage flower tube (17) adopts steel pipes, engineering plastic pipes or blind drainage ditch materials with an opening rate of not less than 10%. The upper end of the vertical seepage drainage flower tube (17) extends out of the ground. Use sealant or expansion cement slurry to seal within 2m to form a vertical drainage pipe sealing section (18).
A method for controlling groundwater disasters in weakly permeable soil slopes according to claim 5, characterized in that: the horizontal seepage drainage flower pipe (8) adopts a steel pipe with an opening rate of not less than 10% in the upper half pipe or Engineering plastic pipes and horizontal drainage flower pipes (8) are sealed with structural glue or expansion cement slurry around the well wall section of the water collecting well (5).
A groundwater disaster control method for weakly permeable soil slopes according to claim 6, characterized in that: the siphon (15) is located inside the water collection well (5) and passes through the water collection well sealing cover (9) Use steel pipes or engineering plastic pipes and seal them with the water collection well sealing cover (9).
A method for controlling groundwater disasters in weakly permeable soil slopes according to claim 7, characterized in that: the upper end of the vertical drainage flower pipe (17) is sealed with cement slurry or chemical slurry; The space between the water collection well sealing cover (9) and the water collection well (5) is sealed with asphalt or sealing glue; the space between the vacuum exhaust pipe (10) and the water collection well sealing cover (9) is sealed with asphalt or sealing glue.
A method for controlling groundwater disasters in weakly permeable soil slopes according to claim 8, characterized in that: the work and conversion of the entire combined seepage drainage system are realized automatically starting and switching under an automatic control system composed of sensors and single-chip microcomputers. closure.