Acidic soil foundation treatment system and method

Abstract

The present invention provides a system and method for treating acidic soil foundations. The treatment system includes a water injection tank, a neutralization tank, and a cement-soil retaining wall surrounding the acidic soil foundation to be treated. A pumping well and a pressure well are drilled in the acidic soil foundation area to be treated. A pumping filter pipe and a pump are installed in the pumping well. A gravel layer is backfilled between the filter pipe and the pumping well. The pump is connected to the neutralization tank via the pumping pipe. A permeable pipe is installed in the pressure well, and a water pressure device is installed in the permeable pipe. Gravel is filled between the lower part of the permeable pipe and the soil well wall, and clay is filled at the upper part. The water pressure device includes a piston that blocks the permeable pipe. The piston is provided with inlets for clean water and neutralizing liquid. The clean water inlet is connected to the water injection tank, and the neutralizing liquid inlet is connected to the neutralization tank. The present invention effectively addresses the corrosive effects of groundwater and acidic soil on foundations in acid-contaminated areas, thereby improving the pH value of groundwater and soil in the acid-contaminated area.

Description

Technical Field

[0001] The present invention relates to the field of geotechnical engineering, and in particular to a system and method for treating acidic soil foundation. Background Art

[0002] An industrial plant located in a coastal area suffered a waste acid overflow at its neutralization station. The overflowing acid flowed onto the curbstones outside the wastewater pool, corroding the joints and creating large cracks. The acid then seeped into the ground, causing extensive contamination of the plant's foundation soil. The plant now needed to be renovated and additional structures constructed. The foundations of these structures were buried approximately 5 meters deep. To prevent the acidic soil from corroding the foundations of the new structures, the acidic soil within the structure's foundations needed to be treated.

[0003] The existing treatment methods generally require that field surveys and laboratory tests be conducted before the treatment of acidic foundation soil in order to obtain information on the types, contents, and diffusion levels of the main pollutants, and to formulate corresponding treatment plans. Then, soil neutralization is carried out in the area, mainly by using alkaline substances such as lime, soda ash, and calcium hydroxide. By evenly spreading the neutralizer in the contaminated area, it reacts chemically with the underground acidic substances to neutralize the acidic soil and reduce the degree of soil pollution. Finally, natural or artificially planted plants with strong adaptability and the ability to effectively absorb and metabolize pollutants, such as locust trees, poplars, and loosestrife, are used. After the foundation section is adjusted to a flat shape through mechanized wheeling and shoveling, vegetation restoration is carried out on the surface area. In order to prevent acidic substances from corroding the foundation again, cement slurry grouting, water injection pumps, and other methods are also used to waterproof the underground and fill foundation gaps to avoid underground leakage problems.

[0004] The existing treatment methods mainly isolate the acid in the acidic foundation, but do not extract the acid in the soil. Therefore, the time period for subsequent repair with a neutralizer is too long, and deep soil repair cannot be achieved. There are certain limitations. In this regard, this application provides a treatment system and method for acidic soil foundation. Summary of the Invention

[0005] In order to solve the above problems, the present invention provides a system and method for treating acidic soil foundation, which can effectively solve the impact of acidic soil on the foundation of the structure and improve the bearing capacity of the foundation soil to a certain extent.

[0006] In order to achieve the above technical objectives, the present invention provides a treatment system for acidic soil foundation, characterized in that: the treatment system includes a water injection tank, a neutralization tank, a circle of cement soil retaining wall arranged outside the range of the acidic soil foundation to be treated, and a pumping well and a pressure well arranged within the range of the acidic soil foundation to be treated; the pumping well and the pressure well are wellbores drilled directly in the soil layer of the acidic soil foundation, a pumping filter pipe with an outer diameter smaller than the inner diameter of the pumping well is provided in the pumping well, a pumping pump is provided in the filter pipe, a first crushed stone layer is filled between the filter pipe and the well wall of the soil layer of the pumping well, and the pumping pump is connected to the neutralization tank through a pumping pipe; a permeable pipe with an outer diameter smaller than the inner diameter of the pressure well is provided in the pressure well, a permeable hole is opened in the middle and lower part of the permeable pipe, a second crushed stone layer is filled between the outer wall of the permeable hole area in the middle and lower part of the permeable pipe and the well wall of the soil layer, a clay layer is filled between the outer wall of the upper part of the permeable pipe without permeable holes and the well wall of the soil layer, and a water pressure device is provided in the permeable pipe;

[0007] The water pressure device includes a water pressure pipe embedded in a permeable pipe and a piston located in the water pressure pipe. A piston control mechanism is provided at the handle end of the piston. A clean water injection port and a neutralizing liquid injection pipe are provided on the piston. The upper ends of the clean water injection port and the neutralizing liquid injection pipe are respectively connected to the water injection tank and the neutralizing tank. The lower ends of the clean water injection port and the neutralizing liquid injection pipe both pass through the piston and lead to the bottom of the piston. Clean water and neutralizing liquid are respectively injected into the lower part of the water pressure pipe through the clean water injection port and the neutralizing liquid injection pipe. Under the control of the piston control mechanism, the piston moves up and down in the water pressure pipe to pressurize the clean water and neutralizing liquid in the lower part of the water pressure pipe and drive them into the soil.

[0008] The better technical solution of the present invention is: the pressure water pipe is adapted to the permeable pipe, the upper part of the pressure water pipe is a solid pipe, and is in sealed contact with the permeable pipe, the lower layer and the permeable pipe realize water flow conduction, and a cylindrical pipe body support tube matching its inner diameter is provided on the lower layer of the pressure water pipe, and permeable holes are provided at the lower end and side of the pipe body support tube, and a screw rod passing through the pipe body support tube is provided under the piston; the pipe mouth of the pressure water pipe is provided with a clean water storage tank, and when the piston descends, the clean water in the clean water storage tank will be deposited above the piston to increase the pressure and reduce the load of the piston pushing mechanism; when the piston ascends, the clean water inlet is opened, and the clean water in the clean water storage tank is added to the area of ​​the pressure water pipe below the piston; the upper end of the neutralization liquid injection pipe extends out of the pressure water pipe and the clean water storage tank and is connected with the neutralization tank, and the clean water storage tank is connected with the water injection tank through a pipeline.

[0009] A preferred technical solution of the present invention is as follows: the ports of the clean water injection port and the neutralizing liquid injection pipe located at the lower part of the piston are respectively provided with a one-way valve, and when the piston moves upward, the one-way valve is controlled to open to inject clean water and neutralizing liquid, and when the piston moves downward, the one-way valve is closed. At this time, the downward movement of the piston generates pressure, and the mixed pressure of clean water and neutralizing liquid is pressed into the soil.

[0010] The preferred technical solution of the present invention is as follows: there are multiple pumping wells and water pressure wells, and the multiple pumping wells are dispersed among the multiple water pressure wells; the structure of each pumping well is exactly the same, and a pumping pump and a pumping pipe are evenly distributed in the well, and the pumping pipes of the multiple pumping wells are connected to the neutralization tank through an external pumping pipe network; the structure of each water pressure well is exactly the same, and a permeable pipe and a water pressure device are evenly distributed in the well, and the clean water injection ports of the multiple water pressure devices are connected to the water injection tank through the water pressure pipe network; a pressure gauge and a switch valve are installed at a position where the water pressure pipe network is 0.5 to 1.0 m away from the wellhead of each water pressure well.

[0011] A better technical solution of the present invention is as follows: the neutralization tank is provided with an alkali liquid neutralization device, the neutralization tank is connected to the water injection tank through a circulation pipe, and the circulation pipe is provided with a first control valve; the alkali liquid neutralization device includes an alkali liquid storage device connected to the neutralization tank pipeline and a pH value detection device arranged in the neutralization tank, a second control valve is provided on the pipeline connecting the alkali liquid storage device and the neutralization tank, the pH value detection device is connected to the second control valve signal, and when the pH value in the neutralization tank is lower than 8, the second control valve is opened, and the alkali liquid storage device inputs alkali liquid into the neutralization tank; when the liquid pH in the neutralization tank is greater than 9, the second control valve is automatically closed.

[0012] The preferred technical solution of the present invention is as follows: the cement soil retaining wall is composed of cement soil mixing piles with a diameter of 400 to 600 mm interlocked with each other, and the interlocking width is not less than 150 mm; the water pressure well is drilled by a drilling rig, with a hole diameter of 30 cm to 40 cm, and a water permeable pipe with a diameter of 20 cm to 40 cm is placed in the hole. The water permeable pipe adopts a steel pipe with a wall thickness of 3 to 5 mm, and a plum blossom-shaped water permeable hole is processed at the position below 1 / 3L of the length of the steel pipe, and the water permeable hole has a diameter of 3 to 10 mm; the second gravel layer adopts gravel with a particle size of 5 to 15 mm.

[0013] The preferred technical solution of the present invention is as follows: the pumping well is mechanically drilled with a drilling rig, the hole diameter is 50-80 cm, the filter tube diameter is 40-60 cm, the first gravel layer is filled to the ground height, and the gravel particle size used is 5-15 mm.

[0014] A better technical solution of the present invention: the piston control mechanism includes a drive motor and a drive connecting rod, the drive motor is fixedly installed outside the wellhead of the water pressure well, one end of the drive connecting rod is connected to the output shaft of the drive motor, and the other end is connected to the piston hinge. Under the action of the drive motor, the drive connecting rod is controlled to extend and retract, thereby driving the piston to move up and down along the water pressure pipe.

[0015] The better technical solution of the present invention: a rotating stirring assembly is installed at the center position of the tube body support tube, the lower end of the screw rod is connected to the stirring assembly, and a return spring for supporting the piston and the tube body support tube is provided on the outside of the screw rod; the stirring assembly includes a bearing seat, a screw nut and a stirring blade are installed on the bearing seat, the screw nut cooperates with the screw rod, and when the screw rod moves up and down with the piston, it can drive the stirring blade to rotate forward and reverse.

[0016] In order to achieve the above technical objectives, the present invention also provides a method for treating an acidic soil foundation, wherein the method uses the above acidic soil foundation treatment system for treatment, and the specific steps are as follows:

[0017] (1) Construct mixing piles along the edge of the acid foundation treatment area to form a closed cement soil wall; the cement soil retaining wall is composed of cement soil mixing piles with a diameter of 400 to 600 mm that are interlocked with each other, and the interlocking width is not less than 150 mm;

[0018] (2) Evenly arrange pressure wells within the acidic base treatment range. The pressure wells are drilled mechanically with a hole diameter of 30cm to 40cm. A water pipe with a diameter of 20cm to 40cm is placed in the hole. A water hole with a diameter of 3 to 10mm is processed at the part below 1 / 3 of the length of the water pipe. Gravel with a particle size of 5 to 15mm is filled between the water hole of the water pipe and the soil layer. Clay soil is filled and compacted between the part above the water hole and the soil layer. A pressure pipe and a water pressure device are installed in the water pipe;

[0019] (3) Pumping wells are evenly arranged within the acid foundation treatment range. The pumping wells are drilled mechanically with a hole diameter of 50 to 80 cm. A filter tube with a diameter of 40 to 60 cm is placed in the hole. Gravel with a particle size of 5 to 15 mm is used to fill the space between the filter tube and the soil layer to the ground level, and a pump is placed in the filter tube;

[0020] (4) Layout and installation of pressure water and pumping pipelines: pipes with a diameter of 50-100 mm are used as pressure water pipe network and pumping pipe network. The pressure water pipe network connects the clean water injection port of the pressure water device in each pressure water well with the water injection tank, and the pumping pipe network connects the pumping pipe in each pumping well with the neutralization tank. Pressure gauges and valves are installed on the pipelines of the pressure water pipe network near each pressure water well, and the neutralization liquid injection pipe of the pressure water device in each pressure water well is connected to the neutralization tank;

[0021] (5) The acidic liquid in the acidic soil is pumped into the neutralization tank through a water pump, and alkaline liquid is added to the neutralization tank for neutralization treatment. At the same time, a liquid index detection device is installed in the neutralization tank; the alkaline neutralization liquid treated in the neutralization tank can also be pressed into the foundation soil through a water pressure pipe; and the pumped water is tested by the detection device, and the various indicators of the treated acidic foundation are tested at the same time. After the test is qualified, continue to pump water for 7-8 days until there is no groundwater infiltration in the pumping well. Let it stand for a period of time to drain the pore water in the foundation soil and wait for the soil to consolidate under its own weight;

[0022] (6) Finally, use quicklime and gravel sand in a ratio of 1:2 to 1:4 to backfill the injection holes and pumping holes to complete the treatment process of the acidic foundation.

[0023] During the treatment process, the present invention considers that the use of caustic soda as a replacement can easily lead to a more violent chemical reaction, releasing heat quickly and affecting the bearing capacity of the foundation soil. Therefore, when preparing the alkaline flushing solution, appropriate amounts of quicklime and soda ash (CaO and CaCO3) are added. The molecular formulas are: CaO + H2SO4 = CaSO4 + H2O, and CaCO3 + H2SO4 = CaSO4 + H2O + CO2. After the foundation soil acidity index meets the requirements, the present invention continues to pump water until no groundwater seeps into the pumping well within 10-15 days. The well is then left to stand for a period of time to allow the soil to consolidate under its own weight, while neutralizing the H2 in the area. ＋ Then backfill the injection holes and pumping holes with 1:3 quicklime and gravel sand to improve the strength of the foundation soil in this area.

[0024] The present invention constructs mixing piles along the edge of the acidic foundation treatment range to form a closed cement soil wall; pumping wells are evenly arranged within the acidic foundation treatment range, and the acidic liquid in the foundation soil is pumped into a neutralization tank by a high-pressure pump, and the pH of the water in the tank is tested. Water pressure holes are evenly arranged within the acidic base treatment range, and alkaline liquid is injected into the foundation soil by a water pressure device; groundwater (acidic water) is extracted by a pump and a pump pipe to guide the flow of groundwater, and alkaline flushing liquid is injected at high pressure to accelerate the flow rate of groundwater in the area and the penetration of the alkaline flushing liquid in the required direction; and under the guidance of the pumping direction, the acidic soil and acidic water in the site are chemically neutralized (H + +HO - →H2O) and reduces corrosive ions in groundwater and soil, eliminating corrosive damage to structures. The pressure well of this invention is filled with clay and compacted between the soil layer and the area above the water hole. A sealing plug is installed in the area above the water hole within the well to ensure that there will be no pressure leakage during the entire pressurized water injection process.

[0025] The present invention ensures that pressure leakage does not occur during the entire pressurized water injection process by filling and compacting a clay layer between the soil layer and the portion above the water-permeable hole of the water-pressure well. The designed water pressure device, serving as the core of the water pressure, can meet the water pressure while simultaneously switching between continuous water replenishment and water pressure through the up and down movement of the piston, thereby improving water pressure efficiency. Simultaneously, the piston pressure drives the stirring blades to stir the water and clear liquid. Clear water in the clear water storage tank is deposited above the piston, increasing pressure and reducing the load on the piston's driving mechanism.

[0026] The present invention pumps the acidic liquid in the foundation soil into a neutralization tank for treatment through a pumping well, and then injects the alkaline liquid in the neutralization tank into the foundation soil through a water pressure hole, effectively solving the corrosiveness of groundwater and acidic soil in the acid-contaminated area on the foundation, improving the pH value of groundwater and soil in the acid-contaminated area (pH=7-9), reducing the adverse factors that may appear in the future on the foundation caused by water and soil in the area, effectively solving the impact of acidic soil on the foundation of the structure, and at the same time improving the bearing capacity of the foundation soil to a certain extent. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a plan view schematic diagram of the present invention;

[0028] Figure 2 It is a schematic cross-sectional view of a cement soil sealing wall in the present invention;

[0029] Figure 3 It is a schematic cross-sectional view of a pumping well in the present invention;

[0030] Figure 4 It is a schematic cross-sectional view of a medium-pressure water well according to the present invention;

[0031] Figure 5 It is a three-dimensional schematic diagram of the water pressure device of the present invention;

[0032] Figure 6 is a cross-sectional view of the water pressure device of the present invention;

[0033] Figure 8 It is a schematic diagram of the overall structure of the medium-pressure water pipe of the present invention;

[0034] Figure 7 This is a schematic diagram of the internal structure of the water pressure device of the present invention;

[0035] Figure 9 It is a schematic diagram of the structure of the tube body support tube in the present invention.

[0036] In the figure: 1 - cement soil retaining wall, 2 - pressure well, 3 - pressure water network, 4 - pressure gauge, 5 - switch valve, 6 - pumping well, 7 - pumping network, 8 - injection tank, 9 - neutralization tank, 10 - alkali solution storage tank, 11 - pH value detection device, 12 - first gravel layer, 13 - pumping pump, 14 - pumping pipe, 15 - pumping filter pipe, 16 - pressure water pipe, 17 - second gravel layer, 18 - clay layer, 19 - return spring, 20 - Water permeable pipe, 21—drive motor, 22—circulation pipe, 23—first control valve, 24—second control valve, 25—water permeable hole, 26—piston, 2600—clean water injection port, 2601—neutralizing liquid injection pipe, 27—drive connecting rod, 28—tube body support cylinder, 29—check valve, 30—clean water storage tank, 31—screw, 32—stirring assembly, 3200—bearing seat, 3201—screw nut, 3202—stirring blade. DETAILED DESCRIPTION

[0037] The present invention will be further described below with reference to the accompanying drawings and embodiments. Figures 1 to 9 The accompanying drawings are simplified versions of the embodiments and are only used to clearly and concisely illustrate the embodiments of the present invention. The technical solutions shown in the accompanying drawings are specific solutions of the embodiments of the present invention and are not intended to limit the scope of the invention claimed for protection. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without creative work are within the scope of protection of the present invention.

[0038] In the description of the present invention, it should be understood that the terms "upper," "lower," "inner," "outer," "left," "right," etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings, or are the directions or positional relationships in which the utility model product is typically placed when in use, or are the directions or positional relationships commonly understood by those skilled in the art. These terms are intended only to facilitate the description of the present invention and to simplify the description, and are not intended to indicate or imply that the device or component referred to must have a specific direction, be constructed, or operate in a specific direction. Therefore, they should not be construed as limiting the present invention. Furthermore, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0039] The embodiment provides a system for treating acidic soil foundation, such as Figure 1 As shown, the treatment system includes a water injection tank 8, a neutralization tank 9, a circle of cement soil retaining wall 1 arranged outside the scope of the acidic soil foundation to be treated, and a pumping well 6 and a water pressure well 2 arranged within the scope of the acidic soil foundation to be treated; the pumping well 6 and the water pressure well 2 are both provided in plurality, and the plurality of pumping wells 6 are dispersedly arranged between the plurality of water pressure wells 2; Figure 2As shown, the cement soil retaining wall 1 is composed of cement soil mixing piles with a diameter of 400-600mm interlocking with each other. The interlocking width is not less than 150mm, and the length is determined according to the actual situation of the stratum. A closed cement soil wall is formed in the acid foundation soil treatment range to prevent radial replenishment of acidic liquid during the treatment process. Figure 1 As shown, the neutralization tank 9 is provided with an alkali liquid neutralization device, the neutralization tank 9 is connected to the water injection tank 8 through a circulation pipe 22, and the circulation pipe 22 is provided with a first control valve 23; the alkali liquid neutralization device includes an alkali liquid storage device 10 connected to the neutralization tank 9 pipeline and a pH value detection device 11 arranged in the neutralization tank 9, and a second control valve 24 is provided on the pipeline connecting the alkali liquid storage device 10 and the neutralization tank 9. The pH value detection device 11 is connected to the second control valve 24 signal, and when the pH value in the neutralization tank 9 is lower than 8, the second control valve 24 is opened, and the alkali liquid storage device 10 inputs alkali liquid into the neutralization tank 9; when the liquid pH in the neutralization tank 9 is greater than 9, the second control valve 24 is automatically closed.

[0040] The embodiment provides a system for treating acidic soil foundation, such as Figure 3 As shown, the pumping well 6 is drilled mechanically with a hole diameter of 50 to 80 cm. A pumping filter pipe 15 with a diameter of 40 to 60 cm is provided in the pumping well 6. A first gravel layer 12 is filled between the filter pipe 15 and the wall of the soil layer of the pumping well 6. The first gravel layer 12 is filled to the ground level. The gravel particle size used is 5 to 15 mm. A pumping pump 13 is provided in the filter pipe 15. The structure of each pumping well 6 is exactly the same. A pumping pump 13 and a pumping pipe 14 are uniformly arranged in the well. The pumping pipes 14 of multiple pumping wells 6 are connected to the neutralization tank 9 through the external pumping pipe network 7. Figure 4 As shown, the water pressure well 2 is drilled with a drilling rig, with a hole diameter of 30cm to 40cm. A water permeable pipe 20 with a diameter of 20cm to 40cm is placed in the hole. The water permeable pipe 20 is made of a steel pipe with a wall thickness of 3 to 5mm. The steel pipe has a plum blossom-shaped water permeable hole processed below 1 / 3L of its length, with a diameter of 3 to 10mm. A second gravel layer 17 is filled between the outer wall of the water permeable hole area in the lower part of the water permeable pipe 20 and the soil well wall. The second gravel layer 17 uses gravel with a particle size of 5 to 15mm. A clay layer 18 is filled between the outer wall of the area without water permeable holes in the upper part of the water permeable pipe 20 and the soil well wall. A water pressure device is provided in the water permeable pipe 20. The structure of each water pressure well 2 is exactly the same. A water pressure device and a water permeable pipe 20 are arranged in the well. The clean water injection port of the water pressure device in multiple water pressure wells 2 is connected to the external water pressure pipe network 3, and is connected to the water injection tank 8 through the water pressure pipe network 3. Figure 1 As shown, a pressure gauge 4 and a switch valve 5 are installed in the pressure water pipe network 3 at a distance of 0.5 to 1.0 m from the wellhead of each pressure water well 2.

[0041] The embodiment provides a system for treating acidic soil foundation, such as Figures 4 to 8As shown, the water pressure device includes a water pressure pipe 16 embedded in a permeable pipe 20 and a piston 26 located in the water pressure pipe 16. The handle end of the piston 26 is provided with a piston control mechanism. The piston control mechanism includes a drive motor 21 and a drive connecting rod 27. The drive motor 21 is fixedly installed outside the wellhead of the water pressure well 2. One end of the drive connecting rod 27 is connected to the output shaft of the drive motor 21, and the other end is hinged to the piston 26. Under the action of the drive motor 21, the drive connecting rod 27 is controlled to extend and retract, thereby driving the piston 26 to move up and down along the water pressure pipe 16. A clean water injection port 2600 and a neutralizing liquid injection pipe 2601 are provided on the piston 26. The purpose of the clean water injection port 2600 is to inject clean water, and the purpose of the neutralizing liquid injection pipe 2601 is to inject neutralizing liquid. The upper ends of the clean water injection port 2600 and the neutralizing liquid injection pipe 2601 are respectively connected to the water injection tank 8 and the neutralizing tank 9, and the lower ends of the clean water injection port 2600 and the neutralizing liquid injection pipe 2601 both pass through the piston 26 and lead to the bottom of the piston. Clean water and neutralizing liquid are respectively injected into the lower part of the pressure water pipe 16 through the clean water injection port 2600 and the neutralizing liquid injection pipe 2601. Under the control of the piston control mechanism, the piston 26 moves up and down in the pressure water pipe 16 to pressurize the clean water and neutralizing liquid in the lower part of the pressure water pipe 16 into the soil. The purpose of injecting the neutralizing liquid is to perform preliminary neutralization treatment on the soil acid to reduce soil pollution.

[0042] The embodiment provides a system for treating acidic soil foundation, such as Figures 4 to 8 As shown, the pipe mouth of the pressure water pipe 16 is provided with a clean water storage tank 30. When the piston 26 moves downward, the clean water in the clean water storage tank 30 will be deposited above the piston 26 to increase the pressure and reduce the load of the piston pushing mechanism; when the piston 26 moves upward, the clean water injection port 2600 is opened, and the clean water in the clean water storage tank 30 is added to the area of ​​the pressure water pipe 16 below the piston 26; the upper end of the neutralization liquid injection pipe 2601 extends out of the pressure water pipe 16 and the clean water storage tank 30 and is connected to the neutralization tank 9, and the clean water storage tank 30 is connected to the water injection tank 8 through a pipeline. The clean water inlet 2600 and the neutralizing liquid injection pipe 2601, located below the piston 26, are each equipped with a one-way valve 29. When the piston 26 moves upward, the one-way valve 29 opens to allow the injection of clean water and neutralizing liquid. When the piston 26 moves downward, the one-way valve 29 closes, generating pressure that forces the mixture of clean water and neutralizing liquid into the soil. The one-way valve 29 is electrically controlled and can be controlled automatically or manually. Pressure pumps can also be added to the clean water inlet 2600 and the neutralizing liquid inlet to inject clean water and neutralizing liquid.

[0043] The embodiment provides a system for treating acidic soil foundation, such as Figures 4 to 9As shown, the pressure water pipe 16 is adapted to the permeable pipe 20. The upper part of the pressure water pipe 16 is a solid pipe and is sealed with the permeable pipe 20. The lower layer and the permeable pipe 20 realize water flow conduction, but the pipe body itself needs to have a certain structural strength, especially the position where the lower layer conducts water. Therefore, a cylindrical pipe body support tube 28 matching its inner diameter is provided at the lower layer of the pressure water pipe 16, and permeable holes are opened at the lower end and side of the pipe body support tube 28, which can provide bottom support while ensuring water flow. A screw rod 31 is provided below the piston 26 and passes through the tube support cylinder 28. A return spring 19 is provided on the outside of the screw rod 31 for supporting the piston 26 and the tube support cylinder 28. A rotating stirring assembly 32 is installed at the center position of the tube support cylinder 28, and the lower end of the screw rod 31 is connected to the stirring assembly 32. The stirring assembly 32 includes a bearing seat 3200, and a screw nut 3201 and a stirring blade 3202 are installed on the bearing seat 3200. The screw nut 3201 cooperates with the screw rod 31. When the screw rod 31 moves up and down with the piston 26, it can drive the stirring blade 3202 to rotate forward and reverse. When the piston 26 moves downward, the piston itself can be used to move up and down to stir and mix the clean water and the neutralizing liquid (the core is to use the power source of the up and down movement of the piston).

[0044] During construction of the present invention, after all pumping wells 6 and pressure wells 2 are installed, a planar pipe network is laid out. A pressure gauge 4 and a switch valve 5 are installed 0.5 to 1.0 m from the pressure wells 2 to prevent damage to the pressure equipment caused by the increase in excess pore water pressure in the acidic soil due to continuous water pressure. Next, the injection tank 8 is constructed. Once it reaches 70% of its design strength, the injection tank pipe network is connected and installed. Considering the liquid recycling in the neutralization tank 9 to reduce water waste, a circulation pipe 22 and a first control valve are installed to ensure consistency with the entire pipe network. The alkaline liquid, after neutralization, is then fed into the acidic foundation soil through the pressure pipe network 3 and pressure well S2. During construction of the neutralization tank 9 in the present invention, once it reaches 70% of its design strength, the pipe network 7 is installed, connecting the neutralization tank 9 to each pumping well 6. An alkali solution reservoir 10 is installed outside the neutralization tank 9.

[0045] The following describes the acidic foundation treatment method according to the present invention in conjunction with a specific example. Specifically, this example involves a project located in a coastal area. A waste acid overflow accident occurred in the project area, resulting in widespread contamination of the foundation soil. The industrial plant now needs to be renovated, and the acidic foundation soil within the structure foundation area needs to be treated. The specific treatment process is as follows:

[0046] (1) Construct mixing piles along the edge of the acid foundation treatment area to form a closed cement soil wall;

[0047] (2) Evenly arrange pressure wells within the acidic base treatment range, use a drilling rig to drill holes with a diameter of 30cm to 40cm, place a steel pipe with a diameter of 20cm to 40cm in the hole, and the wall thickness of the steel pipe is 3 to 5mm. Pre-process plum blossom-shaped water holes below 1 / 3L of the steel pipe length, with a diameter of 3 to 10mm. Depending on the permeability of the formation, fill the space between the steel pipe water hole and the soil layer with gravel, with a particle size of 5 to 15mm. Fill the space between the part above the water hole and the soil layer with clay soil and compact it. Install a pressure water pipe and a pressure water device in the water pipe. The piston of the pressure water device ensures that there will be no pressure leakage during the entire pressurized water injection process.

[0048] (3) Pumping wells are evenly arranged within the acid foundation treatment range. Drilling rigs are used to drill holes with a diameter of 50 to 80 cm. Filter tubes with a diameter of 40 to 60 cm are placed in the holes. Gravel is used to fill the space between the filter tubes and the soil layer to the ground level. The grain size of the gravel is 5 to 15 mm and a pump is placed in the holes.

[0049] (4) Arrangement and installation of water injection and pumping pipelines, with a diameter of 50-100 mm, and pressure gauges and valves installed on the water pressure pipelines near the water injection wells;

[0050] (5) Set up a neutralization tank, pump the acidic liquid in the acidic soil into the neutralization tank through a water pump, and use alkaline liquid for neutralization treatment. At the same time, install a liquid index detection device in the neutralization tank; the alkaline liquid treated in the neutralization tank can also be pressed into the foundation soil through a water pressure pipe; the pumped water is tested by the detection device, and the various indicators of the treated acidic foundation are tested at the same time. After the test is qualified, continue to pump water for 7-8 days until there is no groundwater infiltration in the pumping well. Let it stand for a period of time to drain the pore water in the foundation soil and wait for the soil to consolidate under its own weight, which can effectively improve the bearing capacity of the foundation;

[0051] (6) Finally, the injection holes and pumping holes were backfilled with quicklime and gravel sand in a ratio of 1:3 to complete the treatment process of the acidic foundation. The bearing capacity of the foundation was further improved through the above method.

[0052] Through the above treatment method, not only the acidic foundation in the area is improved, but also the bearing capacity of the foundation is enhanced.

[0053] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the present invention and the claims, all of which are protected by the present invention.

Claims

1. A system for treating acidic soil foundation, characterized by: The treatment system comprises a water injection tank (8), a neutralization tank (9), a cement soil retaining wall (1) arranged outside the scope of the acidic soil foundation to be treated, and a pumping well (6) and a pressure well (2) arranged within the scope of the acidic soil foundation to be treated; the pumping well (6) and the pressure well (2) are well holes drilled directly in the soil layer of the acidic soil foundation, a pumping filter pipe (15) with an outer diameter smaller than the inner diameter of the pumping well is provided in the pumping well (6), a pumping pump (13) is provided in the filter pipe (15), and a space between the filter pipe (15) and the wall of the soil layer of the pumping well (6) is provided. A first crushed stone layer (12) is filled, and a water pump (13) is connected to the neutralization tank (9) through a water pumping pipe (14); a water permeable pipe (20) having an outer diameter smaller than the inner diameter of the water pressure well is arranged in the water pressure well (2); a water permeable hole is opened in the middle and lower part of the water permeable pipe (20); a second crushed stone layer (17) is filled between the outer wall of the water permeable hole area in the middle and lower part of the water permeable pipe (20) and the soil well wall; a clay layer (18) is filled between the outer wall of the water permeable hole-free area in the upper part of the water permeable pipe (20) and the soil well wall; a water pressure device is arranged in the water permeable pipe (20); The water pressure device comprises a water pressure pipe (16) embedded in a water permeable pipe (20) and a piston (26) located in the water pressure pipe (16). The handle end of the piston (26) is provided with a piston control mechanism. A clean water injection port (2600) and a neutralizing liquid injection pipe (2601) are provided on the piston (26). The upper ends of the clean water injection port (2600) and the neutralizing liquid injection pipe (2601) are respectively connected to the water injection tank (8) and the neutralizing tank (9). The lower ends of the clean water injection port (2600) and the neutralizing liquid injection pipe (2601) both pass through the piston (26) and lead to the bottom of the piston, and the clean water and the neutralizing liquid are respectively injected into the lower part of the pressure water pipe (16) through the clean water injection port (2600) and the neutralizing liquid injection pipe (2601). The piston (26) moves up and down in the pressure water pipe (16) under the control of the piston control mechanism to pressurize the clean water and the neutralizing liquid in the lower part of the pressure water pipe (16) into the soil; The pressure water pipe (16) is adapted to the permeable pipe (20). The upper portion of the pressure water pipe (16) is a solid pipe and is in sealed contact with the permeable pipe (20). The lower layer is connected to the permeable pipe (20) to achieve water flow conduction. A cylindrical pipe support tube (28) matching the inner diameter of the pressure water pipe (16) is provided on the lower layer of the pressure water pipe (16). The lower end and side of the pipe support tube (28) are provided with water holes (25). A screw rod (31) penetrating the pipe support tube (28) is provided below the piston (26); a clean water storage tank (30) is provided at the pipe mouth of the pressure water pipe (16). When the piston (26) moves downward, the clean water in the clean water storage tank (30) is deposited above the piston (26) to increase the pressure and reduce the load of the piston pushing mechanism; when the piston (26) moves upward, the clean water injection port (2600) is opened, and the clean water in the clean water storage tank (30) is added to the area of ​​the pressure water pipe (16) below the piston (26); the upper end of the neutralization liquid injection pipe (2601) extends out of the pressure water pipe (16) and the clean water storage tank (30) is connected to the neutralization tank (9), and the clean water storage tank (30) is connected to the water injection tank (8) through a pipeline; The ports of the clean water injection port (2600) and the neutralizing liquid injection pipe (2601) located at the lower part of the piston (26) are respectively provided with a one-way valve (29). When the piston (26) moves upward, the one-way valve (29) is controlled to open to inject clean water and neutralizing liquid. When the piston (26) moves downward, the one-way valve (29) is closed. At this time, the downward movement of the piston (26) generates pressure, and the mixed pressure of clean water and neutralizing liquid is pressed into the soil.

2. The acidic soil foundation treatment system according to claim 1, characterized in that: There are multiple pumping wells (6) and pressure water wells (2), and the multiple pumping wells (6) are dispersedly arranged between the multiple pressure water wells (2); the structure of each pumping well (6) is exactly the same, and a pumping pump (13) and a pumping pipe (14) are uniformly arranged in the well, and the pumping pipes (14) of the multiple pumping wells (6) are connected to the neutralization tank (9) through the external pumping pipe network (7); the structure of each pressure water well (2) is exactly the same, and a permeable pipe (20) and a pressure water device are uniformly arranged in the well, and the clean water injection ports (2600) of the multiple pressure water devices are connected to the injection tank (8) through the pressure water pipe network (3); a pressure gauge (4) and a switch valve (5) are installed at a position 0.5 to 1.0 m away from the wellhead of each pressure water well (2) on the pressure water pipe network (3).

3. The acidic soil foundation treatment system according to claim 1, characterized in that: The neutralization tank (9) is provided with an alkali solution neutralization device. The neutralization tank (9) is connected to the water injection tank (8) through a circulation pipe (22), and a first control valve (23) is provided on the circulation pipe (22); the alkali solution neutralization device comprises an alkali solution storage device (10) connected to the neutralization tank (9) pipeline and a pH value detection device (11) arranged in the neutralization tank (9); a second control valve (24) is provided on the pipeline connecting the alkali solution storage device (10) and the neutralization tank (9); the pH value detection device (11) is signal-connected to the second control valve (24), and when the pH value in the neutralization tank (9) is lower than 8, the second control valve (24) is opened, and the alkali solution storage device (10) inputs alkali solution into the neutralization tank (9); when the pH value of the liquid in the neutralization tank (9) is greater than 9, the second control valve (24) is automatically closed.

4. The acidic soil foundation treatment system according to claim 1, characterized in that: The cement soil retaining wall (1) is composed of cement soil mixing piles with a diameter of 400 to 600 mm interlocked with each other, and the interlocking width is not less than 150 mm; the water pressure well (2) is drilled by a drilling machine, with a hole diameter of 30 cm to 40 cm, and a water permeable pipe (20) with a diameter of 20 cm to 40 cm is placed in the hole. The water permeable pipe (20) is a steel pipe with a wall thickness of 3 to 5 mm, and a plum blossom-shaped water permeable hole is processed below 1 / 3L of the length of the steel pipe, and the water permeable hole has a diameter of 3 to 10 mm; the second crushed stone layer (17) is crushed stone with a particle size of 5 to 15 mm.

5. The acidic soil foundation treatment system according to claim 1, characterized in that: The pumping well (6) is drilled mechanically with a hole diameter of 50 to 80 cm, the filter tube (15) has a diameter of 40 to 60 cm, and the first gravel layer (12) is filled to the ground level with a gravel particle size of 5 to 15 mm.

6. The acidic soil foundation treatment system according to claim 1, characterized in that: The piston control mechanism comprises a drive motor (21) and a drive connecting rod (27). The drive motor (21) is fixedly mounted outside the wellhead of the water pressure well (2). One end of the drive connecting rod (27) is connected to the output shaft of the drive motor (21), and the other end is hingedly connected to the piston (26). Under the action of the drive motor (21), the drive connecting rod (27) is controlled to extend and retract, thereby driving the piston (26) to move up and down along the water pressure pipe (16).

7. The acidic soil foundation treatment system according to claim 1, characterized in that: A rotating stirring assembly (32) is installed at the center position of the tube support cylinder (28), the lower end of the screw rod (31) is connected to the stirring assembly (32), and a return spring (19) for supporting the piston (26) and the tube support cylinder (28) is provided on the outside of the screw rod (31); the stirring assembly (32) includes a bearing seat (3200), a screw rod nut (3201) and a stirring blade (3202) are installed on the bearing seat (3200), and the screw rod nut (3201) cooperates with the screw rod (31), and when the screw rod (31) moves up and down with the piston (26), it can drive the stirring blade (3202) to rotate forward and reverse.

8. A method for treating acidic soil foundation, characterized by: The treatment method is performed using the acidic soil foundation treatment system according to any one of claims 1 to 7, and the specific steps are as follows: (1) Construct mixing piles along the edge of the acid foundation treatment area to form a closed cement soil wall; the cement soil retaining wall is composed of cement soil mixing piles with a diameter of 400 to 600 mm that are interlocked with each other, and the interlocking width is not less than 150 mm; (2) Evenly arrange pressure wells within the acidic base treatment range. The pressure wells are drilled mechanically with a hole diameter of 30cm to 40cm. A water pipe with a diameter of 20cm to 40cm is placed in the hole. A water hole with a diameter of 3 to 10mm is processed at the part below 1 / 3 of the length of the water pipe. Gravel with a particle size of 5 to 15mm is filled between the water hole of the water pipe and the soil layer. Clay soil is filled and compacted between the part above the water hole and the soil layer. A pressure pipe and a water pressure device are installed in the water pipe; (3) Pumping wells are evenly arranged within the acid foundation treatment range. The pumping wells are drilled mechanically with a hole diameter of 50 to 80 cm. A filter tube with a diameter of 40 to 60 cm is placed in the hole. Gravel with a particle size of 5 to 15 mm is used to fill the space between the filter tube and the soil layer to the ground level, and a pump is placed in the filter tube; (4) Layout and installation of pressure water and pumping pipelines: pipes with a diameter of 50-100 mm are used as pressure water pipe network and pumping pipe network. The pressure water pipe network connects the clean water injection port of the pressure water device in each pressure water well with the water injection tank, and the pumping pipe network connects the pumping pipe in each pumping well with the neutralization tank. Pressure gauges and valves are installed on the pipelines of the pressure water pipe network near each pressure water well, and the neutralization liquid injection pipe of the pressure water device in each pressure water well is connected to the neutralization tank; (5) The acidic liquid in the acidic soil is pumped into the neutralization tank through a water pump, and alkaline liquid is added to the neutralization tank for neutralization treatment. At the same time, a liquid index detection device is installed in the neutralization tank; the alkaline neutralization liquid treated in the neutralization tank is pressed into the foundation soil through a water pressure pipe; the pumped water is tested through the detection device, and various indicators of the treated acidic foundation are tested at the same time. After the test is qualified, continue to pump water for 7-8 days until there is no groundwater infiltration in the pumping well. Let it stand for a period of time to drain the pore water in the foundation soil and wait for the soil to consolidate under its own weight; (6) Finally, fill the injection holes and pumping holes with quicklime and gravel sand in a ratio of 1:2 to 1:4 to complete the treatment process of the acidic foundation.

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