Method and device for electroosmosis dehydration of soil body

Abstract

The invention relates to the field of soil electroosmosis dehydration, and particularly discloses a soil electroosmosis dehydration method and device, the device comprises a power supply, a plurality of perforated conductive pipes, a plurality of drainage pipes and a vacuum pump, liquid level meters are arranged in the perforated conductive pipes, and control valves and check valves are arranged on the drainage pipes. The push type construction method is adopted, construction is gradually propelled from the shore side to the center of the to-be-consolidated area, consolidation is conducted in sequence, and the problem that large-area soft soil consolidation construction is difficult is solved. The perforated conductive pipe and the drainage pipe are matched with the vacuum pump to replace a surface coating film in traditional vacuum preloading drainage, meanwhile, by controlling the opening and closing states of the check valve and the control valve, it can be guaranteed that accumulated water in the perforated conductive pipe can be pumped and drained in time, and the situation that the drainage effect is affected due to air inflow in the drainage pipe can also be avoided.

Description

Technical Field

[0001] The present application relates to the field of soil electroosmotic dehydration, and in particular to a method and device for soil electroosmotic dehydration. Background Art

[0002] There are five main electrical phenomena in soil, namely: flow potential, migration potential, electroosmosis, ion migration and electrophoresis. The soil electrokinetic technology developed by using soil electrical phenomena is a platform technology that realizes water migration, ion migration, electrochemical reaction, etc. in the soil by passing direct current into the soil. This technology can be applied to many fields, such as: sludge dehydration, soft foundation treatment, contaminated soil remediation, mud and water co-control, saline-alkali land control, rare earth green mining, etc.

[0003] For special soils such as mud ponds, tidal flats, and river channels, electroosmosis is an effective dehydration method because the soil particles are small and the permeability coefficient is low, making it difficult for pore water to seep out naturally. Electroosmosis dehydration technology is to place the water-containing soil under the action of an electric field. In a system where solid movement is restricted, the counterions in the diffusion layer move along the slip interface toward the electrode, while driving water molecules to move toward the cathode. Water is discharged from the cathode by suction or gravity drainage to achieve soil dehydration and consolidation.

[0004] Traditional vacuum preloading drainage often adopts the surface covering method. The vacuum film covering the soil surface provides a closed environment to achieve vacuum drainage. At the same time, the vacuum film also allows people and machinery to walk on the soft soil, which is convenient for construction operations such as buried electrodes. However, for soil containing a large amount of debris (stones, branches, etc.), the vacuum film covering the soil surface is easily scratched by debris, affecting the airtightness and thus the effect of vacuum drainage. On the other hand, if the soil is too soft, it will be difficult for people and machinery to walk on the soil surface, which will bring difficulties to large-scale construction operations. Summary of the invention

[0005] In view of the shortcomings of the surface coating method used for vacuum preloading drainage, the present application provides a method and device for soil electroosmosis dehydration.

[0006] The present application provides a method for soil electroosmosis dehydration using the following technical solution: A method for electroosmotic dehydration of soil, comprising the following steps: Device preparation: Use construction machinery to bury several perforated conductive pipes in the area to be consolidated on the shore, install liquid level gauges at two different depths in each perforated conductive pipe; insert a drainage pipe into each perforated conductive pipe, install a control valve on each drainage pipe, and connect the water outlet of all drainage pipes to a vacuum pump; connect the anode and cathode of the power supply to the corresponding perforated conductive pipes respectively; Electroosmotic dehydration: When power is turned on, the control valve of the drainage pipe in the anode perforated conductive tube is closed, and the control valve of the drainage pipe in the cathode perforated conductive tube controls the opening and closing state according to the water level in the cathode perforated conductive tube. The vacuum pump drains the accumulated water in the cathode perforated conductive tube until the soil in this area is consolidated.

[0007] Furthermore, after the consolidation of the area near the shore is completed, the consolidated area is used as the bearing foundation for the construction machinery, and the device preparation and electroosmosis dehydration steps are repeated in the area to be consolidated, gradually advancing towards the center of the area to be consolidated until the entire area is consolidated.

[0008] For soft soil that is difficult to support construction machinery, this application adopts a push-type construction method. First, the shore is used as the bearing foundation for the construction machinery, and perforated conductive pipes are buried in the area to be consolidated near the shore. After the area near the shore is consolidated, the area that has been consolidated is used as the bearing foundation for the construction machinery, and gradually pushed forward to the center of the area to be consolidated, and the device preparation and electroosmotic dehydration are carried out in sequence until the entire area is consolidated. This helps to improve the problem of difficulty in consolidation construction of large-scale soft soil.

[0009] The present application adopts a perforated conductive tube and a drainage pipe in conjunction with a vacuum pump to replace the surface coating in the traditional vacuum pre-pressure drainage. There is no problem of the vacuum film being scratched by debris and affecting the airtightness, thereby ensuring the effect of vacuum drainage.

[0010] Furthermore, the electroosmotic dehydration step also includes: when the water level in the cathode perforated conductive tube is higher than a first design water level, the drain pipe control valve in the perforated conductive tube is opened; when the water level in the cathode perforated conductive tube is not higher than a second design water level, the drain pipe control valve in the perforated conductive tube is closed; the first design water level is higher than the second design water level.

[0011] The present application only sets up one vacuum pump, and controls the pumping state of the corresponding perforated conductive tube by opening and closing the control valve on each drainage pipe; compared with connecting a vacuum pump to each drainage pipe, the present application simplifies the equipment and control method, and is conducive to saving electricity.

[0012] Since the water in the soil flows to the cathode during the electrification process, the control valve of the drainage pipe in the anode perforated conductive pipe needs to be kept closed to maintain the vacuum degree of the entire drainage pipeline.

[0013] When the water level in the cathode perforated conductive tube is higher than the first design water level, the drain pipe control valve in the perforated conductive tube is opened, so that the accumulated water in the perforated conductive tube can be pumped out in time.

[0014] When the water level in the cathode perforated conductive tube is not higher than the second design water level (the second design water level is lower than the first design water level), the drain pipe control valve in the perforated conductive tube is closed, thereby preventing the drain pipe from affecting the vacuum degree of the entire drainage pipeline due to air intake, which is beneficial to ensure drainage efficiency.

[0015] Furthermore, the device preparation step also includes: installing a check valve at the water inlet end of each drain pipe.

[0016] Furthermore, the electroosmotic dehydration step also includes: the opening and closing states of the check valve and the control valve remain consistent.

[0017] When the drain pipe is pumping water, the check valve and the control valve are opened at the same time. When the drain pipe is not pumping water, the control valve is closed to block the air connection between the vacuum pump and the drain pipe; at this time, the check valve is also closed to keep the drain pipe full of water, so that when the drain pipe is vacuumed again, the pumping effect will not be affected by air entering the drain pipe.

[0018] Furthermore, the electroosmotic dehydration step also includes: changing the connection state between the perforated conductive tube and the power supply according to the current change during the electroosmotic process, thereby adjusting the distance between the anode perforated conductive tube and the cathode perforated conductive tube.

[0019] As the electroosmotic dehydration proceeds, the resistance of the soil will gradually increase and the current will decrease. The present application adjusts the distance between the anode perforated conductive tube and the cathode perforated conductive tube according to the change in the current in the soil, that is, as the soil resistance increases, the distance between the anode perforated conductive tube and the cathode perforated conductive tube is gradually reduced, thereby keeping the electroosmosis process at a suitable current. Compared to the general method of using a voltage-regulating power supply for voltage regulation, the power supply of the present application is simple, and does not require a power supply with continuously adjustable voltage to achieve the effect of improving electroosmosis efficiency and reducing energy consumption.

[0020] The present application also provides a soil electroosmotic dehydration device, which is used to implement a soil electroosmotic dehydration method, and the device includes: power supply; A plurality of perforated conductive tubes are buried in the soil in an array and connected to the power source; liquid level meters are respectively installed at two different depths in the perforated conductive tubes; A plurality of drain pipes, corresponding to the perforated conductive pipes one by one, the water inlet ends of the drain pipes being located in the perforated conductive pipes, and control valves being installed on the drain pipes; Vacuum pump, connected to the outlet end of all drain pipes.

[0021] Furthermore, a check valve is installed at the water inlet end of the drain pipe.

[0022] Furthermore, it also includes a controller for controlling the opening and closing states of the corresponding control valve and the check valve according to the water level in the perforated conductive tube.

[0023] Furthermore, a filter layer is provided on the inner wall of the perforated conductive tube.

[0024] In summary, the present application includes at least one of the following beneficial technical effects: 1. This application adopts a push-type construction method, which gradually advances the construction from the shore to the center of the area to be consolidated and conducts electroosmosis consolidation in sequence, which helps to improve the difficulty of large-scale soft soil consolidation construction; 2. This application uses a perforated conductive tube and a drainage pipe with a vacuum pump to replace the surface coating in the traditional vacuum preloading drainage, which is conducive to ensuring the effect of vacuum drainage and can realize automatic extraction and drainage; 3. By controlling the opening and closing status of the check valve and the control valve, the accumulated water in the perforated conductive pipe can be pumped out in time, while preventing the pumping effect from being affected by air intake in the drainage pipe; 4. As the electroosmotic dehydration proceeds, the distance between the anode perforated conductive tube and the cathode perforated conductive tube is adjusted to keep the electroosmotic process at a suitable current, thereby improving the electroosmotic efficiency and reducing energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the overall structure of a soil electroosmotic dehydration device according to an embodiment of the present application; Figure 2 Schematic diagram of the push-type construction method in Example 1 of the present application, wherein (a) is a schematic diagram of the initial stage of construction, and (b) is a schematic diagram of the later stage of construction; Figure 3 It is a schematic diagram of the connection method between the perforated conductive tube and the power supply in Example 2 of the present application.

[0026] Figure numerals: 1. perforated conductive tube; 2. drainage pipe; 3. vacuum pump; 4. control valve; 5. first liquid level gauge; 6. check valve; 7. filter layer; 8. shore; 9. connector; 10. second liquid level gauge. DETAILED DESCRIPTION

[0027] The following is combined with Figure 1-3 This application is described in further detail.

[0028] The present application embodiment discloses a device for electroosmotic dehydration of soil. Figure 1 The device for electroosmotic dehydration of soil includes a power source (not shown in the figure), a plurality of perforated conductive pipes 1, a plurality of drainage pipes 2, a vacuum pump 3 and a controller.

[0029] Reference Figure 1, multiple perforated conductive tubes 1 are buried in the soil in an array, and each perforated conductive tube 1 is connected to the anode or cathode of the power supply. The inner wall of the perforated conductive tube 1 is provided with a filter layer 7, which can be a geotextile, which can prevent the mud and sand in the soil from entering the perforated conductive tube 1 and causing the drainage pipe 2 to be blocked. If the filter layer 7 is set on the outer wall of the perforated conductive tube 1, the resistance between the perforated conductive tube 1 and the soil is very large, which affects the electroosmosis effect; therefore, the filter layer 7 needs to be set on the inner wall of the perforated conductive tube 1.

[0030] Reference Figure 1 A first liquid level gauge 5 is installed near the bottom of the perforated conductive tube 1 , and a second liquid level gauge 10 is installed near the top of the perforated conductive tube 1 . The first liquid level gauge 5 and the second liquid level gauge 10 are used to monitor the water level in the perforated conductive tube 1 .

[0031] Reference Figure 1 , multiple drain pipes 2 correspond to the perforated conductive pipes 1 one by one, the water inlet end of the drain pipe 2 is located near the bottom of the perforated conductive pipe 1 and lower than the position of the first liquid level gauge 5, and a control valve 4 is installed on the upper part of the drain pipe 2. A check valve 6 is installed at the water inlet end of the drain pipe 2, and the check valve 6 only allows the water in the drain pipe 2 to flow in one direction from bottom to top, so that the drain pipe 2 remains full of water. The vacuum pump 3 is connected to the water outlet end of all the drain pipes 2.

[0032] The first liquid level gauge 5 , the second liquid level gauge 10 , the control valve 4 and the check valve 6 are all connected to a controller, and the controller is used to control the opening and closing states of the corresponding control valve 4 and the check valve 6 according to the water level in the perforated conductive tube 1 .

[0033] The following is a specific example to illustrate a method for implementing electroosmotic dehydration of soil using the above-mentioned soil electroosmotic dehydration device.

[0034] Example 1 This embodiment provides a method for electroosmotic dehydration of soil, which is used for electroosmotic dehydration of extremely soft soil, and includes the following steps: Step 1: Device preparation: Reference Figure 2 In (a), 2-3 rows of perforated conductive tubes 1 are buried in the area to be consolidated near the shore 8 using a cantilever machine.

[0035] Reference Figure 1 , a filter layer 7 is laid on the inner wall of the perforated conductive tube 1, and a first liquid level gauge 5 and a second liquid level gauge 10 are installed in each perforated conductive tube 1. A drain pipe 2 is inserted into each perforated conductive tube 1, a control valve 4 is installed on the upper part of the drain pipe 2, a check valve 6 is installed on the water inlet end of the drain pipe 2, and the water outlet ends of all the drain pipes 2 are connected to a vacuum pump 3.

[0036] Reference Figure 1, the anode and cathode of the power supply are respectively connected to the corresponding perforated conductive tubes 1, so that the anode perforated conductive tubes 1 and the cathode perforated conductive tubes 1 are arranged alternately.

[0037] Step 2: Electroosmotic dehydration: When the power is turned on, the vacuum pump 3 is started, the control valve 4 of the drain pipe 2 in the anode perforated conductive tube 1 is closed, and the control valve 4 of the drain pipe 2 in the cathode perforated conductive tube 1 controls the opening and closing state according to the water level in the cathode perforated conductive tube 1, specifically including: When the water level in the cathode perforated conductive tube 1 is higher than the second liquid level gauge 10, the drain pipe 2 control valve 4 and the check valve 6 in the perforated conductive tube 1 are both opened; when the water level in the cathode perforated conductive tube 1 is not higher than the first liquid level gauge 5, the drain pipe 2 control valve 4 and the check valve 6 in the perforated conductive tube 1 are both closed.

[0038] The vacuum pump 3 pumps out the accumulated water in the cathode perforated conductive tube 1. As the electroosmosis proceeds, the current decreases exponentially with time (I=Ae -at +B, where I is the current, t is the power-on time, A is the coefficient, a is the time index, B is the current margin constant, and e is the natural constant). When the current drops to approach the constant B, the electrode conversion is performed (the perforated conductive tube originally connected to the cathode of the power supply is connected to the anode of the power supply, and the perforated conductive tube originally connected to the anode of the power supply is connected to the cathode of the power supply), and the power is continued.

[0039] After the polarity is switched, the current will increase and then decrease exponentially with time. After repeated electrode switching, when the current drops to near zero or a very small current margin, the soil consolidation in this area is completed.

[0040] Step 3: Promote construction: After the consolidation of the area near the shore 8 is completed, refer to Figure 2 In (b), the area to be consolidated is used as the bearing foundation for the construction machinery, a perforated conductive pipe 1 is buried in the area to be consolidated near the center of the site, and the steps of device preparation and electroosmotic dehydration are repeated, gradually advancing towards the center of the site until all areas are consolidated.

[0041] Example 2 This embodiment provides a method for electroosmotic dehydration of soil. The difference from the first embodiment is that the soil in the second embodiment has sufficient hardness to bear the construction machinery, so there is no need to perform push-type construction. The method in the second embodiment includes the following steps: Step 1: Device preparation: A cantilever machine is used to bury the perforated conductive tubes 1 in an array in the area to be consolidated, and a filter layer 7 is laid on the inner wall of the perforated conductive tubes 1 . A first liquid level meter 5 and a second liquid level meter 10 are placed in each perforated conductive tube 1 .

[0042] A drain pipe 2 is inserted into each perforated conductive tube 1 , a control valve 4 is installed on the upper portion of the drain pipe 2 , a check valve 6 is installed at the water inlet end of the drain pipe 2 , and the water outlet ends of all the drain pipes 2 are connected to a vacuum pump 3 .

[0043] Reference Figure 3 A plurality of perforated conductive tubes 1 in the same row are connected by wires, and a connector 9 is connected between the wires and the power supply to control the connection or disconnection between the perforated conductive tubes 1 in the row and the anode / cathode of the power supply.

[0044] Step 2: Electroosmotic dehydration: When the power is turned on, the vacuum pump 3 is started, the control valve 4 of the drain pipe 2 in the anode perforated conductive tube 1 is closed, and the control valve 4 of the drain pipe 2 in the cathode perforated conductive tube 1 controls the opening and closing state according to the water level in the cathode perforated conductive tube 1, specifically including: When the water level in the cathode perforated conductive tube 1 is higher than the second liquid level gauge 10, the drain pipe 2 control valve 4 and the check valve 6 in the perforated conductive tube 1 are both opened; when the water level in the cathode perforated conductive tube 1 is not higher than the first liquid level gauge 5, the drain pipe 2 control valve 4 and the check valve 6 in the perforated conductive tube 1 are both closed.

[0045] The vacuum pump 3 pumps out the accumulated water in the cathode perforated conductive tube 1 until the soil in the area is consolidated.

[0046] As the electroosmotic dehydration proceeds, the resistance of the soil will gradually increase and the current will decrease. In order to ensure that the electroosmotic process is always carried out at an appropriate current, it is necessary to change the connection state of the perforated conductive tube 1 and the power supply as the soil current decreases, so that the distance between the anode perforated conductive tube 1 and the cathode perforated conductive tube 1 gradually decreases. The following uses a specific example to illustrate the adjustment method: Step a: Figure 3 As shown, a total of five rows of perforated conductive tubes 1 numbered (1) to (5) are buried in the area to be consolidated. A plurality of perforated conductive tubes 1 in each row are connected in series by wires to a power source, and a connector 9 is used to control the connection or disconnection of the row of perforated conductive tubes 1 with the anode / cathode of the power source.

[0047] Step b: At the beginning of power-on, the distance between the anode perforated conductive tube 1 and the cathode perforated conductive tube 1 is set to be medium, for example, a row of perforated conductive tubes 1 numbered (1) is connected to the anode of the power supply, and a row of perforated conductive tubes 1 numbered (3) is connected to the cathode of the power supply, and all other connectors 9 are disconnected, and then power is turned on. At this time, the distance between the anode perforated conductive tube 1 and the cathode perforated conductive tube 1 is adjusted according to the read current, as follows: If the current is greater than the set current upper limit (such as 60A), the spacing between the anode perforated conductive tube 1 and the cathode perforated conductive tube 1 is increased, for example, a column of perforated conductive tubes 1 numbered (1) is connected to the anode of the power supply, and a column of perforated conductive tubes 1 numbered (4) is connected to the cathode of the power supply, and all other connectors 9 are disconnected.

[0048] If the current is not greater than the set current upper limit (such as 60A), determine whether the current is less than the set current lower limit (such as 50A): if the current is less than the set current lower limit, reduce the spacing between the anode perforated conductive tube 1 and the cathode perforated conductive tube 1, for example, connect a row of perforated conductive tubes 1 numbered (1) to the anode of the power supply, connect a row of perforated conductive tubes 1 numbered (2) to the cathode of the power supply, and disconnect all other connectors 9; if the current is not less than the set current lower limit, maintain the current spacing ((1) is the anode, (3) is the cathode) to work.

[0049] Step c: As electroosmosis proceeds, the current decreases exponentially with time (I = Ae -at +B, where I is the current, t is the power-on time, A is the coefficient, a is the time index, B is the current margin constant, and e is the natural constant). When the current drops to a value close to constant B, the polarity of the perforated conductive tube 1 is changed, for example, a row of perforated conductive tubes 1 numbered (1) is connected to the cathode of the power supply, and a row of perforated conductive tubes 1 numbered (3) is connected to the anode of the power supply. The purpose of changing the polarity is to make the original cathode dry area wet, so as to reduce the resistance, increase the effective electric field strength of the soil, and improve the electroosmosis efficiency.

[0050] Step d: After the polarity is switched, the current will increase and then decrease exponentially with time. After repeated electrode switching, when the current drops to near zero or a very small current margin, the spacing between the anode perforated conductive tube 1 and the cathode perforated conductive tube 1 is reduced, for example, a column of perforated conductive tubes 1 numbered (1) is connected to the anode of the power supply, a column of perforated conductive tubes 1 numbered (2) is connected to the cathode of the power supply, and all other connectors 9 are disconnected; or a column of perforated conductive tubes 1 numbered (2) is connected to the anode of the power supply, and a column of perforated conductive tubes 1 numbered (3) is connected to the cathode of the power supply.

[0051] Step e: Repeat steps bd until all areas are consolidated.

[0052] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A method for electroosmotic dehydration of soil, characterized in that: The following steps are involved: Device preparation: Use construction machinery to bury several perforated conductive pipes in the area to be consolidated on the shore, install liquid level gauges at two different depths in each perforated conductive pipe; insert a drainage pipe into each perforated conductive pipe, install a control valve on each drainage pipe, and connect the water outlet of all drainage pipes to a vacuum pump; connect the anode and cathode of the power supply to the corresponding perforated conductive pipes respectively; Electroosmotic dehydration: When power is turned on, the control valve of the drainage pipe in the anode perforated conductive tube is closed, and the control valve of the drainage pipe in the cathode perforated conductive tube controls the opening and closing state according to the water level in the cathode perforated conductive tube. The vacuum pump drains the accumulated water in the cathode perforated conductive tube until the soil in this area is consolidated.

2. The method for electroosmotic dehydration of soil according to claim 1, characterized in that: The following steps are also included: After the area near the shore is consolidated, the consolidated area is used as the bearing foundation for the construction machinery, and the device preparation and electroosmosis dehydration steps are repeated in the area to be consolidated, gradually advancing towards the center of the area to be consolidated until the entire area is consolidated.

3. The method for electroosmotic dehydration of soil according to claim 1, characterized in that: The electroosmotic dehydration step also includes: when the water level in the cathode perforated conductive tube is higher than the first design water level, the drain pipe control valve in the perforated conductive tube is opened; when the water level in the cathode perforated conductive tube is not higher than the second design water level, the drain pipe control valve in the perforated conductive tube is closed; the first design water level is higher than the second design water level.

4. The method for electroosmotic dehydration of soil according to claim 3, characterized in that: The device preparation step also includes: installing a check valve at the water inlet end of each drain pipe.

5. The method for electroosmotic dehydration of soil according to claim 4, characterized in that: The electroosmotic dehydration step also includes: the opening and closing states of the check valve and the control valve remain consistent.

6. The method for electroosmotic dehydration of soil according to claim 1, characterized in that: The electroosmotic dehydration step also includes: changing the connection state between the perforated conductive tube and the power supply according to the current change during the electroosmotic process, thereby adjusting the distance between the anode perforated conductive tube and the cathode perforated conductive tube.

7. A soil electroosmotic dehydration device, used to implement the soil electroosmotic dehydration method according to any one of claims 1 to 6, characterized in that: include: power supply; A plurality of perforated conductive tubes are buried in the soil in an array and connected to the power source; Liquid level gauges are installed at two different depths in the perforated conductive tube; A plurality of drain pipes, corresponding to the perforated conductive pipes one by one, the water inlet ends of the drain pipes being located in the perforated conductive pipes, and control valves being installed on the drain pipes; Vacuum pump, connected to the outlet end of all drain pipes.

8. The device for electroosmotic dehydration of soil according to claim 7, characterized in that: A check valve is installed at the water inlet end of the drain pipe.

9. The device for electroosmotic dehydration of soil according to claim 8, characterized in that: It also includes a controller for controlling the opening and closing states of the corresponding control valve and the check valve according to the water level in the perforated conductive pipe.

10. The device for electroosmotic dehydration of soil according to claim 7, characterized in that: The inner wall of the perforated conductive tube is provided with a filter layer.

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