Gas-water pressure balance experimental device and experimental method

Abstract

The invention provides an air-water pressure balance experiment device and an experiment method. The air-water pressure balance experiment device comprises a cylinder body, a water pressure sensor, a water injection device and an air inflation device. In the experiment process, a soil sample can be added into the cylinder, a water source is input into the cylinder through the water injection device, so that the water source is saturated in the soil sample, then the air inflation device inflates air into the cylinder through the air injection ring, the soil sample can be filled with air along with the increase of the pressure of the inflated air, and the water source is filled into the cylinder through the air injection ring. Whether an inflation mode can play an effective role in cutting off a water source is judged by monitoring whether the water source is still discharged from the drainage pipe, the height of air in the soil sample rises upwards along with the increase of air pressure, and when the air spreads to the corresponding water pressure sensor, the pressure value of the water pressure sensor is increased along with the increase of the air. Therefore, the spreading depth of the air and the corresponding pressure value under the corresponding soil sample can be obtained, and data support is provided for later foundation pit water seepage prevention.

Description

Technical Field

[0001] This invention belongs to the field of gas-water pressure experiment technology, specifically relating to a gas-water pressure balance experimental device and experimental method. Background Technology

[0002] Dewatering of foundation pits typically requires sealing the perimeter of the pit to prevent external water from seeping in, which increases drainage costs later. Currently, the common method for preventing water seepage inside the pit is using a water-stop curtain, which is costly and inefficient. To improve construction efficiency and reduce costs during foundation pit dewatering, a gas-formed water-stop curtain can be used to prevent water from seeping into the pit, thereby reducing on-site construction costs.

[0003] When using gas as a waterproof barrier, the gas pressure and delivery volume need to be adjusted according to the actual soil conditions on site. Excessive gas pressure can easily cause the soil layer to crack, resulting in serious gas leakage and even failure of waterproofing performance. Conversely, insufficient gas pressure will prevent the formation of a stable waterproof barrier, allowing water to seep into the foundation pit. Currently, it is impossible to effectively determine the various parameters of the gas used before construction, thus affecting the subsequent construction results. Summary of the Invention

[0004] This invention provides a gas-water pressure balance experimental device and method, which aims to solve the problem that the parameters of gas-sealed water curtains are difficult to determine in the prior art, thus affecting the construction effect.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is: to provide an experimental apparatus for gas-water pressure balance, comprising: The cylinder is arranged vertically, with an overflow pipe at the top and a drain pipe at the bottom, and an inlet hole at the bottom. An air injection ring is installed in the middle of the cylinder. Air outlets are provided at both the upper and lower ends of the air injection ring. The axis of the air outlets is coaxial with the air injection ring. An air inlet is also provided on the air injection ring, which communicates with the air outlets. Multiple water pressure sensors are arranged vertically on the cylinder to monitor the water pressure inside the cylinder. The positions of the multiple water pressure sensors on the cylinder are symmetrically arranged vertically with the air injection ring as the center. A water injection device, wherein the water outlet of the water injection device is located at the top of the cylinder, is used to continuously input water into the cylinder; An inflation device is provided, wherein the air outlet of the inflation device is connected to the air inlet on the air injection ring, and a flow detector is provided on the air outlet of the inflation device.

[0006] In one possible implementation, a sealing plate is sealed to the bottom of the cylinder, the water inlet is located on the sealing plate, and an annular groove is recessed at the top of the sealing plate, with the drain pipe communicating with the bottom of the annular groove.

[0007] In one possible implementation, the cylinder includes an upper cylinder and a lower cylinder, both of which are detachably and sealingly connected to the gas injection ring.

[0008] In one possible implementation, a horizontal pipe is connected to the top of the cylinder, the middle of the overflow pipe and the middle of the drain pipe are both connected to the horizontal pipe, and a control valve is provided on the drain pipe to control the connection state between the drain pipe and the horizontal pipe. A sealing plug is provided in the middle of the horizontal pipe to block the connection between the drain pipe and the overflow pipe.

[0009] The solution shown in this application, compared with the prior art, incorporates a cylindrical body with a drainage pipe connected to the interior of the body on its bottom side wall, an overflow pipe at the top, and a water inlet at the center of the bottom. During the experiment, soil samples are added to the body, and water is injected into the body through a water injection device to saturate the soil sample. An air-inflating device then pressurizes the body with air through an air-inflating ring. As the air pressure increases, air fills the soil sample. By monitoring whether water continues to drain from the drainage pipe, the effectiveness of the air-inflating method in is determined. As the air pressure increases, the air inside the soil sample rises. When the air reaches the corresponding water pressure sensor, the pressure reading increases, allowing for the determination of the air spread depth and corresponding pressure value for the soil sample. This provides data support for subsequent foundation pit seepage prevention.

[0010] In conjunction with the first aspect, this application also provides a gas-water pressure balance experimental method, employing the aforementioned gas-water pressure balance experimental apparatus, comprising the following steps: S1: Sample loading, filling the inside of the cylinder with soil sample material; S2: Water saturation: Water is injected into the cylinder through the water inlet at the bottom of the cylinder until the water flow rate from the overflow pipe is equal to the water flow rate from the water inlet. S3: Saturation test, water is continuously injected from the top of the cylinder into the cylinder through the water injection device, and the water output from the drain pipe at the bottom of the cylinder is monitored; S4: Inflation test. After the water flow from the drain pipe stabilizes, open the drain pipe at the bottom of the cylinder and reduce the opening. The inflation device inflates the cylinder with air through the air inlet on the air ring. Adjust the air pressure and monitor the drainage flow of the drain pipe at the bottom of the cylinder until no more water is discharged from the drain pipe. Record the air pressure value at this time and define it as the first pressure.

[0011] In one possible implementation, before step 2 and before step 4, the water inlet at the bottom of the cylinder is closed, and water is injected from the top of the cylinder. After the water flow rate from the drain pipe (12) at the bottom of the cylinder stabilizes, an air-filling test is performed to detect whether the water source is effectively saturated inside the soil sample, laying a good foundation for the subsequent gas volume spread detection.

[0012] In one possible implementation, after step 4 is completed, the drain pipe is closed, and the air intake pressure on the air injection ring is gradually increased. When the value of the water pressure sensor above the air injection ring fluctuates, the air intake pressure at this time is recorded as the second pressure. Then, the drain pipe is opened and connected to the horizontal pipe, and water is refilled to saturation. Then, air is refilled and the air intake pressure on the air injection ring is gradually increased. When the value of the water pressure sensor below the air injection ring fluctuates, the air intake pressure at this time is recorded as the third pressure.

[0013] In one possible implementation, after the first and second pressures are detected, steps 2 and 3 are repeated. The height of the drain pipe outlet is adjusted to match that of the overflow pipe, and the water injection device is turned off. Gas is injected into the cylinder through the air inflation device until the air inlet pressure is higher than the first pressure but lower than the second and third pressures. After no water flows out of the overflow pipe, the air pressure is increased to the second or third pressure, and the flow rate of the overflow pipe and the amount of water flowing out of the drain pipe are monitored.

[0014] In one possible implementation, during the inflation test, the inflation pressure is increased from a static value to a stable value and held for a certain period of time. Then, the water flow rate at the drain pipe is measured and the value is recorded. Then, the pressure is increased to a stable value again and held for a certain period of time. Then, the water flow rate at the drain pipe is measured and the value is recorded. The above steps are repeated until no more water is discharged from the drain pipe.

[0015] In one possible implementation, during the inflation process, when no water is discharged from the drain pipe at the bottom of the cylinder, the pressure value at the water pressure sensor is observed during the dwell time after the pressure value increases. When the pressure value of the corresponding water pressure sensor changes, the inflation pressure value and the position of the corresponding water pressure sensor are recorded.

[0016] The solution described in this application, compared with the prior art, involves filling and compacting a soil sample corresponding to the geological conditions inside a cylinder during the experiment. The top of the soil sample is positioned below the overflow pipe at the top of the cylinder. Water is then continuously injected into the cylinder until the soil sample reaches saturation. The saturation state of the soil sample is detected by monitoring the outflow from the drain pipe at the bottom of the cylinder. Once the outflow from the drain pipe at the bottom of the cylinder reaches a stable state within a certain period, the soil sample is considered fully filled and saturated. After the soil sample is saturated, the opening of the drainage pipe is reduced, and high-pressure gas is injected into the cylinder through the air injection ring via the air ventilation device. Air begins to fill the gaps in the soil sample from the bottom middle of the cylinder. As the air pressure increases, the air filling height also increases. When the air fills the cross-section, water cannot flow through the soil sample to the drainage pipe, thus blocking the water flow. This allows us to determine whether water leakage can be blocked by gas under the same soil sample conditions. When the gas pressure is at the first level, the length of the gas-covered cross-section is equal to the inner diameter of the cylinder, providing reliable experimental data for later construction. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the gas-water pressure balance experimental device provided in an embodiment of the present invention; Figure 2 A schematic diagram of the installation structure of the sealing disc provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of the installation structure of the pressure flange provided in an embodiment of the present invention; Figure 4 A flowchart of the gas-water pressure balance experimental method provided in an embodiment of the present invention.

[0018] Explanation of reference numerals in the attached figures: 1. Cylinder body; 14. Upper cylinder column; 15. Lower cylinder column; 11. Overflow pipe; 111. Horizontal pipe; 112. Sealing plug; 12. Drain pipe; 13. Water inlet; 2. Water pressure sensor; 3. Water injection device; 4. Air inflation device; 5. Sealing plate; 6. Pressurizing flange; 7. Air injection ring; 8. Pressure stabilizing tank. Detailed Implementation

[0019] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0020] Please refer to the following: Figures 1 to 3The gas-water pressure balance experimental device provided by the present invention will now be described. The gas-water pressure balance experimental device includes a cylinder 1, an air injection ring 7, water pressure sensors 2, a water injection device 3, and an air filling device 4. The cylinder 1 is arranged vertically, with an overflow pipe 11 at the top and a drain pipe 12 at the bottom. The bottom of the cylinder 1 also has a water inlet 13. The air injection ring 7 is installed in the middle of the cylinder 1, and air outlets are provided at both its upper and lower ends. The axis of the air outlets is coaxial with that of the air injection ring 7. The air injection ring 7 also has an air inlet communicating with the air outlets. Multiple water pressure sensors 2 are used, and the multiple water pressure sensors 2 are arranged along... The multiple water pressure sensors 2 are arranged vertically on the cylinder 1 to monitor the water pressure inside the cylinder 1. The positions of the multiple water pressure sensors 2 on the cylinder 1 are symmetrically arranged vertically with the air injection ring 7 as the center. The water outlet of the water injection device 3 is located at the top of the cylinder 1 and is used to continuously input water into the cylinder 1. The air outlet of the air inflation device 4 is connected to the air inlet on the air injection ring 7, and a flow detector is provided on the air outlet of the air inflation device 4.

[0021] Compared with the prior art, the gas-water pressure balance experimental device provided in this embodiment is provided with a cylinder 1, which is a cylindrical structure. A drain pipe 12 communicating with the inside of the cylinder 1 is provided on the bottom side wall of the cylinder 1, an overflow pipe 11 is provided on the top of the cylinder 1, and a water inlet hole 13 is provided at the center of the bottom of the cylinder 1. During the experiment, soil samples can be added to the inside of the cylinder 1, and water can be introduced into the cylinder 1 through the water injection device 3 to saturate the soil sample. Then, the air inflation device 4 pressurizes air into the inside of the cylinder 1 through the air injection ring 7. As the pressure of the pressurized air increases, air can fill the soil sample. By monitoring whether water is still being discharged from the drainage pipe 12, it can be determined whether the air inflation method can effectively isolate the water source. As the air pressure increases, the air height inside the soil sample rises. When the air spreads to the corresponding water pressure sensor 2, the pressure value of the water pressure sensor 2 will increase accordingly. Thus, the spread depth of the air and the corresponding pressure value under the corresponding soil sample can be obtained, providing data support for the subsequent seepage prevention of the foundation pit.

[0022] Specifically, in this embodiment, the cylinder 1 is made of transparent plexiglass, so that the experimenter can record the range of gas influence by observing the color change of the soil sample.

[0023] Specifically, in this embodiment, an overflow pipe 11 is provided at the top of the cylinder 1. When the water injection device 3 adds water to the inside of the cylinder 1, the water seeps into the soil sample on the one hand, and keeps the liquid level inside the cylinder 1 at a stable height on the other hand, so that the water pressure inside the soil sample is stable and avoids errors in experimental data caused by changes in water pressure.

[0024] Preferably, in this embodiment, when filling the inside of the cylinder 1 with soil sample, a layer of crushed stone needs to be filled at the bottom of the cylinder 1 and the top of the soil sample to reduce the soil sample from flowing out of the drain pipe 12 or the overflow pipe 11. At the same time, the top surface of the crushed stone layer at the bottom of the cylinder 1 is higher than the height of the drain pipe 12.

[0025] Specifically, in this embodiment, the inflation device 4 includes an air compressor and a pressure stabilizing tank 8 connected to the air compressor. The output end of the pressure stabilizing tank 8 is connected to the air inlet of the air injection ring 7. By installing a flow detection device at the air delivery end of the inflation device 4, the output gas volume of the inflation device 4 can be monitored, providing experimental data for the subsequent gas usage and the subsequent calculation of the permeability of the soil sample.

[0026] Specifically, in this embodiment, the water injection device 3 uses a Marshall bottle or a water bucket to deliver water to the inside of the cylinder 1 through a water pipe. The air filling device 4 uses an air compressor, and a pressure stabilizing tank 8 is connected to the output end of the air compressor. A pressure regulating valve for adjusting the output air pressure is provided at the output end of the pressure stabilizing tank 8.

[0027] In some embodiments, the cylinder 1 may be adopted as follows: Figure 1 , Figure 2 The structure shown. See also... Figure 1 , Figure 2 The bottom of the cylindrical body 1 is sealed with a sealing disc 5. The water inlet 13 is located on the sealing disc 5, and the top of the sealing disc 5 is recessed with an annular groove. The drain pipe 12 is connected to the bottom of the annular groove. The cylindrical body 1 is fitted onto the outside of the sealing disc 5, and the cylindrical body 1 is sealed to the outer ring of the sealing disc 5. An annular groove is provided on the top of the sealing disc 5, and the drain pipe 12 is connected to the bottom of the annular groove. The water inlet 13 is located on the sealing disc 5 and at the axial position of the sealing disc 5. During the saturation test, seepage water can stably flow into the annular groove and be discharged through the drain pipe 12.

[0028] Specifically, in this embodiment, a valve for controlling the drainage flow is installed on the drain pipe 12. During the initial inflation process, gas at an initial pressure is injected into the cylinder 1 through the air injection ring 7. The inflation pressure is stabilized by adjusting the opening of the valve on the drain pipe 12. Then, the change in the water source flowing out of the drain pipe 12 is observed over a certain period of time. If no water flows out of the drain pipe 12 within a certain period of time, it proves that the pressure of the gas can effectively block water seepage. If water is still discharged within a certain period of time, the gas pressure is increased by a certain value, and the above steps are repeated.

[0029] Specifically, in this embodiment, when there is no water source discharged from the drain pipe 12, the seepage phenomenon can be blocked by gas, the pressure value at this time is recorded, and after the drain pipe 12 is closed, the pressure is continued to be increased, and the subsequent gas infiltration depth and corresponding pressure value are measured, which can reduce the waste of gas flowing out of the drain pipe 12.

[0030] In some embodiments, the cylinder 1 may be adopted as follows: Figure 1 , Figure 2 The structure shown. See also... Figure 1 , Figure 2 The cylinder 1 includes an upper cylinder 14 and a lower cylinder 15, both of which are detachably and sealingly connected to the air injection ring 7. The cylinder 1 is generally divided into two parts: the upper cylinder 14 and the lower cylinder 15, which are connected by the air injection ring 7. When filling soil samples, soil samples can be filled into the lower cylinder 15 first, then the air injection ring 7 and the upper cylinder 14 can be installed, and finally, soil samples can be filled into the upper cylinder 14. This facilitates the initial soil sample filling.

[0031] Specifically, in this embodiment, a limiting ring for limiting the upper cylinder 14 and the lower cylinder 15 is provided in the middle of the gas injection ring 7, and multiple sealing rings are installed on the inner wall of the gas injection ring 7. When the upper cylinder 14 and the lower cylinder 15 are respectively installed inside the gas injection ring 7, the sealing rings abut against the outer walls of the upper cylinder 14 and the lower cylinder 15, thereby achieving a sealed connection between the gas injection ring 7 and the upper cylinder 14 and the lower cylinder 15. The structure is simple and facilitates the disassembly and connection between the cylinder 1 and the gas injection ring 7.

[0032] Specifically, in this embodiment, the water injection device 3 is provided with a branch that communicates with the water inlet 13 at the bottom of the cylinder 1. Before the air-filling experiment inside the cylinder 1, the water source inside the soil sample needs to be saturated to effectively simulate the working conditions at the construction site. However, by injecting water into the cylinder 1 from the top, the air inside the soil sample cannot be discharged in a timely and effective manner, resulting in a longer saturation time and a waste of water. Before the saturation test, water is first injected into the cylinder 1 through the water inlet 13 at the bottom of the cylinder 1, and the flow of the drain pipe 12 is closed. This allows the water source to move upward from the bottom of the cylinder 1. On the one hand, the water source can quickly and effectively fill the soil sample according to its own gravity, and on the other hand, the air inside the soil sample can be quickly discharged from the top of the cylinder 1, which can effectively accelerate the saturation state of the water source inside the soil sample.

[0033] Specifically, in this embodiment, after the water source flows out from the overflow pipe 11 at the top of the cylinder 1, the water injection device 3 is used to add water from the top of the cylinder 1. Then, the drain pipe 12 at the bottom of the cylinder 1 is opened, and the saturation of the water source inside the soil sample is verified by detecting the amount of water discharged from the drain pipe 12 over a certain period of time. When the amount of water discharged from the drain pipe 12 stabilizes, the internal gaps of the soil sample inside the cylinder 1 can be filled with water, reaching a water saturation state.

[0034] In some embodiments, the cylinder 11 may be adopted as follows: Figure 1 , Figure 3 The structure shown. See also... Figure 1 , Figure 3 The top of the cylinder 1 can also be detachably fitted with a pressing flange 6, which has a pressing part extending into the interior of the cylinder 1. The cylinder 1 is fixedly mounted on a support frame, on which multiple support rods are also fixedly mounted. These support rods are arranged vertically, and the pressing flange 6 is slidably mounted on the support rods. A pressing part is located at the bottom of the pressing flange 6, which slides into the interior of the cylinder 1 to press against the top of the soil sample. This prevents the soil sample from shifting upwards and affecting data acquisition during bottom aeration or water addition.

[0035] Preferably, in this embodiment, the pressing part is made of wood and is fixedly installed at the bottom of the pressing flange 6.

[0036] Specifically, in this embodiment, a pressure plate is slidably arranged on the support rod. The bottom end of the pressure plate abuts against the top end of the upper cylinder 1 and is limited by bolts threaded to the support rod. Through the design of the pressure plate, the fixed connection between the air injection ring 7 and the upper cylinder 1 and the lower cylinder 1 can also be realized. By pressing the upper cylinder 1 with the pressure plate, the upper cylinder 1 and the lower cylinder 1 can be stably inserted into the air injection ring 7.

[0037] In some embodiments, the drain pipe 12 may be as follows: Figure 2 The structure shown. See also Figure 2 A horizontal pipe 111 is connected to the top of the cylinder 1. The middle parts of the overflow pipe 11 and the middle parts of the drain pipe 12 are both connected to the horizontal pipe 111. A control valve is provided on the drain pipe 12 to control the connection between the drain pipe 12 and the horizontal pipe 111. A sealing plug 112 is provided in the middle of the horizontal pipe 111 to block the connection between the drain pipe 12 and the overflow pipe 11. Both the overflow pipe 11 and the drain pipe 12 are connected to the horizontal pipe 111. A valve is also installed at the outlet end of the drain pipe 12 to control the output state of the drain pipe 12. By closing the valve and opening the control valve, the water discharged from the drain pipe 12 can be transported to the horizontal pipe 111. In the initial stage of the experiment, the drain pipe 12 can be connected to the horizontal pipe 111. When the drain pipe 12 is opened, water located inside the lower cylinder 15 can be prevented from flowing out of the drain pipe 12. Meanwhile, the top of the drain pipe 12 is flush with the overflow pipe 11, thus simulating the pressure of water seeping into the cylinder 15 from the ground.

[0038] Specifically, in this embodiment, during the saturation test, the state of the drain pipe 12 is controlled to drain water from the bottom of the cylinder 1; during the first pressure test, the state of the drain pipe 12 is controlled to drain water from the bottom of the cylinder 1, and the opening is reduced to ensure internal pressure balance; when the third pressure is measured, the state of the drain pipe 12 is controlled to connect the drain pipe 12 to the horizontal and drain water from the horizontal pipe 111. During water saturation and the second pressure test, the drain pipe 12 is in a closed state. The state of the drain pipe 12 is adjusted by the valve and control valve on the drain pipe 12.

[0039] Specifically, in this embodiment, a vertical pipe connects the drain pipe 12 and the horizontal pipe 111, and a pressure stabilizing tank 8 is connected in the middle of the vertical pipe. The height of the pressure stabilizing tank 8 is higher than the height of the lower cylinder 15. The pressure stabilizing tank 8 can increase the liquid volume, thereby increasing the internal pressure of the lower cylinder 15. The pressure value inside the lower cylinder 15 can be adjusted through the pressure stabilizing tank 8. When calculating the third pressure, even after the gas blocks the upper cylinder 14 and the lower cylinder 15, a certain water pressure can still be ensured inside the lower cylinder 15. When the gas does not spread to the water pressure sensor 2 below the air injection ring 7, the value at the water pressure sensor 2 is the value under normal conditions. When the gas spreads to the corresponding water pressure sensor 2 below the water injection ring, the value at the water pressure sensor 2 is the gas pressure value inside the lower cylinder 15. That is, the relationship between the depth of gas pressure spreading downward and the change value of gas pressure under stable overflow pressure can be simulated.

[0040] In conjunction with the first aspect, this application also provides a gas-water pressure balance experimental method, see [link to relevant documentation]. Figure 4The above-mentioned gas-water pressure balance experimental apparatus also includes the following steps: S1: Sample loading, filling the inside of cylinder 1 with soil sample material; S2: When the water is saturated, water is injected into the inside of the cylinder 1 through the water inlet 13 at the bottom of the cylinder 1 until the water flow rate of the overflow pipe 11 is equal to the water flow rate of the water inlet 13. S3: Saturation test, water is continuously injected into the cylinder 1 from the top through the water injection device 3, and the water output of the drain pipe 12 at the bottom of the cylinder 1 is monitored. S4: Inflation test. After the water flow from the drain pipe 12 stabilizes, open the water outlet end of the drain pipe 12 at the bottom of the cylinder 1 and reduce the opening. The inflation device 4 inflates the cylinder 1 with air pressure through the air inlet on the air ring 7. Adjust the air pressure and monitor the drainage flow of the drain pipe 12 at the bottom of the cylinder 1 until no more water is discharged from the drain pipe 12. Record the air pressure value at this time and define it as the first pressure.

[0041] The solution described in this application, compared with the prior art, involves filling the cylinder 1 with soil sample material corresponding to the geological conditions and compacting it during the experiment. The top of the soil sample is positioned below the overflow pipe 11 at the top of the cylinder 1. Water is then continuously injected into the cylinder 1 until the soil sample reaches a saturated state. The saturation state of the soil sample is detected by monitoring the outflow from the drain pipe 12 at the bottom of the cylinder 1. Once the outflow from the drain pipe 12 at the bottom of the cylinder 1 reaches a stable state within a certain period, the soil sample is considered fully filled and saturated. After the soil sample is saturated, the opening of the drainage pipe 12 is reduced, and high-pressure gas is injected into the cylinder 1 through the air injection ring 7 via the air ventilation device. Air begins to fill the gaps in the soil sample from the bottom middle of the cylinder 1. As the air pressure increases, the air filling height increases accordingly. When the air fills the cross-section, water cannot flow through the soil sample to the drainage pipe 12, thus blocking the water flow. This allows us to determine whether water leakage can be blocked by gas under the same soil sample conditions. When the gas pressure is at the first level, the length of the gas-covered cross-section is equal to the inner diameter of the cylinder 1, providing reliable experimental data for later construction.

[0042] Specifically, in this embodiment, during the sample loading step, the soil sample is mixed and proportioned according to the experimental objective. Then, the mixed soil sample is loaded into the cylinder 1 to a certain height and compacted. Then, more soil sample is added into the cylinder 1 and compacted again. The above steps are repeated to ensure the fullness of the soil sample added into the cylinder 1 and to ensure the accuracy of the experimental data.

[0043] In some embodiments, after the sample loading is completed, the following steps are also included: before step 2, water is injected through the water inlet 13 at the bottom of the cylinder 11 until water flows out of the overflow pipe 11. By connecting the liquid injection pipe to the outlet of the water injection device 33, water is injected into the cylinder 11 from the bottom through the water injection device 33, thereby improving the saturation efficiency and saturation effect of the water source inside the soil sample, and effectively expelling the gas inside the soil sample from the top of the soil sample.

[0044] In some embodiments, the inflation test includes increasing the inflation pressure from static to a stable pressure value and holding it for a certain period of time, then detecting and recording the water flow rate at the drain pipe 12, then increasing the stable pressure value again and holding it for a certain period of time, then detecting and recording the water flow rate at the drain pipe 12, and repeating the above steps until no more water is discharged from the drain pipe 12.

[0045] Specifically, after the soil sample is saturated with water, the outlet of the aeration device 4 is connected to the inlet of the aeration ring 7 for aeration. The aeration pressure is gradually increased from 0 kPa to 20 kPa, with a pause of 0.5-1 h at every 1 kPa. The discharge flow rate is observed and recorded. After the flow rate stops changing, the pressure is increased by 1 kPa. The above steps are repeated. When no water is discharged from the drainage pipe 12, the pressure value is recorded. This verifies that the aeration method can effectively prevent water leakage from the soil sample.

[0046] In some embodiments, before step 4, the water inlet 13 at the bottom of the cylinder 1 is closed, and water is injected from the top of the cylinder 1. The inflation test is conducted only after the water flow from the drain pipe 12 at the bottom of the cylinder 1 has stabilized. During the inflation test, water is always injected from the top of the cylinder 1 to simulate the actual seepage pressure and seepage conditions on site. When the inflation pressure reaches the first pressure, the gas can block the water source from flowing from the upper cylinder 14 to the lower cylinder 15. Therefore, the effectiveness of the blocking effect can be determined by observing the flow state of the drain pipe 12.

[0047] Specifically, in this embodiment, after the gas is pressurized, it is held for a period of time before the state of the drain pipe 12 is monitored. When only gas is discharged from the drain pipe 12, the pressure at this time can be determined to be the first pressure. At the same time, through the design of the upper cylinder 14 and the lower cylinder 15, the water inside the lower cylinder 15 can be quickly discharged by gas pressure during the first pressure test.

[0048] In some embodiments, after step 4 is completed, the drain pipe 12 is closed, and the air intake pressure on the air injection ring 7 is gradually increased. When the value of the water pressure sensor 2 above the air injection ring 7 fluctuates, the air intake pressure at this time is recorded as the second pressure. Then, the drain pipe 12 is opened and connected to the horizontal pipe 111, and water is refilled to saturation. Then, air is refilled, and the air intake pressure on the air injection ring 7 is gradually increased. When the value of the water pressure sensor 2 below the air injection ring 7 fluctuates, the air intake pressure at this time is recorded as the third pressure. When the drain pipe 12 is closed, the area below the air injection ring 7 is in a closed state. At this time, the gas will flow upwards from the air injection ring 7. Until the pressure is increased to the point where the gas flows to the water pressure sensor 2, the pressure value of the water pressure sensor 2 fluctuates. At this time, the air intake pressure is the second pressure. Under the second pressure state, the range of gas coverage is the height difference between the position of the air outlet on the air injection ring 7 and the corresponding water pressure sensor 2.

[0049] Specifically, in this embodiment, after the second pressure test is completed, the system is refilled with water to saturate the system, and then refilled with air. During refilling, the initial pressure is directly adjusted to the first pressure. At this time, the drain pipe 12 is connected to the horizontal pipe 111, and the water pressure inside the section connecting the horizontal pipe 111 and the drain pipe 12 simulates the actual situation on site. When the air pressure increases until the gas flows to the water pressure sensor 2 below the air injection ring 7, the value detected by the water pressure sensor 2 changes, and this is the third pressure value. By comparing the second pressure value and the third pressure value, it can be determined whether the upward and downward extension lengths of the gas are consistent when there is a certain pressure below the air injection ring 7. Furthermore, the length of the gas spreading downwards is obtained at the third pressure value, and the length of the gas spreading upwards is obtained at the second pressure value.

[0050] Specifically, in this embodiment, during the inflation process, the drain pipe 12 at the bottom of the cylinder 1 is closed after no water is discharged. During the time interval following the increase in pressure, the pressure change at the water pressure sensor 2 above the air injection ring 7 is observed. When the pressure value of the corresponding water pressure sensor 2 changes, the inflation pressure and the position of the corresponding water pressure sensor 2 are recorded. After the experimental inflation method effectively blocks water seepage, the range of gas influence is recorded by observing the change in soil sample color. After a period of time, the inflation pressure is further increased. As the pressure increases, the gas spreads upwards inside the cylinder 1 until it fills the water pressure sensor 2 above the air injection ring 7. A water pressure sensor is installed every 170mm on one side of the cylinder 1 to observe water pressure changes. When the monitoring point is affected by inflation, the pore water pressure sensor value will change. This allows for the acquisition of the gas influence range at the corresponding pressure value, providing a more intuitive and accurate assessment of the gas influence range.

[0051] Preferably, in this embodiment, the inflation test can test the feasibility of using gas as a water-stop curtain, and at the same time detect the influence range of gas under different pressures. Based on the recorded pressure values ​​and gas extension depth, the relationship between pressure and gas extension depth can be analyzed, providing effective data support for subsequent construction plans.

[0052] Specifically, in this embodiment, after no water is discharged from the drain pipe 12, the bottom drain pipe 12 is closed, the air injection ring 7 is connected to the air inflation device 4, the water level at the top of the cylinder 1 remains unchanged, the air inflation device 4 is opened, and the inflation pressure is gradually increased from 1 kPa. At each inflation pressure level, the pore water pressure sensor 2 collects data once every 10 seconds.

[0053] In some embodiments, after the first and second pressure tests are completed, steps 2 and 3 are repeated. The height of the outlet end of the drain pipe 12 is adjusted to be consistent with the overflow pipe 11, and the water injection device 3 is turned off. Gas is injected into the cylinder 1 through the air inflation device 4 until the air inlet pressure is higher than the first pressure but lower than the second and third pressures. After no water flows out of the overflow pipe 11, the air pressure is increased to the second or third pressure, and the flow rate of the overflow pipe 11 and the amount of water flowing out of the drain pipe 12 are monitored. After obtaining the second and third pressures, the water saturation and saturation tests are repeated, and the height of the outlet end of the drain pipe 12 is adjusted to be consistent with the overflow pipe 11, that is, the drain pipe 12 drains water through the horizontal pipe 111. First, water is injected into the cylinder 1 using the water injection device 3 so that both the drain pipe 12 and the overflow pipe 11 are in a state of water flowing out of the horizontal pipe 111. Inflation and pressurization are performed using an air-injection ring 7, raising the pressure to a level higher than the first pressure but lower than the second and third pressures. Water injection is then stopped. Once no water flows out of the horizontal pipe 111, the inflation pressure on the air-injection ring 7 is gradually increased again to the second or third pressure. The flow rate of water flowing out of the overflow pipe 11 and drain pipe 12 after the second pressure increase of the air-injection ring 7 is monitored. By calculating the flow rate, the volume of gas spreading above and below the air-injection ring 7 at the second or third pressure can be determined. Comparing this with the cross-section of the cylinder 1 and the spread length yields more accurate data.

[0054] Specifically, in this embodiment, before adjusting the gas pressure to the second or third pressure, the inlet pressure is first adjusted to be higher than the first pressure but lower than the second and third pressures. At this time, the gas can isolate the upper and lower sides of the injection ring 7. After the pressure is increased again, the drainage volume of the overflow pipe 11 is the same as the drainage volume of the upper cylinder 14 within a certain differential pressure range, and the drainage volume of the drain pipe 12 is the same as the drainage volume inside the lower cylinder 15 within the same differential pressure range. Thus, the volume change pattern of the upper and lower extensions of the injection ring 7 within a certain differential pressure range can be obtained. This application can test multiple data points and effectively simulate the range of gas extension under a certain pressure. It can also simulate the change pattern between gas pressure and water pressure at the later buried pipe location below the soil sample, thereby providing effective data support for subsequent construction.

[0055] Specifically, in this embodiment, the distance between the water pressure sensor 2 and the air outlet end of the air injection ring 7 is greater than the inner diameter of the cylinder 1.

[0056] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A gas-water pressure balance experimental apparatus, characterized in that, include: The cylinder (1) is arranged in a vertical direction. An overflow pipe (11) is provided at the top of the cylinder (1), a drain pipe (12) is provided at the bottom of the cylinder (1), and a water inlet (13) is also provided at the bottom of the cylinder (1). An air injection ring (7) is installed in the middle of the cylinder. Air outlets are provided at both the upper and lower ends of the air injection ring (7). The axis of the air outlet is coaxial with the air injection ring (7). An air inlet is also provided on the air injection ring (7) that communicates with the air outlet. Multiple water pressure sensors (2) are arranged vertically on the cylinder (1) to monitor the water pressure inside the cylinder (1). The positions of the multiple water pressure sensors (2) on the cylinder (1) are symmetrically arranged vertically with the air injection ring (7) as the center. Water injection device (3), the water outlet of the water injection device (3) is located at the top of the cylinder (1), and is used to continuously input water into the cylinder (1); An inflation device (4) is provided, wherein the air outlet of the inflation device (4) is connected to the air inlet on the air injection ring (7), and a flow detector is provided on the air outlet of the inflation device (4).

2. The gas-water pressure balance experimental apparatus as described in claim 1, characterized in that, The bottom of the cylinder (1) is sealed with a sealing plate (5), the water inlet (13) is located on the sealing plate (5), and the top of the sealing plate (5) is recessed with an annular groove. The drain pipe (12) is connected to the bottom of the annular groove.

3. The gas-water pressure balance experimental apparatus as described in claim 1, characterized in that, The cylinder (1) includes an upper cylinder (14) and a lower cylinder (15), both of which are detachably and sealingly connected to the air injection ring (7).

4. The gas-water pressure balance experimental apparatus as described in claim 1, characterized in that, A horizontal pipe (111) is connected to the top of the cylinder (1). The middle part of the overflow pipe (11) and the middle part of the drain pipe (12) are both connected to the horizontal pipe (111). A control valve is provided on the drain pipe (12) to control the connection between the drain pipe (12) and the horizontal pipe (111). A sealing plug (112) is provided in the middle of the horizontal pipe (111) to block the connection between the drain pipe (12) and the overflow pipe (11).

5. A method for gas-water pressure balance experiment, using the gas-water pressure balance experiment apparatus as described in any one of claims 1-4, characterized in that, Includes the following steps: S1: Sample loading, filling the inside of the cylinder (1) with soil sample material; S2: When the water is saturated, water is injected into the cylinder through the water inlet (13) at the bottom of the cylinder (1) until the water flow rate of the overflow pipe (11) is equal to the water flow rate of the inlet (13); S3: Saturation test, water is continuously injected from the top of the cylinder (1) into the cylinder (1) through the water injection device (3), and the water output of the drain pipe (12) at the bottom of the cylinder (1) is monitored; S4: Inflation test. After the water flow of the drain pipe (12) stabilizes, open the water outlet end of the drain pipe (12) at the bottom of the cylinder and reduce the opening. The inflation device (4) inflates the cylinder (1) with air pressure through the air inlet on the air ring (7). Adjust the air pressure and monitor the drainage flow of the drain pipe (12) at the bottom of the cylinder (1) until no more water is discharged from the drain pipe (12). Record the air pressure value at this time and define it as the first pressure.

6. The gas-water pressure balance experimental method as described in claim 5, characterized in that, Before proceeding to step 4, close the water inlet (13) at the bottom of the cylinder (1) and start filling the cylinder (1) with water from the top. After the water flow from the drain pipe (12) at the bottom of the cylinder (1) stabilizes, perform the air filling test.

7. The gas-water pressure balance experimental method as described in claim 5, characterized in that, After step 4 is completed, close the drain pipe (12) and gradually increase the air intake pressure on the air injection ring (7). When the value of the water pressure sensor (12) above the air injection ring (7) increases and fluctuates, record the air intake pressure at this time as the second pressure. Then open the drain pipe (12) and connect it with the horizontal pipe (111) to refill the water to saturation. Then refill the air and gradually increase the air intake pressure on the air injection ring (7). When the value of the water pressure sensor (12) below the air injection ring (7) increases and fluctuates, record the air intake pressure at this time as the third pressure.

8. The gas-water pressure balance experimental method as described in claim 7, characterized in that, After the first and second pressure tests are completed, repeat steps 2 and 3, adjust the height of the outlet end of the drain pipe (12) to be consistent with the overflow pipe (11), and close the water injection device (3). Inflate the cylinder (1) with gas through the air filling device (4) until the air inlet pressure is higher than the first pressure and lower than the second and third pressures. After no water flows out of the overflow pipe (11), increase the air pressure to the second or third pressure and monitor the flow rate of the overflow pipe and the amount of water flowing out of the drain pipe.

9. The gas-water pressure balance experimental method as described in claim 5, characterized in that, In the inflation test, the inflation pressure is increased from a static value to a stable value and held for a certain period of time. Then the water flow rate at the drain pipe (12) is measured and the value is recorded. Then the pressure is increased to a stable value and held for a certain period of time. Then the water flow rate at the drain pipe (12) is measured and the value is recorded. The above steps are repeated until no more water is discharged from the drain pipe (12).

10. The gas-water pressure balance experimental method as described in claim 9, characterized in that, During the inflation process, when no water is discharged from the drain pipe (12) at the bottom of the cylinder (1), the drain pipe (12) is closed. During the dwell time after the pressure value increases, the pressure value change at the water pressure sensor (2) above the air injection ring (7) is observed. When the pressure value of the corresponding water pressure sensor (2) changes, the inflation pressure value and the position of the corresponding water pressure sensor (2) are recorded.

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