Testing device and method for simulating influence of hydraulic circulation on soil and water of soil body

Abstract

The invention discloses a testing device and method for simulating the influence of hydraulic circulation on soil water of a soil body. The testing device comprises an air pressure supply system, a water pressure supply system, a pressure chamber, an effluent collecting and measuring device and a data processing computer, an air inlet pipeline and a water inlet pipeline are arranged at the top of the pressure chamber, a water outlet is formed in the bottom of the pressure chamber, and a top cover of the pressure chamber is detachable; the air pressure supply system is used for providing air pressure for the pressure chamber, the water pressure supply system is used for providing hydraulic gradient for the pressure chamber, the effluent collecting and measuring device is used for collecting and measuring the water yield of the pressure chamber, and the data processing computer is used for collecting data of the effluent collecting and measuring device and processing the data. The invention provides a device and a method for testing a soil-water characteristic curve of a soil body under the influence of hydraulic circulation, which are used for simulating a change rule of matrix suction of the soil body under the action of the hydraulic circulation and laying a foundation for further analyzing unsaturated shear strength of the soil body under the action of the hydraulic circulation.

Description

Technical Field

[0001] The invention relates to the field of soil mechanics testing and geotechnical engineering technology, and in particular to a testing device and method for simulating the influence of hydraulic circulation on soil and water. Background Art

[0002] The shear strength of soil changes significantly under the action of hydrodynamics, which further affects the stability of geotechnical engineering, such as the stability of reservoir slopes and foundation pit slopes. The slopes of the reservoir are affected by the rise and fall of the reservoir water level, and the hydraulic gradient will fluctuate and reverse frequently. The unsaturated seepage characteristics of the soil under the action of hydraulic gradient circulation further affect its strength characteristics, which has an important impact on the stability of the reservoir slopes. At present, there is a lack of relevant test equipment for the unsaturated seepage law of soil under the influence of hydraulic circulation. Summary of the invention

[0003] Purpose of the invention: In view of the above shortcomings, the present invention provides a testing device and method for simulating the influence of hydraulic circulation on soil water.

[0004] Technical solution: To solve the above problems, the present invention adopts a test device that simulates the influence of hydraulic circulation on soil water, including an air supply pressure system, a water supply pressure system, a pressure chamber, a water outlet collection and measurement device, and a data processing computer; the top of the pressure chamber is provided with an air inlet pipe and a water inlet pipe, the bottom of the pressure chamber is provided with a drain port, and the top cover of the pressure chamber is removable; the air supply pressure system is used to provide air pressure for the pressure chamber, the water supply pressure system is used to provide a hydraulic gradient for the pressure chamber, the water outlet collection and measurement device is used to collect and measure the water outlet of the pressure chamber, and the data processing computer is used to collect data from the water outlet collection and measurement device and perform data processing.

[0005] Furthermore, the air pressure supply system is an air pump.

[0006] Furthermore, the air pressure supply system is provided with an air pressure pipeline for connecting to the pressure chamber, and the air pressure pipeline is made of airtight transparent plastic material.

[0007] Furthermore, the water supply pressure system includes a lifting device and a water tank connected to the lifting device. The height of the water tank is adjusted by the lifting device to provide different hydraulic gradients for the pressure chamber.

[0008] Furthermore, the water tank is provided with a water pressure pipe for connecting with the pressure chamber, and the water pressure pipe is made of a watertight transparent plastic material.

[0009] Furthermore, the lifting device includes a manual winch and a pulley, the manual winch is connected to the water tank via a steel wire rope, and the steel wire rope is wound around the pulley.

[0010] Furthermore, the water collection and measurement device includes a balance and a measuring cylinder placed on the balance.

[0011] Furthermore, a pressure gauge is installed on the pressure chamber to obtain the pressure value in the pressure chamber.

[0012] Furthermore, a safety valve is installed on the pressure chamber.

[0013] The present invention also provides a test method for the test device for simulating the influence of hydraulic circulation on soil water, providing permeable stone, clay board, and test soil, and specifically comprising the following steps:

[0014] Step 1: Open the top cover of the pressure chamber, and lay permeable stones and test soil on the bottom surface of the pressure chamber from bottom to top. After laying, cover the top cover and seal the pressure chamber;

[0015] Step 2: Connect the water supply pressure system to the water inlet pipe, adjust the water supply pressure system to provide a preset hydraulic gradient for the pressure chamber, and the water flows out from the drain port;

[0016] Step 3, connect the water supply pressure system to the drain outlet, adjust the water supply pressure system to provide the same hydraulic gradient as in step 2 to the pressure chamber, and the water flows out from the water inlet pipe;

[0017] Step 4, repeat steps 2 and 3 to obtain the soil under the influence of multiple hydraulic cycles;

[0018] Step 5: Replace the permeable stone with a clay plate, connect the air supply pressure system to the air inlet pipe, and connect the water collection and measurement device to the drain outlet;

[0019] Step 6: Make the air supply pressure system provide a stable pressure until the amount of water collected by the water collection and measurement device does not change; increase the set pressure value of the air supply pressure system and continue to provide a stable pressure until the amount of water collected by the water collection and measurement device does not change;

[0020] Step 7, repeat step 6 multiple times, the data processing computer collects the water output measured by the water collection and measurement device at each pressure value, and performs data processing to obtain the saturation corresponding to the matrix suction of the soil under the influence of hydraulic circulation.

[0021] Beneficial effect: Compared with the prior art, the significant advantage of the present invention is that it provides a testing device and a testing method for the soil-water characteristic curve of soil under the influence of hydraulic circulation, which is used to simulate the changing law of soil matrix suction under the action of hydraulic circulation, and lays the foundation for further analysis of the unsaturated shear strength of soil under the action of hydraulic circulation. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the overall structure of the testing device of the present invention;

[0023] Figure 2 It is the water-soil characteristic curve measured by the present invention. DETAILED DESCRIPTION

[0024] like Figure 1 As shown, a test device for simulating the influence of hydraulic circulation on soil and water in this embodiment includes an air supply pressure system 1, a water supply pressure system 2, a pressure chamber 11, a water collection and measurement device 14, and a data processing computer 15. The pressure chamber 11 includes a detachable top cover, a base, and a cylinder fixed between the top cover and the base. The top of the pressure chamber 11 is provided with an air inlet pipe 6 and a water inlet pipe 7, and the bottom of the pressure chamber 11 is provided with a drain port 12. The pressure chamber 11 is also equipped with a pressure gauge 8 and a safety valve 9. The pressure gauge 8 is used to obtain the pressure value in the pressure chamber 11, and the safety valve 9 is used to ensure that the pressure of the pressure chamber is within a safe range when it is used.

[0025] The air pressure system 1 is an air pump, which is used to provide air pressure to the pressure chamber 11. The air pressure system 1 is provided with an air pressure pipe 4 for connecting to the pressure chamber 11, and the air pressure pipe 4 is made of airtight transparent plastic material. The water pressure system 2 is used to provide a hydraulic gradient for the pressure chamber 11. The water pressure system 2 includes a manual winch, a pulley, and a water tank. The manual winch is connected to the water tank through a steel strand, and the steel strand is wound on the pulley. The height of the water tank is adjusted by the manual winch, thereby adjusting the hydraulic gradient of the water pressure system 2. The water tank is provided with a water pressure pipe 3 for connecting to the pressure chamber 11, and the water pressure pipe 3 is made of watertight transparent plastic material. The water outlet collection and measurement device 14 includes a balance and a measuring cylinder placed on the balance, and the water outlet is accurately measured by the balance reading. The data processing computer 15 is used to collect data from the water outlet collection and measurement device 14 and perform data processing.

[0026] This embodiment also provides a test method for the test device for simulating the influence of hydraulic circulation on soil water, which specifically includes the following steps:

[0027] Step 1: Open the top cover of the pressure chamber 11, and lay permeable stones and test soil 10 on the bottom surface of the pressure chamber 11 from bottom to top. After laying, cover the top cover and seal the pressure chamber 11.

[0028] Step 2: Connect the water supply pressure system 2 to the water inlet pipe 7, and the air inlet pipe 6 is closed. Adjust the water supply pressure system 2 to provide a preset hydraulic gradient for the pressure chamber 11. In this embodiment, the hydraulic gradient is set to 2.4. Water flows into the pressure chamber 11 through the water inlet pipe 7 and flows in the sample, and flows out from the water outlet and air outlet 13 of the pressure chamber through the permeable stone at the bottom of the soil body 10. After 10 minutes of continuous action, turn off the water supply pressure system 2.

[0029] Step 3, connect the water supply pressure system 2 to the drain outlet 12, adjust the water supply pressure system 2 to provide the pressure chamber 11 with the same hydraulic gradient as in step 2, and the water flows into the pressure chamber through the pressure chamber water outlet and air outlet 13, and flows out from the water inlet pipe 7 for 10 minutes, thereby realizing a hydraulic circulation of the soil 10.

[0030] Step 4: Repeat steps 2 and 3 to obtain the soil under the influence of multiple hydraulic cycles.

[0031] Step 5: Replace the permeable stone with a clay plate, connect the air supply pressure system 1 to the air inlet pipe 6 , and connect the water collection and measurement device 14 to the drain outlet 12 .

[0032] Step 6: Make the air supply pressure system 1 provide a stable pressure until the amount of water collected by the water collection and measuring device 14 does not change; increase the set pressure value of the air supply pressure system 1 and continue to provide a stable pressure until the amount of water collected by the water collection and measuring device 14 does not change.

[0033] Step 7, repeat step 6 multiple times. In this embodiment, the air supply pressure system 1 is set to have an air inlet pressure of 50 kPa, 100 kPa, 150 kPa, 200 kPa, 250 kPa, 300 kPa, 350 kPa, and 400 kPa. The data processing computer 15 collects the water output measured by the water output collection and measurement device 14 at each pressure value, and performs data processing to obtain the saturation corresponding to the matrix suction of the soil under the influence of the hydraulic cycle.

[0034] The specific data processing method is as follows: Determine the dry density ρ of the test soil before the test d and saturation density ρ sat , according to the dry density ρ d The weight of the soil particles m can be calculated from the volume V of the pressure chamber s

[0035] m s =ρ d ·V

[0036] In the saturated state, according to the saturation density ρ sat The pore volume V of the soil sample can be obtained by combining the volume V of the pressure chamber v , that is, the volume of the liquid at this time V w , ρ w is the density of water.

[0037]

[0038] The inlet pressure value is the matrix suction value. When the water output is measured by the water collection and measurement system and remains stable, it is considered that the internal matrix suction of the test soil is the set value at this time. The soil saturation S corresponding to each level can be calculated through the water output weight m1 of each level.r .

[0039]

[0040] The data processing computer can calculate the water-soil characteristic curve of the soil under the influence of hydraulic circulation based on the obtained matrix suction and corresponding saturation data, such as Figure 2 shown.

[0041] The present invention provides a soil-water characteristic curve testing device and a testing method for soil under the influence of hydraulic circulation, which are used to simulate the changing law of soil matrix suction under the action of hydraulic circulation, and lay a foundation for further analyzing the unsaturated shear strength of soil under the action of hydraulic circulation.

Claims

1. A test device for simulating the influence of hydraulic circulation on soil water, characterized in that: The invention comprises an air pressure supply system (1), a water pressure supply system (2), a pressure chamber (11), a water outlet collection and measurement device (14), and a data processing computer (15); the top of the pressure chamber (11) is provided with an air inlet pipe (6) and a water inlet pipe (7); the bottom of the pressure chamber (11) is provided with a water outlet (12); and the top cover of the pressure chamber (11) is detachable; the air pressure supply system (1) is used to provide air pressure for the pressure chamber (11); the water pressure supply system (2) is used to provide a hydraulic gradient for the pressure chamber (11); the water outlet collection and measurement device (14) is used to collect and measure the water outlet of the pressure chamber (11); and the data processing computer (15) is used to collect data of the water outlet collection and measurement device (14) and perform data processing.

2. The testing device for simulating the influence of hydraulic circulation on soil water as claimed in claim 1, characterized in that: The air pressure supply system (1) is an air pump.

3. The testing device for simulating the influence of hydraulic circulation on soil water as claimed in claim 1, characterized in that: The air pressure supply system (1) is provided with an air pressure pipeline (4) for connecting to the pressure chamber (11), and the air pressure pipeline (4) is made of airtight transparent plastic material.

4. The testing device for simulating the influence of hydraulic circulation on soil water as claimed in claim 1, characterized in that: The water pressure supply system (2) comprises a lifting device and a water tank connected to the lifting device. The height of the water tank is adjusted by the lifting device to provide different hydraulic gradients for the pressure chamber (11).

5. The testing device for simulating the influence of hydraulic circulation on soil water as claimed in claim 4, characterized in that: The water tank is provided with a water pressure pipe (3) for connecting with the pressure chamber (11); the water pressure pipe (3) is made of a watertight transparent plastic material.

6. The testing device for simulating the influence of hydraulic circulation on soil water as claimed in claim 4, characterized in that: The lifting device comprises a manual winch and a pulley. The manual winch is connected to the water tank through a steel strand, and the steel strand is wound around the pulley.

7. The testing device for simulating the influence of hydraulic circulation on soil water as claimed in claim 1, characterized in that: The effluent collection and measurement device (14) comprises a balance and a measuring cylinder placed on the balance.

8. The testing device for simulating the influence of hydraulic circulation on soil water as claimed in claim 1, characterized in that: The pressure chamber (11) is also provided with a pressure gauge (8) for obtaining the pressure value in the pressure chamber (11).

9. The testing device for simulating the influence of hydraulic circulation on soil water as claimed in claim 1, characterized in that: A safety valve (9) is also installed on the pressure chamber (11).

10. A testing method for the testing device for simulating the effect of hydraulic circulation on soil water according to any one of claims 1 to 9, characterized in that: Providing permeable stone, clay board and test soil, specifically including the following steps: Step 1, open the top cover of the pressure chamber (11), and lay permeable stones and test soil (10) on the inner bottom surface of the pressure chamber (11) from bottom to top in sequence. After the laying is completed, cover the top cover and seal the pressure chamber (11); Step 2, connecting the water supply pressure system (2) to the water inlet pipe (7), adjusting the water supply pressure system (2) to provide a preset hydraulic gradient for the pressure chamber (11), and the water flows out from the drain port (12); Step 3, connecting the water supply pressure system (2) to the drain outlet (12), adjusting the water supply pressure system (2) to provide the pressure chamber (11) with the same hydraulic gradient as in step 2, and the water flows out from the water inlet pipe (7); Step 4, repeat steps 2 and 3 to obtain the soil under the influence of multiple hydraulic cycles; Step 5: Replace the permeable stone with a clay plate, connect the air supply pressure system (1) to the air inlet pipe (6), and connect the water collection and measurement device (14) to the drain outlet (12); Step 6: The air supply pressure system (1) provides a stable pressure until the amount of water collected by the water collection and measurement device (14) remains unchanged; the air supply pressure system (1) sets a pressure value and continues to provide a stable pressure until the amount of water collected by the water collection and measurement device (14) remains unchanged; Step 7, repeating step 6 multiple times, the data processing computer (15) collects the water output measured by the water output collection and measurement device (14) at each pressure value, and performs data processing to obtain the saturation corresponding to the matrix suction of the soil under the influence of hydraulic circulation.

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