Soil-rock interface shear-seepage coupling test device and method thereof

Abstract

The invention belongs to the technical field of geotechnical engineering tests, and discloses a soil-rock interface shear-seepage coupling test device which comprises a loading box composed of a loading box body, a loading box front cover plate and rollers, and further comprises a sliding box arranged in the loading box body and placed above the rollers; the stacked ring single shear box is connected to the interior of the sliding box in a sliding mode; and the displacement sensing device is arranged at the top of the inner cavity of the loading box body and is used for measuring the displacement amount of the stacked ring single shear box. The real shearing mechanical characteristics, seepage characteristics and failure modes of the soil-rock interface can be obtained under the coupling of a complex mechanical loading environment and an underground water seepage field, and more accurate and reliable theoretical basis and technical support are provided for design, construction and stability evaluation of geotechnical engineering.

Description

Technical Field

[0001] The invention belongs to the technical field of geotechnical engineering tests, and in particular relates to a soil-rock interface shear-seepage coupling test device and a method thereof. Background Art

[0002] The soil-rock interface, as the transition zone between soil and rock, often becomes a weak surface and potential slip surface in the stratum. In areas near rivers, it may also be a groundwater-enriched zone. In a complex geological environment, it is affected by the coupling of shear force and groundwater seepage, making the seepage and unloading mechanical behavior of this area extremely complex, and the impact on engineering stability is difficult to predict and evaluate.

[0003] The shear test of soil or rock alone is relatively mature, but the shear test technology and methods for the soil-rock interface have not yet been unified. In particular, scientific and efficient soil-rock interface shear-seepage coupling test methods are still quite lacking. The main difficulties currently exist are: (1) How to truly restore the high-pressure head directional seepage state at the soil-rock interface in the actual stratum; (2) How to protect the sensor and loading device while effectively collecting the required parameters; (3) How to achieve good airtightness and watertightness. The soil-rock interface shear-seepage coupling test devices and technologies currently disclosed do not solve the above problems well: some only achieve shear under saturated water conditions, which is far from the actual groundwater seepage environment; some devices have sensors and loading heads immersed in water for a long time, and their long-term working performance is questionable; and it is unknown whether the water-stopping measures that are feasible under normal pressure are also applicable to high pressure.

[0004] In addition, conventional direct shear tests have problems such as the shear surface being artificially defined and the uneven distribution of stress on the failure surface. In the shear problem at the soil-rock interface, the interface itself has complex undulating characteristics, and this characteristic will affect the distribution of the shear failure surface. The use of conventional direct shear tests will inevitably cause test errors. The stacked ring single shear test better compensates for the above defects and becomes an ideal means to study the shear mechanical properties of the soil-rock interface.

[0005] As geotechnical engineering construction progresses toward deeper and more complex geological conditions, accurately understanding the shear-seepage coupling characteristics of the soil-rock interface has become a critical issue that needs to be addressed in underground space development and underground engineering construction. Therefore, a test device and scientifically effective test methods that can simulate the soil-rock interface under complex stress and seepage conditions are urgently needed to fill the gaps in existing technology and provide a more reliable theoretical basis and technical support for the design, construction, and safety assessment of geotechnical engineering. Summary of the Invention

[0006] To solve the problems of poor reduction effect of the directional seepage state of the high-pressure water head at the soil-rock interface in the actual formation and poor protection effect on the protection sensors and loading devices on the premise of effectively collecting the required parameters in the above-mentioned background art, the present invention provides a shear-seepage coupling test device and method for the soil-rock interface.

[0007] To achieve the above object, the present invention provides the following technical solutions: A shear-seepage coupling test device for the soil-rock interface, comprising a loading box composed of a loading box body, a loading box front cover plate and rollers. The loading box body is arranged on the ground, the loading box front cover plate is detachably connected to the loading box body, and the rollers are installed on the bottom surface of the inner cavity of the loading box body. It further includes:

[0008] A sliding box, which is arranged inside the loading box body and placed above the rollers;

[0009] A stacked ring direct shear box, which is slidably connected inside the sliding box;

[0010] A displacement sensing device, which is arranged at the top of the inner cavity of the loading box body and is used to measure the displacement of the stacked ring direct shear box;

[0011] An axial loading jack, which is fixedly installed at the top of the inner cavity of the loading box body and is used to apply pressure to the specimen inside the stacked ring direct shear box;

[0012] A tangential loading jack, which is fixedly installed on one side wall of the inner cavity of the loading box body and is used to apply pressure to the sliding box;

[0013] A positioning mechanism, which is arranged in the inner cavity of the loading box body and is used to position the sliding box;

[0014] A water injection mechanism, which is arranged outside the loading box body and is used to inject water and drain water inside the sliding box;

[0015] A ventilation mechanism, which is arranged outside the loading box body and is used to increase or decrease the pressure inside the loading box.

[0016] Preferably, the sliding box includes a sliding box body, a sliding box front cover plate and limiting strips. The sliding box body is placed on the rollers, the limiting strips are symmetrically installed on the bottom surface of the inner cavity of the sliding box body, the sliding box front cover plate is detachably connected to the sliding box body, both the loading box front cover plate and the sliding box front cover plate are made of acrylic plates, and both the sliding box body and the loading box body are made of stainless steel plates.

[0017] Preferably, the stacked-ring direct shear box includes a top ring, an upper stacked ring, and a shear box. Both the top ring and the upper stacked ring are in a figure-eight shape. There are five rings in the upper stacked ring. A permeable stone with a rough bottom surface is placed inside the top ring. Permeable holes are provided on both sides of the top ring, the upper stacked ring, and the shear box, and a pin hole is provided on one side surface.

[0018] Preferably, a high-transparency Teflon coating is applied to the side surface of the top ring away from the upper stacked ring. The width direction after the combination of the top ring and the upper stacked ring fits the inner side wall after the combination of the sliding box body and the sliding box front cover plate.

[0019] Preferably, the displacement sensing device includes a pull-rod displacement meter, a deflection bracket, a fixed pulley, and a wire. Both the pull-rod displacement meter and the deflection bracket are fixedly installed at the top of the inner cavity of the loading box body. The fixed pulley is installed at the bottom of the deflection bracket. One end of the wire is connected to the pull-rod displacement meter after passing around the fixed pulley, and the other end is sequentially connected to the upper stacked ring.

[0020] Preferably, the positioning mechanism includes an adjusting roller, positioning angle blocks, and a positioning arc roller. The adjusting roller is rotationally sealed at a corner inside the loading box body. The positioning angle blocks are symmetrically installed at both ends of the adjusting roller. The positioning arc roller is installed on the adjusting roller and is located between the two positioning angle blocks. The positioning angle blocks are right trapezoids, and the positioning arc roller is elliptical.

[0021] Preferably, the water injection mechanism includes a high-pressure water pipe, a water distribution pipe, a first water valve, a second water valve, a water pump, and a flow meter. Both ends of the high-pressure water pipe pass through the loading box body and communicate with the inside of the sliding box body to form a closed loop. The first water valve, the water pump, and the flow meter are sequentially installed on the high-pressure water pipe. The water distribution pipe is communicated with the high-pressure water pipe and is located between the first water valve and the water pump. The second water valve is installed on the water distribution pipe.

[0022] Preferably, the ventilation mechanism includes a high-pressure air pipe, an air distribution pipe, a first air valve, a pressure gauge, an air pump, and a second air valve. One end of the high-pressure air pipe is communicated with the inside of the loading box body, and the other end is fixedly installed with the air pump. The first air valve and the pressure gauge are sequentially installed on the high-pressure air pipe. The air distribution pipe is communicated with the high-pressure air pipe and is located at one end of the first air valve away from the pressure gauge. The second air valve is installed on the air distribution pipe.

[0023] The present invention also provides a shear-seepage coupling test method for the soil-rock interface, and the specific steps are as follows.

[0024] S1: Place the stacked-ring direct shear box containing the shear specimen into the sliding box, place the top permeable stone, and fix it.

[0025] S2: Retract the axial loading jack and the tangential loading jack and push the sliding box into the loading box.

[0026] S3: Install the displacement sensing device, and then debug the displacement sensing device, the axial loading jack, and the tangential loading jack in sequence;

[0027] S4: Start the axial loading jack to load at the specified loading rate until the designed axial compression is reached and maintained, and then start the tangential loading jack to load at the specified loading rate;

[0028] S5: Record the test loading curve and the test process.

[0029] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0030] The present invention can obtain the true shear mechanical characteristics, seepage characteristics, and failure modes of the soil-rock interface under the coupling of a complex mechanical loading environment and a groundwater seepage field, providing a more accurate and reliable theoretical basis and technical support for the design, construction, and stability evaluation of geotechnical engineering.

[0031] Through the cooperation of the sliding box body, the positioning angle block, and the positioning arc roller, the present invention reaches the standard position of the test by moving the sliding box body along the inclined surface of the positioning angle block and being blocked by the positioning arc roller, facilitating the force balance of the axial loading jack and the tangential loading jack, and also facilitating the installation of the wire. After the position of the sliding box is fixed, the rotation of the sliding box body will not affect the test, improving the convenience of use. Description of the Drawings

[0032] Figure 1 is the front view of the internal structure of the loading box of the present invention;

[0033] Figure 2 is the present invention Figure 1 the enlarged view of the structure of A in;

[0034] Figure 3 is the side view of the internal structure of the loading box of the present invention;

[0035] Figure 4 is the top view of the internal structure of the loading box of the present invention;

[0036] Figure 5 is the detailed structure diagram of the stacked ring single shear box of the present invention;

[0037] Figure 6 is the detailed structure diagram of the positioning mechanism of the present invention;

[0038] Figure 7 is the schematic diagram of processing rock samples of the present invention Figure 1 ;

[0039] Figure 8 is the schematic diagram of processing rock samples of the present invention Figure 2 ;

[0040] Figure 9 Schematic diagram of processing rock samples for the present invention Figure 3 ;

[0041] Figure 10 Schematic diagram of processing rock samples for the present invention Figure 4 。

[0042] In the figure: 1. Loading box; 101. Loading box body; 102. Front cover plate of the loading box; 103. Roller; 2. Sliding box; 201. Sliding box body; 202. Front cover plate of the sliding box; 203. Limit strip; 3. Ring stack single shear box; 301. Top ring; 302. Upper ring stack; 303. Shear box; 4. Displacement sensing device; 401. Pull rod type displacement meter; 402. Direction changing bracket; 403. Fixed pulley; 404. Wire; 5. Axial loading jack; 6. Tangential loading jack; 7. Positioning mechanism; 701. Adjusting roller; 702. Positioning angle block; 703. Positioning arc roller; 8. Water injection mechanism; 801. High-pressure water pipe; 802. Water distribution pipe; 803. First water valve; 804. Second water valve; 805. Water pump; 806. Flowmeter; 9. Ventilation mechanism; 901. High-pressure air pipe; 902. Air distribution pipe; 903. First air valve; 904. Pressure gauge; 905. Air pump; 906. Second air valve. Specific embodiments

[0043] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0044] As Figures 1 to 10 shown, the present invention provides a shear-seepage coupling test device and method for the soil-rock interface, including a loading box 1 composed of a loading box body 101, a front cover plate 102 of the loading box, and a roller 103. The loading box body 101 is arranged on the ground, the front cover plate 102 of the loading box is detachably connected to the loading box body 101, and the roller 103 is installed on the inner bottom surface of the loading box body 101. It further includes:

[0045] A sliding box 2, which is arranged inside the loading box body 101 and placed above the roller 103;

[0046] A ring stack single shear box 3, which is slidably connected inside the sliding box 2;

[0047] A displacement sensing device 4, which is arranged at the top of the inner cavity of the loading box body 101 and is used to measure the displacement of the ring stack single shear box 3;

[0048] Axial loading jack 5 is fixedly installed at the top of the inner cavity of the loading box body 101 and is used to apply pressure to the specimen inside the stacked ring direct shear box 3;

[0049] Tangential loading jack 6 is fixedly installed on one side wall of the inner cavity of the loading box body 101 and is used to apply pressure to the sliding box 2;

[0050] Positioning mechanism 7 is arranged in the inner cavity of the loading box body 101 and is used to position the sliding box 2;

[0051] Water injection mechanism 8 is arranged outside the loading box body 101 and is used to inject water and drain water inside the sliding box 2;

[0052] Ventilation mechanism 9 is arranged outside the loading box body 101 and is used to increase or decrease the pressure inside the loading box 1.

[0053] With the above scheme: Through the cooperation of structures such as the sliding box 2, the stacked ring direct shear box 3, and the displacement sensing device 4, the true shear mechanical characteristics, seepage characteristics, and failure modes of the soil-rock interface under the coupling of a complex mechanical loading environment and a groundwater seepage field can be obtained, providing a more accurate and reliable theoretical basis and technical support for the design, construction, and stability evaluation of geotechnical engineering.

[0054] As Figure 3 、 4 shown, the sliding box 2 includes a sliding box body 201, a sliding box front cover plate 202, and a limiting strip 203. The sliding box body 201 is placed on the rollers 103. The limiting strip 203 is symmetrically installed on the bottom surface of the inner cavity of the sliding box body 201. The sliding box front cover plate 202 is detachably connected to the sliding box body 201. Both the loading box front cover plate 102 and the sliding box front cover plate 202 are made of acrylic plates, and both the sliding box body 201 and the loading box body 101 are made of stainless steel plates.

[0055] With the above scheme: The limiting strip 203 is set to fix the shear box 303, thereby simulating a rock with a stable position. And through the detachable loading box front cover plate 102 and sliding box front cover plate 202 made of unstained acrylic, the test can also be conveniently observed, realizing visualization during the test. At the same time, the connections between the loading box body 101 and the loading box front cover plate 102, and between the sliding box body 201 and the sliding box front cover plate 202 are also sealed to reduce the test error and improve the accuracy of the simulation test. The rollers 103 provided are fully lubricated with lubricating oil to reduce the friction when fitting with the sliding box body 201; The connection between the limiting strip 203 and the sliding box body 201 can be a slot connection, a bolt connection, or determined according to actual needs.

[0056] As Figure 5As shown in the figure, the stacked-ring single-shear box 3 includes a top ring 301, an upper stacked ring 302, and a shear box 303. Both the top ring 301 and the upper stacked ring 302 are in a figure-eight shape. The upper stacked ring 302 has a total of five rings. A permeable stone with a rough bottom surface is placed inside the top ring 301. Permeable holes are provided on both sides of the top ring 301, the upper stacked ring 302, and the shear box 303, and a pin hole is provided on one side surface.

[0057] With the above solution: The axial loading jack 5 limits the permeable stone in the horizontal direction, and the rough lower surface of the permeable stone can limit the horizontal displacement of the lower soil mass. The provided permeable holes enable the free inflow and outflow of water in the sliding box 2. The provided pin hole ensures that there is no relative movement between multiple upper stacked rings 302 during sample loading.

[0058] As Figure 4 、 5 shown in the figure, a high-transparency Teflon coating is applied to the side surface of the top ring 301 away from the upper stacked ring 302. The combined width direction of the top ring 301 and the upper stacked ring 302 fits against the inner side wall of the combined sliding box body 201 and the sliding box front cover plate 202.

[0059] With the above solution: By applying the high-transparency Teflon coating, the sliding friction is reduced. The sliding box 2 fits with the stacked-ring single-shear box 3 and can ensure that the water in the sliding box 2 completely flows through the shear specimen, guaranteeing the accuracy of the test.

[0060] As Figure 1 、 2 shown in the figure, the displacement sensing device 4 includes a pull-rod displacement gauge 401, a deflection bracket 402, a fixed pulley 403, and a wire 404. Both the pull-rod displacement gauge 401 and the deflection bracket 402 are fixedly installed on the top of the inner cavity of the loading box body 101. The fixed pulley 403 is installed at the bottom of the deflection bracket 402. One end of the wire 404 is connected to the pull-rod displacement gauge 401 after passing around the fixed pulley 403, and the other end is sequentially connected to the upper stacked ring 302.

[0061] With the above solution: During the shearing process, as the upper stacked ring 302 moves, the wire and the displacement gauge probe are pulled to obtain readings.

[0062] As Figure 6 shown in the figure, the positioning mechanism 7 includes an adjusting roller 701, a positioning angle block 702, and a positioning arc roller 703. The adjusting roller 701 is sealed and rotates at a corner inside the loading box body 101. The positioning angle blocks 702 are symmetrically installed at both ends of the adjusting roller 701. The positioning arc roller 703 is installed on the adjusting roller 701 and is located between the two positioning angle blocks 702. The positioning angle block 702 is a right trapezoid, and the positioning arc roller 703 is an ellipse.

[0063] Adopting the above - mentioned solution: When the sliding box body 201 is pushed into the inside of the loading box body 101, the sliding box body 201 moves along the inclined plane of the positioning angle block 702 and is blocked by the positioning arc roller 703, so that the sliding box body 201 reaches the standard position of the test, which is convenient for the force balance of the axial loading jack 5 and the tangential loading jack 6, and also convenient for the installation of the wire 404, thus improving the convenience of the device.

[0064] As Figure 1 、 4 shown, the water injection mechanism 8 includes a high - pressure water pipe 801, a water distribution pipe 802, a first water valve 803, a second water valve 804, a water pump 805 and a flow meter 806. The two ends of the high - pressure water pipe 801 respectively pass through the loading box body 101 and communicate with the inside of the sliding box body 201 to form a closed loop. The first water valve 803, the water pump 805 and the flow meter 806 are sequentially installed on the high - pressure water pipe 801. The water distribution pipe 802 is communicated with the high - pressure water pipe 801 and is located between the first water valve 803 and the water pump 805. The second water valve 804 is installed on the water distribution pipe 802.

[0065] Adopting the above - mentioned solution: Through the cooperation of the above - mentioned structure, it can provide environmental simulation under the condition of water for the test, improve the applicability of the device. The length of the high - pressure water pipe 801 between the sliding box body 201 and the loading box body 101 is sufficient, preventing the water pipe from being damaged due to insufficient length during the shearing process.

[0066] As Figure 4 shown, the ventilation mechanism 9 includes a high - pressure air pipe 901, an air distribution pipe 902, a first air valve 903, a pressure gauge 904, an air pump 905 and a second air valve 906. One end of the high - pressure air pipe 901 is communicated with the inside of the loading box body 101, and the other end is fixedly installed with the air pump 905. The first air valve 903 and the pressure gauge 904 are sequentially installed on the high - pressure air pipe 901. The air distribution pipe 902 is communicated with the high - pressure air pipe 901 and is located at one end of the first air valve 903 away from the pressure gauge 904. The second air valve 906 is installed on the air distribution pipe 902.

[0067] Adopting the above - mentioned solution: It can provide high - pressure conditions for the test. At the initial stage of the test, when injecting water into the sliding box 2, it acts as an exhaust port to realize effective water injection into the internal closed space; before the shear test, it acts as an air inlet. By turning on the air pump 905, the internal pressure of the closed box body is increased to reflect the real groundwater pressure. It improves the applicability of the device and also improves the simulation effect of the device.

[0068] The specimen is divided into a lower rock specimen and an upper soil specimen. The specific preparation method is as follows:

[0069] 1. Lower rock specimen

[0070] The rock specimens can be prepared by mechanical cutting, water jet, 3D printing, etc. from intact and hard rocks. Among them, for rock specimens with regular and simple shapes (such as square boss shape, serrated undulation), they can be made by mechanical cutting and water jet processing. For rock specimens with irregular and complex shapes, they can be printed with rock-like materials by 3D printing. Among them, the rock specimens with irregular and complex shapes include the n-order undulation specimens designed according to fractal geometry and the specimens designed according to the geometric morphology of the real soil-rock interface. The geometric morphology of the real soil-rock interface can be obtained through image scanning and digital processing technology and restored by 3D printing technology.

[0071] 2. Upper soil specimens

[0072] For the upper soil specimens, different soil samples such as clay and sand can be used, or a soil-rock mixture can be prepared. When sand is used, fine filter screens need to be installed at the openings on both sides of the stacked rings to prevent sand particles from being carried out by seepage. When preparing the soil samples, the compactness needs to be strictly guaranteed, and the layered filling method is used for preparation, and the contact surface between adjacent layers is roughened.

[0073] The test steps of the conventional stacked ring direct simple shear test are as follows:

[0074] S1: Remove the front cover plate 102 of the loading box and the front cover plate 202 of the sliding box;

[0075] S2: Install the stacked ring direct simple shear box 3 and insert the pin;

[0076] S3: Prepare the specimen in the stacked ring direct simple shear box 3 according to the shear specimen preparation method;

[0077] S4: Place the stacked ring direct simple shear box 3 containing the shear specimen into the sliding box body 201, place the top permeable stone on it, fix it with the limit strip 203, and pull out the pin;

[0078] S5: Retract the axial loading jack 5 and the tangential loading jack 6;

[0079] S6: Push the sliding box 2 along the inner side of the positioning angle block 702 into the loading box 1 until it is in pressure contact with the positioning arc roller 703, and then rotate the positioning mechanism 7 upward by 90 degrees;

[0080] S7: Install the displacement sensing device 4 and debug it;

[0081] S8: Start the axial loading jack 5 and slowly move it downward until it falls into the groove on the upper surface of the top permeable stone, and continue to move until the data acquisition instrument has a reading;

[0082] S9: Start the tangential loading jack 6 and slowly move it to the left until it is in preliminary contact with the sliding box body 201, and the data acquisition instrument has a reading;

[0083] S10: Install the front cover plate 202 of the sliding box so that it closely adheres to the stacked-ring direct shear box 3;

[0084] S11: Zero the readings of each sensor;

[0085] S12: Start the axial loading jack 5 and load to the designed axial pressure at the specified loading rate and maintain it;

[0086] S13: Start the tangential loading jack 6 and load at the specified loading rate;

[0087] S14: Record the test loading curve and the test process.

[0088] The test steps for the shear-seepage coupling stacked-ring direct shear test under normal pressure head are as follows:

[0089] S1: Remove the front cover plate 102 of the loading box and the front cover plate 202 of the sliding box;

[0090] S2: Install the stacked-ring direct shear box 3 and insert the pin;

[0091] S3: Prepare the specimen in the stacked-ring direct shear box 3 according to the shear specimen preparation method;

[0092] S4: Place the stacked-ring direct shear box 3 containing the shear specimen into the sliding box body 201, place the top permeable stone on it, fix it with the limit strip 203, and pull out the pin;

[0093] S5: Retract the axial loading jack 5 and the tangential loading jack 6;

[0094] S6: Push the sliding box 2 along the inner side of the positioning angle block 702 into the loading box 1 until it is in pressure contact with the positioning arc roller 703, and then rotate the positioning mechanism 7 upward by ninety degrees;

[0095] S7: Install and debug the displacement sensing device 4;

[0096] S8: Start the axial loading jack 5 and slowly move downward until it falls into the slot on the upper surface of the top permeable stone, and continue to move until the data acquisition instrument shows readings;

[0097] S9: Start the tangential loading jack 6 and slowly move to the left until it is in preliminary contact with the sliding box body 201, and the data acquisition instrument shows readings;

[0098] S10: Install the front cover plate 202 of the sliding box so that it closely adheres to the stacked-ring direct shear box 3;

[0099] S11: Turn on the water pump 805, open the second water valve 804. The water level on the left side inside the sliding box 2 rises rapidly and remains below the top surface of the stacked-ring direct shear box 3. It seeps through the stacked-ring direct shear box 3 to the right, and the water level on the right side rises slowly until it is equal to the left side and remains unchanged, indicating that the specimen is fully saturated with water. Then close the second water valve 804 and turn off the water pump 805.

[0100] S12: Open the first water valve 803, turn on the water pump 805, and adjust the pumping pressure to form a directional water flow from left to right inside the sliding box 2, while controlling the water levels on both sides inside the sliding box 2 to remain unchanged.

[0101] S13: Zero the readings of each sensor.

[0102] S14: Start the axial loading jack 5 and load to the designed axial compression and maintain it at the specified loading rate.

[0103] S15: Start the tangential loading jack 6 and load at the specified loading rate.

[0104] S16: Record the test loading curve and the test process.

[0105] S17: After the test, stop the tangential loading jack 6, turn off the water pump 805, open the second water valve 804, drain the water inside the loading box 1, retract the axial loading jack 5 and the tangential loading jack 6, and clean the test device.

[0106] The test steps for the shear-seepage coupling stacked-ring direct shear test under high-pressure water head are as follows:

[0107] S1: Remove the front cover plate 102 of the loading box and the front cover plate 202 of the sliding box.

[0108] S2: Install the stacked-ring direct shear box 3 and insert the pin.

[0109] S3: Prepare the specimen inside the stacked-ring direct shear box 3 according to the shear specimen preparation method.

[0110] S4: Place the stacked-ring direct shear box 3 containing the shear specimen into the sliding box body 201, place the top permeable stone on it, fix it with the limit strip 203, and pull out the pin.

[0111] S5: Retract the axial loading jack 5 and the tangential loading jack 6.

[0112] S6: Push the sliding box 2 into the loading box 1 along the inner side of the positioning angle block 702 until it is in pressure contact with the positioning arc roller 703, and then rotate the positioning mechanism 7 ninety degrees upward.

[0113] S7: Install and debug the displacement sensing device 4.

[0114] S8: Start the axial loading jack 5, slowly move it downward, let it fall into the slot on the upper surface of the top pervious stone, and continue to move until the data acquisition instrument shows a reading.

[0115] S9: Start the tangential loading jack 6, slowly move it to the left, pre-contact it with the sliding box body 201, and the data acquisition instrument shows a reading.

[0116] S10: Install the front cover plate 202 of the sliding box to make it closely fit with the stacked ring direct shear box 3.

[0117] S11: Install the front cover plate 102 of the loading box.

[0118] S12: Open the second air valve 906, start the water pump 805, open the second water valve 804. The water level on the left side in the sliding box 2 rises rapidly and remains below the top surface of the stacked ring direct shear box 3, seeps through the stacked ring direct shear box 3 to the right, and the water level on the right side rises slowly until it is equal to the left side and remains unchanged, indicating that the specimen is fully saturated with water. Then close the second water valve 804 and turn off the water pump 805.

[0119] S13: Close the second air valve 906, start the air pump 905, open the first air valve 903, pressurize the loading box 1 to the set value, then close the first air valve 903 and turn off the air pump 905.

[0120] S14: Open the first water valve 803, start the water pump 805, adjust the pumping pressure to form a directional water flow from left to right in the sliding box 2, and at the same time control the water level heights on both sides in the sliding box 2 to remain unchanged.

[0121] S15: Zero the readings of each sensor.

[0122] S16: Start the axial loading jack 5, load it to the designed axial pressure at the specified loading rate and maintain it.

[0123] S17: Start the tangential loading jack 6 and load it at the specified loading rate.

[0124] S18: Record the test loading curve and the test process.

[0125] S19: After the test, stop the tangential loading jack 6, open the second air valve 906 to release the pressure outward, turn off the water pump 805, open the second water valve 804 to drain the water in the loading box 1, retract the axial loading jack 5 and the tangential loading jack 6, and clean the test device.

[0126] It should be noted that in this text, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or further includes elements inherent to such process, method, article or device.

[0127] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. Shear-seepage coupling test device for soil-rock interface, characterized in that: Comprising a loading box (1) consisting of a loading box body (101), a front cover plate (102) of the loading box, and rollers (103), the loading box body (101) is arranged on the ground, the front cover plate (102) of the loading box is detachably connected to the loading box body (101), the rollers (103) are installed on the bottom surface of the inner cavity of the loading box body (101), and further comprising: A sliding box (2), the sliding box (2) is arranged inside the loading box body (101) and placed above the rollers (103); A stacked ring direct shear box (3), the stacked ring direct shear box (3) is slidably connected inside the sliding box (2); A displacement sensing device (4), the displacement sensing device (4) is arranged at the top of the inner cavity of the loading box body (101) and is used for measuring the displacement of the stacked ring direct shear box (3); An axial loading jack (5), the axial loading jack (5) is fixedly installed at the top of the inner cavity of the loading box body (101) and is used for pressing the specimen inside the stacked ring direct shear box (3); A tangential loading jack (6), the tangential loading jack (6) is fixedly installed on one side wall of the inner cavity of the loading box body (101) and is used for pressing the sliding box (2); A positioning mechanism (7), the positioning mechanism (7) is arranged in the inner cavity of the loading box body (101) and is used for positioning the sliding box (2); A water injection mechanism (8), the water injection mechanism (8) is arranged outside the loading box body (101) and is used for injecting and draining water inside the sliding box (2); A ventilation mechanism (9), the ventilation mechanism (9) is arranged outside the loading box body (101) and is used for increasing or decreasing the pressure inside the loading box (1).

2. The shear-seepage coupling test device for the soil-rock interface according to claim 1, wherein: The sliding box (2) includes a sliding box body (201), a front cover plate (202) of the sliding box, and a limiting strip (203). The sliding box body (201) is placed on the rollers (103), the limiting strip (203) is symmetrically installed on the bottom surface of the inner cavity of the sliding box body (201), the front cover plate (202) of the sliding box is detachably connected to the sliding box body (201), both the front cover plate (102) of the loading box and the front cover plate (202) of the sliding box are made of acrylic plates, and both the sliding box body (201) and the loading box body (101) are made of stainless steel plates.

3. The shear-seepage coupling test device for the soil-rock interface according to claim 2, characterized in that: The stacked ring direct shear box (3) includes a top ring (301), an upper stacked ring (302), and a shear box (303). Both the top ring (301) and the upper stacked ring (302) are in a shape of a Chinese character 'hui'. There are five rings in total for the upper stacked ring (302). A permeable stone with a rough bottom surface is placed inside the top ring (301). Permeable holes are provided on both sides of the top ring (301), the upper stacked ring (302), and the shear box (303), and a pin hole is provided on one side surface.

4. The shear-seepage coupling test device for the soil-rock interface according to claim 3, characterized in that: A high transparency Teflon coating is applied to the side surface of the top ring (301) away from the upper stacked ring (302). The width direction after the combination of the top ring (301) and the upper stacked ring (302) fits the inner side wall after the combination of the sliding box body (201) and the front cover plate (202) of the sliding box.

5. The shear-seepage coupling test device for the soil-rock interface according to claim 3, wherein: The displacement sensing device (4) includes a pull-rod type displacement meter (401), a direction-changing bracket (402), a fixed pulley (403) and a wire (404). The pull-rod type displacement meter (401) and the direction-changing bracket (402) are both fixedly installed at the top inside the cavity of the loading box body (101). The fixed pulley (403) is installed at the bottom of the direction-changing bracket (402). One end of the wire (404) is connected to the pull-rod type displacement meter (401) after passing around the fixed pulley (403), and the other end is sequentially connected to the upper stacked ring (302).

6. The shear-seepage coupling test device for the soil-rock interface according to claim 1, characterized in that: The positioning mechanism (7) includes an adjusting roller (701), positioning angle blocks (702) and a positioning arc roller (703). The adjusting roller (701) rotates in a sealed manner at a corner inside the loading box body (101). The positioning angle blocks (702) are symmetrically installed at both ends of the adjusting roller (701). The positioning arc roller (703) is installed on the adjusting roller (701) and is located between the two positioning angle blocks (702). The positioning angle blocks (702) are right trapezoids, and the positioning arc roller (703) is elliptical.

7. The shear-seepage coupling test device for the soil-rock interface according to claim 2, characterized in that: The water injection mechanism (8) includes a high-pressure water pipe (801), a water distribution pipe (802), a first water valve (803), a second water valve (804), a water pump (805) and a flow meter (806). Both ends of the high-pressure water pipe (801) pass through the loading box body (101) and communicate with the inside of the sliding box body (201) to form a closed loop. The first water valve (803), the water pump (805) and the flow meter (806) are sequentially installed on the high-pressure water pipe (801). The water distribution pipe (802) communicates with the high-pressure water pipe (801) and is located between the first water valve (803) and the water pump (805). The second water valve (804) is installed on the water distribution pipe (802).

8. The shear-seepage coupling test device for the soil-rock interface according to claim 1, wherein: The air venting mechanism (9) includes a high-pressure air pipe (901), an air distribution pipe (902), a first air valve (903), a pressure gauge (904), an air pump (905) and a second air valve (906). One end of the high-pressure air pipe (901) communicates with the inside of the loading box body (101), and the other end is fixedly installed with the air pump (905). The first air valve (903) and the pressure gauge (904) are sequentially installed on the high-pressure air pipe (901). The air distribution pipe (902) communicates with the high-pressure air pipe (901) and is located at the end of the first air valve (903) away from the pressure gauge (904). The second air valve (906) is installed on the air distribution pipe (902).

9. The shear-seepage coupling test method for the soil-rock interface according to claim 1, characterized in that: The specific steps are as follows: S1: Place the stacked-ring single shear box (3) containing the shear specimen into the sliding box (2), place the top permeable stone, and fix them. S2: Retract the axial loading jack (5) and the tangential loading jack (6), and push the sliding box (2) into the loading box (1). S3: Install the displacement sensing device (4), and sequentially debug the displacement sensing device (4), the axial loading jack (5) and the tangential loading jack (6). S4: Start the axial loading jack (5) to load at the specified loading rate until the design axial compression is reached and maintained, and then start the tangential loading jack (6) to load at the specified loading rate. S5: Record the test loading curve and the test process.

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