Soft rock cavern roof anchoring body seepage water simulation device and method

Abstract

The invention discloses a soft rock cavern roof anchoring body seepage water simulation device and method. In the device, a water tank, a water pump device and a seepage water frame are sequentially connected through a water conveying pipe; the water seepage and spraying frame comprises a water seepage and spraying simulation box and a punching baffle, the punching baffle is installed in the water seepage and spraying simulation box and divides the interior of the water seepage and spraying simulation box into an upper space and a lower space, the upper space is a water storage room, and an anchored rock test piece is placed in the lower space; the sensing system comprises a water level controller and a water level sensor, the water level controller is installed on the water pump device, the water level sensor is installed in a water storage room on the upper portion of the seepage water simulation box, and the water level controller controls operation of the water pump device through seepage water frame water level signals transmitted by the water level sensor. The invention also discloses a test method thereof. The influence of different seepage paths and seepage flows of underground water on the bearing performance of the soft rock cavern roof anchoring structure is simulated, and the problems that an existing test water immersion mode does not conform to the reality and the water immersion result is poor in reliability are solved.

Description

Technical Field

[0001] The invention relates to a soft rock seepage simulation device, in particular to a soft rock cave roof anchor body seepage simulation device and method. Background Art

[0002] Soft rock is the most widely distributed rock in my country's strata. It is loose, dispersed, soft, and weak. Because its mineral composition includes clay minerals, the bearing capacity of soft rock will be greatly reduced when it comes into contact with water, and it may even undergo mud collapse. As my country's underground projects continue to advance deeper, the excavation of tunnels and other caverns is constrained by complex hydrogeological conditions. During the excavation of underground caverns, the impact of the groundwater seepage field on the surrounding rock anchoring structure is difficult to avoid. Under the influence of excavation disturbances, the surrounding rock will produce a large number of cracks and then connect to the overlying aquifer. Groundwater will invade the mining space through the surrounding rock cracks. If the surrounding rock is soft rock, it will seriously damage the stability of the surrounding rock roof anchoring structure, which is very likely to induce engineering geological disasters such as tunnel roof collapse. It will greatly increase the difficulty of cavern support and affect the safety of personnel. It has become a key bottleneck restricting the safe and efficient construction of underground projects.

[0003] Scholars have conducted extensive research on the erosion of soft rock cavern surrounding rock anchoring structures by fissure seepage water. However, existing studies have mostly focused on the effects of changes in water content and immersion time on the bearing capacity of soft rock anchoring structures, ignoring the impact of groundwater on the erosion rate and location of the anchoring structure. This means that the influence of fissure water seepage path and seepage volume has not been considered. Furthermore, in underground caverns, the tunnel roof anchoring body is exposed to the open air on one side, and groundwater from above penetrates the anchoring body through the fissures. However, current research often uses direct immersion, where the specimen is directly immersed in water. This method differs significantly from the actual groundwater seepage pattern and ignores the scouring effect of groundwater on the cement within the soft rock during the seepage of the roof anchoring structure, making the immersion results less reliable. Summary of the Invention

[0004] Purpose of the Invention: To address the above-mentioned issues, the present invention provides a device for simulating water seepage in soft rock cavern roof anchors, addressing the issues of existing water seepage testing methods that are inconsistent with actual conditions and result in poor reliability. A testing method is also provided.

[0005] Technical solution: A water seepage simulation device for anchor bodies in soft rock cavern roofs, including a water pump device, a water tank, a water seepage rack, and a sensor system;

[0006] The water tank, water pump device and seepage water rack are connected in sequence through water pipes;

[0007] The seepage water rack includes a seepage water simulation box and a perforated baffle. The perforated baffle is installed inside the seepage water simulation box to divide the inside of the seepage water simulation box into two spaces, the upper space is a water storage room, and the lower space is used to place anchored rock specimens.

[0008] The sensing system includes a water level controller and a water level sensor. The water level controller is installed on the water pump device, and the water level sensor is installed in the water storage room above the seepage water simulation box. The water level controller controls the operation of the water pump device through the seepage water rack water level signal transmitted by the water level sensor.

[0009] Furthermore, the seepage water rack also includes a lower baffle, a base, a top cover, and a support. The seepage water simulation box is installed on the base through the support. The top cover is installed on the top of the seepage water simulation box. Rectangular holes for installing the lower baffle are respectively provided on the opposite sides of the bottom of the seepage water simulation box. The water supply pipe is passed through the top cover to the water storage room.

[0010] The best, the seepage water simulation box is a hollow rectangular barrel structure, made of transparent PVC, with a wall thickness of 5 to 8 mm and a height of 260 to 280 mm. The length and width of the bottom of the seepage water simulation box are equal and are both 100 to 120 mm. Vertical threaded holes are respectively opened at the four top corners of the seepage water simulation box and the four corners of the top cover plate. The top cover plate is connected to the seepage water simulation box at the four threaded holes by bolts and nuts.

[0011] Optimally, the top cover is made of transparent PVC material with a length of 110-130 mm, a width of 110-130 mm, and a thickness of 5-8 mm; the lower baffle is made of transparent PVC material with a length of 120-140 mm, a width of 10-15 mm, and a thickness of 5-8 mm.

[0012] Furthermore, the perforated baffle is made of transparent PVC material, is horizontally clamped in the middle of the seepage water simulation box and is sealed to the inner wall of the seepage water simulation box through a sealing ring. The thickness of the perforated baffle is 30 to 40 mm, and there is at least one through drill hole on the perforated baffle, and the aperture of the drill hole is 1 to 1.5 mm.

[0013] Optimally, the number of drill holes is 1 to 10, the drill holes are inclined, and the inclination angles are 90°, 60°, 40°, and 30°. The horizontal distance between the center of the hole at the bottom of the drill hole and the axis of the anchor rod of the anchored rock specimen is 5mm, 10mm, 20mm, 30mm, and 40mm.

[0014] Furthermore, the water level sensor includes an upper water level sensor, a bottom water sensor, and a lower water level sensor, which are respectively installed at the upper, bottom, and lower parts of the water storage room and are respectively connected to the water level controller signal through water level sensor lines. The probe material of the upper water level sensor, the bottom water sensor, and the lower water level sensor are all made of 304 stainless steel.

[0015] Furthermore, the model of the water level controller is DF-96D fully automatic water level controller, and the operating voltage is 220V.

[0016] A test method for the above-mentioned soft rock cave roof anchor body water seepage simulation device comprises the following steps:

[0017] Step 1: Prepare anchored rock specimens to simulate the anchor body of the soft rock cave roof;

[0018] Step 2: Place the anchored rock specimen in the seepage water simulation box, and then install the perforated baffle and water level sensor in sequence;

[0019] Step 3: Turn on the power of the water pump device and fill the seepage water simulation box with water. The water level is automatically controlled by the water level controller. When water appears on the bottom of the seepage water simulation box and the surface of the anchored rock specimen, record the time t0. Then turn off the power of the water pump device and open the seepage water simulation box to pour out the water. Take out the anchored rock specimen and the perforated baffle, wipe off the moisture on the surface of the anchored rock specimen, and then cover its surface with plastic wrap whose water vapor transmission rate meets the national standard GB 10377-88.

[0020] Step 4: Replace perforated baffles of various sizes and repeat steps 2 and 3, setting the subsequent water seepage test time to t0. This will yield anchored rock specimens under different seepage paths and water volumes. Mechanical testing of the anchored rock specimens revealed the variation in the bearing capacity of anchored soft rock specimens under seepage conditions of various perforated baffle sizes. Response surface analysis was used to identify the dominant influencing factors among the three.

[0021] Optimally, in step 1, after obtaining the mudstone sample on site, it is prepared into a cubic sample of 100×100×100 mm, placed in a drying oven for drying, the temperature is set to 65°~70°C, and the drying time is 12~15 hours; after drying, an anchor hole is drilled in the center of one side of the rock sample and the anchor is installed, the drill hole diameter is 10~12 mm, and the depth is 80~85 mm; the anchor, tray, and nut are all made of 20MnSi steel, which is the same material as the mining threaded steel anchor, the anchor length is 90~95 mm, the diameter is 8~10 mm, the tray is 20~25 mm long, 20~25 mm wide, and 1~1.5 mm thick, the anchor agent is an epoxy resin with properties similar to the mining resin anchor agent, and the anchor bonding length is 40~45 mm.

[0022] Beneficial effects: Compared with the prior art, the advantages of the present invention are: (1) the immersion method of the anchor body during the test is closer to that in actual engineering, and the immersion results obtained are more accurate; (2) the water volume during the test is automatically adjusted by the water pump device and the water level controller, and no manual water addition is required; (3) by replacing the perforated baffle, different seepage paths and seepage volumes can be simulated; (4) the immersion results are helpful in revealing the hydration instability mechanism of the soft rock cave anchor structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a structural schematic diagram of the present invention;

[0024] Figure 2 It is a schematic diagram of the side section of the seepage water rack;

[0025] Figure 3 It is a structural diagram of the seepage water tank;

[0026] Figure 4 Schematic diagram of the structure of various specifications of perforated baffles. DETAILED DESCRIPTION

[0027] The present invention will be further described below with reference to the accompanying drawings and specific examples. It should be understood that these examples are only used to illustrate the present invention and are not used to limit the scope of the present invention.

[0028] A water seepage simulation device for soft rock cave roof anchor Figures 1 to 4 As shown, it includes a water pump device 1, a water tank 2, a seepage water rack, and a sensor system.

[0029] The water tank 2, the water pump device 1, and the seepage water rack are connected in sequence through the water pipe 7; the seepage water rack includes a seepage water simulation box 8, a lower baffle 9, a base 10, a top cover 11, a support 12, and a perforated baffle 13, as shown Figure 2 As shown. Figure 3 As shown, the seepage water simulation box 8 is in the shape of a hollow rectangular barrel, made of transparent PVC, with a wall thickness of 5mm, a height of 260mm, and an internal length and width of 100mm. Vertical threaded holes are drilled at the four corners of the top of the seepage water simulation box 8, and it is connected to the top cover plate by bolts and nuts. Two rectangular holes are drilled at the bottom of both sides for installing the lower baffle 9. The rectangular hole diameter is 10×5mm. The lower end of the rectangular hole is 5mm vertically away from the bottom of the seepage water box 8, and the outer side of the hole is 5mm horizontally away from the side of the seepage water box 8. The top cover 11 is made of transparent PVC, with vertical threaded holes drilled at the four corners. It is 110mm long, 110mm wide, and 5mm thick. The lower baffle 9 is made of transparent PVC, 120mm long, 10mm wide, and 5mm thick, and is used to prevent the anchored rock specimens from falling. There is a slot on the back of the seepage water simulation box 8 for connecting to the support 12. The support is L-shaped, made of 304 stainless steel, with a wall thickness of 5mm. The vertical portion is 280mm long, and the upper 160mm portion is inserted into the slot on the back of the water simulation box 8. The bottom horizontal portion is connected to the base 10 via bolts and nuts. The base 10 is square, made of 304 stainless steel, 5mm thick, and has a length and width of 130mm.

[0030] The perforated baffle 13 is installed inside the seepage water simulation box 8, dividing the inside of the seepage water simulation box 8 into two spaces, the upper space is the water storage room, and the lower space is used to place the anchored rock specimen 14. Figure 4As shown, the perforated baffle 13 is made of transparent PVC, 100 mm long, 100 mm wide, and 30 mm thick, with holes drilled inside. Different specifications (number of holes, drilling inclination, and drilling positions) of perforated baffles 13 are provided to simulate different numbers of cracks, crack inclinations, and crack distributions. By replacing the perforated baffles 13, different water seepage paths and water seepage amounts can be simulated. The diameter of the drill hole is 1 mm, the number of holes is set at 1 to 10, the drilling inclination is set at 90°, 60°, 40°, and 30° (the drilling inclination is the angle between the drilling axis and the horizontal plane), and the drilling position is set at 5 mm, 10 mm, 20 mm, 30 mm, and 40 mm. The drilling position refers to the horizontal distance between the center of the hole at the bottom of the drill hole and the axis of the anchor rod of the anchored specimen. There is a sealing ring on the side of the perforated baffle to prevent water from leaking from the side.

[0031] The sensing system includes a water level controller 3 and a water level sensor. The water level controller 3 is mounted on the water pump 1, and the water level sensor is installed in the water storage chamber above the seepage water simulation tank 8. The water level controller 3 controls the operation of the water pump 1 using the seepage water rack water level signal transmitted by the water level sensor. The water level sensor includes an upper water level sensor 4, a bottom water level sensor 5, and a lower water level sensor 6. These are installed in the upper, bottom, and lower parts of the water storage chamber, respectively, and are connected to the water level controller 3 via water level sensor cables. The probes of the upper water level sensor 4, bottom water level sensor 5, and lower water level sensor 6 are all made of 304 stainless steel. A through hole is provided in the top cover 11 to facilitate the passage of the water pipe 7 and the upper water level sensor 4, bottom water level sensor 5, and lower water level sensor 6.

[0032] The water level controller used was a DF-96D fully automatic water level controller with a 220V operating voltage. The water level sensor cable was 2m long, and the front probe was placed in the seepage water rack. The operating principle of the water pump device 1 is as follows: After the test begins, the power is turned on. When the water level in the seepage water simulation box 8 falls below the bottom of the water level lower limit sensor 6 probe, the water pump device 1 automatically fills the seepage water simulation box 8 with water. When the water level reaches the bottom of the water level upper limit sensor 4, the water pump device 1 automatically stops filling.

[0033] The experimental method of the soft rock cave roof anchor body water seepage simulation device comprises the following steps:

[0034] Step 1: Prepare anchored soft rock specimens 14 to simulate soft rock cave roof anchors. For example, after obtaining a mudstone sample from the site, a 100×100×100 mm cubic specimen was prepared and dried in a drying oven at 65°C for 12 hours. After drying, an anchor hole with a diameter of 10 mm and a depth of 80 mm was drilled in the center of one side of the sample and installed. The anchor, tray, and nut were all made of 20MnSi steel, the same material used for mining threaded steel anchors. The anchor was 90 mm long and 8 mm in diameter, while the tray was 20 mm long, 20 mm wide, and 1 mm thick. An epoxy resin with similar properties to mining resin anchors was used as the anchoring agent, and the anchor bond length was 40 mm.

[0035] Step 2: Insert the lower baffle 9 into the rectangular hole at the bottom of the seepage water simulation box 8, and then place the anchored soft rock specimen 14 (with the exposed surface of the anchor rod facing down) and the perforated baffle 13 (number of holes 10, drilling inclination 90°, drilling position 40mm) in sequence, and then install the top cover 11 on the top of the seepage water simulation box 8 with bolts and nuts, and drill holes along the inside of the top cover 11 to place the water level upper limit sensor 4, water bottom sensor 5, water level lower limit sensor 6, and water pipe 7.

[0036] Step 3: Turn on the power of the water pump device 1 and fill the seepage water simulation box 8 with water. The water level is automatically controlled by the water level controller 3. When water begins to drip onto the surface of the anchored soft rock specimen at the bottom of the seepage water simulation box, record the time t0. Then, turn off the power of the water pump device 1, remove the upper water level sensor 4, the bottom water sensor 5, the lower water level sensor 6, and the water pipe 7, and open the top cover 11 to drain the water from the seepage water simulation box 8. Then, remove the lower baffle 9, the anchored soft rock specimen 14, and the perforated baffle 13. Wipe off the moisture on the surface of the anchored soft rock specimen 14 and cover it with plastic wrap with a water vapor transmission rate that meets the national standard GB10377-88.

[0037] Step 4: Replace the perforated baffle 13 with a different one, then repeat steps 2 and 3, setting the subsequent water seepage test time to t0. This yields anchored soft rock specimens 14 under different seepage paths and water seepage rates. Mechanical testing of anchored soft rock specimens 14 reveals variations in their bearing capacity under conditions of varying drill hole numbers, drill hole inclinations, and drill hole locations. Response surface methodology is then used to analyze the dominant influencing factors among these three factors, helping to reveal the mechanisms by which groundwater seepage paths and water seepage rates influence the bearing capacity of the soft rock cavern roof anchoring structure.

Claims

1. A water seepage simulation device for a soft rock cave roof anchor, characterized by: It comprises a water pump device (1), a water tank (2), a seepage water rack, and a sensor system; The water tank (2), the water pump device (1), and the seepage water rack are connected in sequence through a water pipe (7); The seepage water rack comprises a seepage water simulation box (8) and a perforated baffle (13). The perforated baffle (13) is installed inside the seepage water simulation box (8) to divide the inside of the seepage water simulation box (8) into two spaces, the upper space being a water storage room and the lower space being a place for placing an anchored rock specimen (14). The sensing system comprises a water level controller (3) and a water level sensor. The water level controller (3) is installed on the water pump device (1). The water level sensor is installed in a water storage room above the seepage water simulation box (8). The water level controller (3) controls the operation of the water pump device (1) through a seepage water frame water level signal transmitted by the water level sensor.

2. The soft rock cave roof anchor water seepage simulation device according to claim 1, characterized in that: The seepage water frame further comprises a lower baffle (9), a base (10), a top cover (11), and a support (12); the seepage water simulation box (8) is mounted on the base (10) via the support (12); the top cover (11) is mounted on the top of the seepage water simulation box (8); rectangular holes for mounting the lower baffle (9) are respectively provided on opposite sides of the bottom of the seepage water simulation box (8); and a water delivery pipe (7) is passed through the top cover (11) to the water storage room.

3. The soft rock cave roof anchor water seepage simulation device according to claim 2, characterized in that: The seepage water simulation box (8) is a hollow rectangular barrel-shaped structure made of transparent PVC. The wall thickness of the seepage water simulation box (8) is 5-8 mm, the height is 260-280 mm, and the length and width of the bottom surface of the seepage water simulation box (8) are equal and both are 100-120 mm. Vertical threaded holes are respectively opened at the four top corners of the seepage water simulation box (8) and the four corners of the top cover (11). The top cover (11) is connected to the seepage water simulation box (8) through bolts and nuts at the four threaded holes.

4. The soft rock cave roof anchor water seepage simulation device according to claim 2, characterized in that: The top cover plate (11) is made of transparent PVC material, with a length of 110-130 mm, a width of 110-130 mm, and a thickness of 5-8 mm; the lower baffle plate (9) is made of transparent PVC material, with a length of 120-140 mm, a width of 10-15 mm, and a thickness of 5-8 mm.

5. The device for simulating water seepage of a soft rock cave roof anchor according to claim 1, characterized in that: The perforated baffle (13) is made of transparent PVC material, is horizontally clamped in the middle of the seepage water simulation box (8), and is sealed with the inner peripheral wall of the seepage water simulation box (8) through a sealing ring. The thickness of the perforated baffle (13) is 30 to 40 mm. At least one through-hole is opened on the perforated baffle (13), and the hole diameter of the hole is 1 to 1.5 mm.

6. The soft rock cave roof anchor water seepage simulation device according to claim 5, characterized in that: The number of the drill holes is 1 to 10, the drill holes are opened at an inclination angle of 90°, 60°, 40°, and 30°, and the horizontal distance between the center of the hole at the bottom of the drill hole and the axis of the anchor rod of the anchored rock specimen (14) is 5 mm, 10 mm, 20 mm, 30 mm, and 40 mm.

7. The device for simulating water seepage of a soft rock cave roof anchor according to claim 1, characterized in that: The water level sensor comprises an upper water level sensor (4), a bottom water sensor (5), and a lower water level sensor (6), which are respectively installed at the upper part, the bottom part, and the lower part of the water storage room and are respectively connected to the water level controller (3) via water level sensor lines. The probes of the upper water level sensor (4), the bottom water sensor (5), and the lower water level sensor (6) are all made of 304 stainless steel.

8. The device for simulating water seepage of a soft rock cave roof anchor according to claim 1, characterized in that: The model of the water level controller (3) is DF-96D fully automatic water level controller, and the operating voltage is 220V.

9. A test method for the water seepage simulation device for soft rock cave roof anchors according to any one of claims 1 to 8, characterized in that The following steps are involved: Step 1: preparing an anchored rock specimen (14) to simulate a soft rock cave roof anchor; Step 2: After placing the anchored rock specimen (14) in the seepage water simulation box (8), the perforated baffle (13) and the water level sensor are installed in sequence; Step 3: Turn on the power of the water pump device (1) and inject water into the seepage water simulation box (8), and the water level is automatically controlled by the water level controller (3); wait until water appears on the bottom of the seepage water simulation box (8) and the surface of the anchored rock specimen (14), record the time t0, then turn off the power of the water pump device (1), open the seepage water simulation box (8) and pour out the water therein; take out the anchored rock specimen (14) and the perforated baffle (13), wipe off the moisture on the surface of the anchored rock specimen (14), and then cover its surface with a plastic wrap whose water vapor permeability meets the national standard GB10377-88; Step 4: Replace the perforated baffles (13) of various specifications, repeat steps 2 and 3 in sequence, and set the subsequent water seepage test time to t0, so as to obtain anchored rock specimens (14) under different water seepage paths and water seepage conditions. By conducting mechanical tests on the anchored rock specimens (14), the change law of the bearing performance of the anchored soft rock specimens under the seepage of the perforated baffles (13) of various specifications is obtained, and the dominant influencing factors among the three are obtained by using the response surface method.

10. The test method of the soft rock cave roof anchor water seepage simulation device according to claim 9, characterized in that: In step 1, after obtaining the mudstone sample on site, it is prepared into a cubic sample of 100×100×100 mm, placed in a drying oven for drying, the temperature is set to 65°~70℃, and the drying time is 12~15 hours; after drying, an anchor hole is drilled in the center of one side of the rock sample and the anchor is installed, the drill hole diameter is 10~12 mm, and the depth is 80~85 mm; the anchor rod, tray, and nut are all made of 20MnSi steel, which is the same material as the mining threaded steel anchor rod. The anchor rod length is 90~95 mm, the diameter is 8~10 mm, the tray length is 20~25 mm, the width is 20~25 mm, and the thickness is 1~1.5 mm. The anchor agent is an epoxy resin with similar properties to the mining resin anchor agent, and the anchor rod bonding length is 40~45 mm.

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