Grouting model test system and method under water-rock interaction of karst tunnel

Abstract

The invention discloses a grouting model test system and method under karst tunnel water-rock interaction, and belongs to the field of grouting construction simulation.The system comprises a test workbench, an extension supporting frame is arranged on one side of the test workbench, a rotating support is rotationally arranged in a lifting frame on one side of the extension supporting frame, and a mold frame is arranged at the top of the rotating support; a grouting groove body is formed in a karst module in the mold frame, and solidified slurry can be taken out along with splitting of the module; the first driving assembly drives the lifting frame to enable the mold frame to be immersed in water to detect the sealing performance; the grouting pump conveys slurry in the slurry storage barrel to the grouting groove body, and the booster water pump forms water circulation through the drainage pipeline to simulate karst seepage; the second driving assembly drives the mold frame to rotate to change the grouting flow direction; the system can simulate the grouting and water-rock action under different working conditions to solve the problems that when a traditional grouting model test device is used for rock mass simulation, module installation is tedious, solidified slurry is difficult to take out, angle adjustment is limited, and the grouting simulation effect is poor.

Description

Technical Field

[0001] This invention belongs to the field of grouting construction simulation technology, and relates to a grouting model test system and method under the interaction of water and rock in karst tunnels. Background Technology

[0002] When constructing tunnels in karst areas, the interaction between water and rock can easily trigger geological disasters such as water inrush and collapse. Grouting technology is a key means to prevent such disasters. By studying the diffusion law of grout in karst fissures, its solidification properties, and its interaction with water flow through grouting model tests, important basis can be provided for the design of actual construction parameters. Therefore, the development of related test systems has always been a focus of attention in the engineering field.

[0003] Currently, existing grouting model test devices have many limitations in practical applications. In the test preparation stage, the installation of rock mass simulation modules of most devices is cumbersome, requiring multiple adjustments to the positioning to ensure sealing. Moreover, most modules are integral structures, making it difficult to completely remove the solidified grout after the test, resulting in missing grout performance test data.

[0004] Meanwhile, traditional grouting model test devices have limited angle adjustment functions, making it difficult to simulate different grouting angles during tunnel construction, and the test scenarios are limited. Summary of the Invention

[0005] In view of this, in order to solve the problems of cumbersome module installation, difficulty in removing solidified grout and limited angle adjustment, resulting in poor grouting simulation effect when using the above-mentioned traditional grouting model test device for rock mass simulation, the present invention provides a grouting model test system and method for water-rock interaction in karst tunnels.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A grouting model test system for water-rock interaction in karst tunnels includes a test workbench, which is shaped like a pool. An extension support frame is fixed to the top of one side of the test workbench. A lifting frame is installed on one side of the extension support frame, and a rotating bracket is rotatably installed inside the lifting frame. A mold frame is adjustablely installed on the top of the rotating bracket.

[0008] The mold frame includes an outer frame and a top cover plate. Multiple karst modules are set inside the outer frame. Multiple grouting tanks are opened on the karst modules. After solidification, the grout can be taken out from the grouting tanks along with the karst modules.

[0009] The first drive assembly is located on one side of the extension support frame and is used to drive the lifting frame to rise and fall, so that the mold frame is submerged in the water of the test workbench to test the sealing performance.

[0010] The grouting pump is fixed on one side of the test workbench, and a grout storage tank is provided on one side of the test workbench. The inlet end of the grouting pump extends into the grout storage tank through a pipe, and the outlet end is connected to the mold frame through a pipe. The grout is transported to the grouting tank by the grouting pump.

[0011] The booster pump is fixed on one side of the test bench. The bottom of the test bench is equipped with a drainage pipe. The drainage pipe is in the shape of a tee, with a valve at one end and the other two ends connected to the inside of the test bench and the water inlet of the booster pump, respectively. The drain end of the booster pump is connected to the mold frame. The water flows through the booster pump to simulate karst seepage.

[0012] The second drive component is mounted on the lifting frame and is used to drive the mold frame to rotate in order to change the direction of grout flow.

[0013] The top of the extended support frame is fixed with a top load-bearing frame, and the bottom of the top load-bearing frame is fixed with a camera mounting bracket. Multiple cameras are installed in the camera mounting bracket for filming the grouting and water flow process.

[0014] As a further improvement to the above technical solution:

[0015] Two rotating bases are fixed on one side of the outer frame. A connecting bracket is rotatably installed inside the rotating base. Two guide optical shafts are slidably installed through the top of the connecting bracket. The bottom of the two guide optical shafts is fixed to the same connecting base. The connecting base is connected to the top cover plate.

[0016] A transmission screw II is threaded through the top of the connecting bracket. The bottom end of the transmission screw II is rotatably connected to the connecting base. Rotating the transmission screw II can drive the top cover plate to rise and fall.

[0017] A limiting bolt with a through thread is provided on one side of the rotating base to abut against the connecting bracket and to fix the position of the connecting bracket.

[0018] As a further improvement to the above technical solution:

[0019] The lifting frame includes two sliding guide frames that are slidably set on both sides of the extension support frame. Multiple support columns are fixed between the two sliding guide frames, and the positions of the support columns avoid the rotation trajectory of the mold frame.

[0020] The rotating bracket is rotatably positioned between two sliding guide frames, and the supporting column is used to enhance the stability of the sliding guide frames.

[0021] As a further improvement to the above technical solution:

[0022] The first drive assembly includes a ball screw I that is rotatably mounted inside the test workbench. A screw nut is fitted on the outer wall of the ball screw I, and balls inside the screw nut roll in the thread groove of the ball screw I.

[0023] A fixed base I is fixedly connected to the outer wall of the screw nut. The fixed base I is fixedly sleeved on the support column. A drive motor I is fixed on one side of the test workbench. The output end of the drive motor I is connected to the ball screw I through a synchronous pulley and a synchronous belt to drive the lifting frame to rise and fall.

[0024] As a further improvement to the above technical solution:

[0025] The rotating support includes a rotating main shaft that is rotatably mounted on one side of the sliding guide frame. A fixed base II is fixedly sleeved on the outer wall of one end of the rotating main shaft, and the same supporting rib is fixed between the two fixed bases II.

[0026] The mold frame is mounted on the supporting ribs, and the rotation of the main shaft can drive the mold frame to rotate synchronously.

[0027] As a further improvement to the above technical solution:

[0028] The second drive assembly includes a drive motor II fixed on one side of the sliding guide frame, a rotary transmission shaft rotatably mounted on one side of the sliding guide frame, and the output end of the drive motor II connected to the rotary transmission shaft via a flexible coupling.

[0029] Both the outer wall of the other end of the rotating spindle and the other end of the rotating transmission shaft are fixedly fitted with meshing transmission gears. The operation of the drive motor II can drive the rotating spindle to rotate through gear transmission.

[0030] As a further improvement to the above technical solution:

[0031] The outer wall of the supporting rib is adjustable with an adjustment base, and an electric push rod is rotatably mounted on the top of the adjustment base. The top of the electric push rod is rotatably connected to the bottom of the outer frame.

[0032] The electric push rod can extend and retract to adjust the tilt angle of the mold frame, and work with the rotating bracket to achieve multi-angle simulation.

[0033] As a further improvement to the above technical solution:

[0034] Two sets of partition plates are fixed inside the outer frame. A buffer trough is formed between the partition plates and the outer frame. Water flows through the buffer trough and then flows through the karst module.

[0035] The karst module is bilobed and located between two sets of partition plates, with a sealing rubber plate between adjacent karst modules;

[0036] A drainage control valve is connected to one side of the outer frame, and a discharge trough is provided between each set of partition plates to discharge excess slurry.

[0037] As a further improvement to the above technical solution:

[0038] A displacement gap is reserved between the karst module and the outer frame. Under the action of water flow or slurry pressure, the karst module can generate a small displacement along the displacement gap to simulate the stress deformation of the surrounding rock.

[0039] A grouting model test method for karst tunnel water-rock interaction, employing the aforementioned grouting model test system for karst tunnel water-rock interaction, includes the following steps:

[0040] S1. Place the karst module into the outer frame, adjust the top cover seal through the transmission screw II, and inject water into the test workbench;

[0041] S2. The mold frame is submerged in water using the first drive component to check the sealing performance. If no air bubbles are found, the test is complete.

[0042] S3. Adjust the second drive assembly and electric push rod to the preset angle, and start the camera to take pictures;

[0043] S4. Start the grouting pump to inject grout into the grouting tank, and at the same time start the booster water pump to circulate the water and simulate the water-rock action.

[0044] S5. After grouting is completed, let it stand until the grout solidifies, then disassemble the karst module, remove the grout for testing, and clean the equipment.

[0045] The beneficial effects of this invention are as follows:

[0046] 1. The grouting model test system for water-rock interaction in karst tunnels disclosed in this invention uses 3D printing to fabricate karst modules. The surface grouting tank can reproduce the actual rock mass fracture morphology. The two-lobed structure combined with the sealing rubber plate ensures both simulation sealing and allows for complete removal of the solidified grout after the test. The buffer tank can reduce the direct impact of water flow on the karst module. The displacement gap allows the module to produce small displacements under pressure. Combined with adjustable water flow velocity and grouting pressure, it can realistically reproduce water-rock interaction and grouting scenarios under different working conditions, providing a realistic basic environment for the test.

[0047] 2. The grouting model test system for water-rock interaction in karst tunnels disclosed in this invention can smoothly control the lifting and lowering of the mold frame through the first drive component to achieve sealing test; the second drive component, in conjunction with the electric push rod, can adjust the angle of the mold frame within the range of 0-150° to simulate the grouting state of different construction positions.

[0048] 3. The grouting model test system for water-rock interaction in karst tunnels disclosed in this invention adopts a standardized design for the karst module, which can be quickly installed by docking through slots without the need for complex positioning procedures. The top cover plate can be quickly raised and lowered through the transmission screw II and the guide optical shaft. The sealing adjustment can be completed by simply rotating the screw. Moreover, there is no need to frequently stop the machine for adjustment during a single test. It can continuously complete the grouting, water flow action and solidification monitoring stages.

[0049] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0050] To make the objectives, technical solutions, and advantages of the present invention clearer, the preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein:

[0051] Figure 1 This is a schematic diagram of the grouting model test system for karst tunnel water-rock interaction according to the present invention. Figure 1 ;

[0052] Figure 2 This is a schematic diagram of the grouting model test system for karst tunnel water-rock interaction according to the present invention. Figure 2 ;

[0053] Figure 3 This is a schematic diagram of the lifting frame structure in this invention;

[0054] Figure 4 This is a schematic diagram of the installation of the connecting bracket in this invention;

[0055] Figure 5 This is a schematic diagram of the lifting frame structure in this invention;

[0056] Figure 6 This is a schematic diagram of a partial structure of the mold frame in this invention;

[0057] Figure 7 This is a schematic diagram of the installation structure of the mold frame and karst module in this invention.

[0058] Reference numerals: 1. Test workbench; 2. Extension support frame; 3. Top load-bearing frame; 4. Camera mounting bracket; 5. Lifting frame; 51. Sliding guide frame; 52. Support column; 53. Ball screw I; 54. Fixed base I; 55. Screw nut; 56. Drive motor I; 6. Mold frame; 61. Outer frame; 62. Top cover plate; 63. Drain control valve; 64. Rotating base; 65. Connecting bracket; 66. Limit bolt; 67. Guide optical axis; 68. Connecting base; 69. Transmission... 7. Moving screw II; 71. Rotating bracket; 72. Rotating spindle; 73. Fixed base II; 74. Support rib; 75. Adjusting base; 76. Drive motor II; 77. Flexible coupling; 78. Rotary transmission shaft; 79. Transmission gear; 80. Electric push rod; 91. Booster water pump; 10. Grouting pump; 11. Grout storage tank; 12. Drainage pipe; 13. Karst module; 14. Grouting tank; 15. Sealing rubber plate; 16. Divider plate; 17. Buffer tank; 18. Discharge tank; 19. Displacement clearance. Detailed Implementation

[0059] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0060] like Figures 1-2 The grouting model test system for karst tunnel water-rock interaction shown herein has a test workbench 1 made of 304 stainless steel, shaped like a pool, with a welded steel plate at the bottom for reinforcement. An extension support frame 2 is fixed to the top of one side of the test workbench 1 using M12 bolts. The extension support frame 2 is constructed of aluminum alloy profiles, connected by angle brackets and bolts. Two parallel slide rails are installed inside the extension support frame 2, with the same height as the extension support frame 2. A lifting frame 5 is connected to the slide rails via a slider. Lubricant is applied between the slider and the slide rails to allow the lifting frame 5 to move smoothly up and down along the slide rails without significant shaking during movement. A rotating bracket 7 is installed inside the lifting frame 5, and a mold frame 6 is connected to the top of the rotating bracket 7. The mold frame 6 rotates with the rotating bracket 7. Multiple control switches and a power distribution cabinet are also located on one side of the test workbench 1 for controlling the start and stop of electrical components.

[0061] like Figure 6 , 7As shown, the mold frame 6 includes an outer frame 61 and a top cover plate 62. The outer frame 61 is made of aluminum alloy plate folded and welded to form a sealed space. The top cover plate 62 is made of transparent acrylic plate, with a 10 mm wide rubber sealing ring pasted on the edge. When closed, the sealing ring can fit tightly with the top edge of the outer frame 61, ensuring both airtightness and easy observation of the internal situation. Multiple karst modules 12 are placed inside the outer frame 61. The karst modules 12 are made of photosensitive resin through 3D printing, and have a two-lobed structure that can be connected via slots. Multiple grouting grooves 13 are printed on the surface of the karst modules 12 according to the geological survey data of the actual karst tunnel. The solidified grout can completely fill the grouting grooves 13. After disassembling the karst module 12, the solidified grout can be directly removed.

[0062] like Figure 3 As shown, the lifting frame 5 includes two sliding guide frames 51, which are cut from steel plates with a thickness of 8 mm and connected to the slide rail of the extension support frame 2 via sliders. Three support columns 52 are welded between the two sliding guide frames 51. The support columns 52 are round steel with a diameter of 30 mm and a length equal to the distance between the two sliding guide frames 51. The positions of the three support columns 52 avoid the trajectory of the mold frame 6 during rotation, ensuring that the mold frame 6 does not collide with the support columns 52 during rotation.

[0063] The first drive assembly is installed on one side of the extension support frame 2 to drive the lifting frame 5 to rise and fall. The ball screw I 53 in this assembly is a trapezoidal screw, with a length equal to the height of the extension support frame 2. Both ends are fixed inside the test workbench 1 via bearing seats. The bearing seats are connected to the reinforcing ribs at the bottom of the test workbench 1 and the top of the extension support frame 2 via bolts. A screw nut 55 is fitted onto the outer wall of the ball screw I 53. The balls inside the screw nut 55 match the thread grooves of the ball screw I 53, and the balls are separated by a retainer to reduce friction during transmission. A fixed base I 54 is welded to the outer wall of the screw nut 55. The other side of the fixed base I 54 is connected to the lifting frame 5 via bolts, and rubber pads are added to the connection point to reduce vibration transmission. Figure 5As shown, a drive motor I56, a servo motor, is fixed to one side of the test bench 1 via a bracket. A synchronous pulley is mounted on the output end of the drive motor I56. A synchronous pulley of the same specification is also mounted on the end of the ball screw I53 near the drive motor I56. The two synchronous pulleys are connected by a polyurethane synchronous belt, the tension of which can be adjusted by adjusting the installation position of the drive motor I56. When the drive motor I56 is started, the synchronous belt drives the ball screw I53 to rotate, and the screw nut 55 moves along the axial direction of the ball screw I53, thereby driving the lifting frame 5 to move up and down. When it is necessary to test the sealing performance of the mold frame 6, the lifting frame 5 is lowered, completely immersing the mold frame 6 in the water within the test bench 1. This is maintained for 15 minutes. If no bubbles continuously emerge from the water surface, it indicates that the sealing performance of the mold frame 6 meets the test requirements.

[0064] A grouting pump 9 is fixed to the side of the test workbench 1 near the extension support frame 2 via an angle steel bracket. The angle steel bracket is bolted to the test workbench 1. The grouting pump 9 is a plunger-type grouting pump, and a rubber pad is placed between the pump body and the bracket to reduce vibration and noise during operation. A slurry storage tank 10 is placed on one side of the test workbench 1. The slurry storage tank 10 is made of polyethylene, and a filter screen with a 2 mm aperture is installed at the opening of the tank to prevent impurities in the slurry from entering the grouting pump 9. A pressure-resistant hose is connected to the inlet end of the grouting pump 9. One end of the hose passes through the lid of the slurry storage tank 10 and extends to the bottom of the tank. The other end is connected to the inlet of the grouting pump 9 via a clamp. The outlet end is also connected to the inlet of the mold frame 6 via a pressure-resistant hose. The hose can withstand a pressure of 6 MPa to prevent bursting during grouting. A booster water pump 8, a centrifugal water pump, is fixed to the lower side of the test workbench 1 via bolts. A drainage pipe 11 is welded to the bottom of the test workbench 1. The drainage pipe 11 is a stainless steel pipe in the shape of a tee. One end is equipped with a ball valve as a valve, the other end is connected to the inside of the test workbench 1, and the remaining end is connected to the inlet of the booster water pump 8 through a hose. The outlet of the booster water pump 8 is connected to the inlet of the mold frame 6 through a hose, and the outlet of the mold frame 6 flows back into the test workbench 1 through a pipe, forming a closed water circulation system to simulate the water flow in karst.

[0065] The second drive assembly is mounted on the lifting frame 5 and is used to drive the mold frame 6 to rotate. The rotating bracket 7 is rotatably mounted between two sliding guide frames 51 via two bearings, with the bearing seats fixed to the sliding guide frames 51. The rotating main shaft 71 in the rotating bracket 7 is a hollow round shaft made of No. 45 steel, with both ends connected to the mold frame 6 and the pump body respectively via rotary joints. The rotating main shaft 71 rotates through bearing holes in the sliding guide frames 51. A fixed base II 72 is welded to the outer wall of one end of the rotating main shaft 71. The fixed base II 72 is a square cut from a steel plate. Supporting ribs 73 are welded between the two fixed bases II 72. The supporting ribs 73 are square steel, with a length equal to the distance between the two fixed bases II 72. The drive motor II 75 in the second drive assembly is fixed to the outside of the sliding guide frame 51 by bolts. The drive motor II 75 is a stepper motor. A rotating transmission shaft 77 is mounted on the side of the sliding guide frame 51 corresponding to the drive motor II 75 via a bearing seat, with an interference fit to the bearing inside the bearing seat. The output end of drive motor II 75 is connected to rotary transmission shaft 77 via flexible coupling 76. Both the outer wall of the rotary main shaft 71 away from the fixed base II 72 and the end of the rotary transmission shaft 77 away from the flexible coupling 76 are fixedly fitted with transmission gears 78, which mesh with each other. When drive motor II 75 is started, rotary transmission shaft 77 drives rotary main shaft 71 to rotate via transmission gears 78, thereby driving mold frame 6 to rotate. The rotation angle can be adjusted arbitrarily between 0-150°, thus changing the grout flow direction and simulating grouting in different directions during tunnel construction.

[0066] The outer wall of the supporting rib 73 has an elongated hole. The adjusting base 74 is installed in the elongated hole by bolts of M10 specification. After loosening the bolts, the adjusting base 74 can move back and forth along the elongated hole. After adjustment, tightening the bolts will fix it. The top of the adjusting base 74 is connected to the electric push rod 79 by a pin. The top of the electric push rod 79 is also connected to the bottom of the outer frame 61 by a pin. By extending and retracting, the tilt angle of the mold frame 6 can be changed. In conjunction with the rotation of the rotating bracket 7, the angle adjustment of the mold frame 6 can be made more flexible.

[0067] The top of the extension support frame 2 is welded to a top load-bearing frame 3. The top load-bearing frame 3 is constructed of aluminum alloy square tubing and has a rectangular structure. A camera mounting bracket 4 is bolted to the bottom of the top load-bearing frame 3. The camera mounting bracket 4 is a box-shaped structure made of bent steel plate with multiple mounting holes (the mounting holes are used to connect to the top load-bearing frame 3 via bolts, and...) Figure 1 The mounting holes on the camera mounting bracket 4 are located below the top support frame 3. The camera mounting bracket 4 is equipped with 3 industrial cameras, which can cover the upper surface of the mold frame 6 and capture real-time images of the flow and diffusion of grout during the grouting process, as well as the interaction between water flow and grout. The captured images are transmitted to a computer for storage via a data cable.

[0068] like Figure 4 As shown, two rotating bases 64 are welded to one side of the outer frame 61. Each rotating base 64 consists of two parallel steel plates connected to a connecting bracket 65 via pins. The connecting bracket 65 can rotate freely around the pins. The connecting bracket 65 is made of bent and welded steel, with two through holes at the top through which two guide shafts 67 pass. The guide shafts 67 are chrome-plated with a surface roughness of Ra0.8, and limit plates are fixed at both ends with nuts to prevent them from falling out of the through holes. A common connecting base 68 is welded to the bottom of the two guide shafts 67. The connecting base 68 is a steel plate connected to the top cover plate 62 via multiple universal joints at the bottom. A threaded hole is located at the center of the top of the connecting bracket 65, through which a transmission screw II 69 passes. The bottom end of the transmission screw II 69 is connected to the connecting base 68 via a deep groove ball bearing. The inner ring of the bearing is interference-fitted with the transmission screw II 69, while the outer ring is transition-fitted with the mounting hole of the connecting base 68. When the transmission screw II 69 is rotated, the connecting base 68 moves up and down along the guide optical axis 67, causing the top cover plate 62 to rise and fall, thereby adjusting the sealing force between the top cover plate 62 and the outer frame 61. A threaded hole is opened on one side of the rotating base 64, through which the limiting bolt 66 passes. Rotating the limiting bolt 66 so that its end abuts against the connecting bracket 65 can fix the rotating connecting bracket 65 to the rotating base 64 after rotational adjustment.

[0069] Two sets of partition plates 15 are welded inside the outer frame 61. Each set of partition plates 15 consists of two parallel acrylic sheets, which fit snugly against the inner wall of the outer frame 61, forming a buffer trough 16. Karst modules 12 are placed between the two sets of partition plates 15. A sealing rubber plate 14 is sandwiched between adjacent karst modules 12. The sealing rubber plate 14 is made of nitrile rubber with a mesh-like texture on its surface, which enhances the friction between the karst modules 12 and also acts as a seal to prevent grout leakage from the gaps between the modules. A drainage control valve 63, a ball valve, is connected to one side of the outer frame 61 via a pipe. The opening of the drainage control valve 63 can be adjusted by rotating the handle to control the drainage speed. A discharge trough 17 is provided between each set of partition plates 15, allowing grout to enter and exit through the discharge trough 17 during grouting, ensuring that the grout fills the grouting tank 13.

[0070] A displacement gap 18 is reserved between the karst module 12 and the outer frame 61. When water flow or slurry exerts pressure on the karst module 12, the karst module 12 is allowed to have a small displacement. The displacement can be recorded and compared by taking pictures with a camera before installation and after solidification and removal to simulate the deformation state of the actual surrounding rock after being subjected to force.

[0071] When using the grouting model test system for karst tunnel water-rock interaction, select a matching karst module 12 according to the test requirements and place it inside the outer frame 61. Place sealing rubber plates 14 between adjacent karst modules 12 to ensure tight fit between the modules. Connect the industrial camera on the camera mounting bracket 4 to the computer, adjust the shooting angle to ensure clear imaging of the front of the mold frame 6, and take pictures to record the position of the karst module 12 after each placement. Move the connecting bracket 65 to move the top cover plate 62 above the outer frame 61, and rotate the limiting bolt 66 so that one end of the limiting bolt 66 abuts against the connecting bracket 65. Rotate the transmission screw II 69 to drive the connecting base 68 and the top cover plate 62 to descend, so that the rubber sealing ring at the edge of the top cover plate 62 fits against the top of the outer frame 61, completing the assembly of the mold frame 6. Pour the grout prepared according to the preset ratio into the grout storage tank 10, such as cement-water glass grout mixed at a volume ratio of 2:1, stir evenly, let stand for 5 minutes, and then filter through a filter screen for later use.

[0072] Fill the test bench 1 with clean water, maintaining a depth of approximately 0.5 meters. Start the drive motor I56, which drives the ball screw I53 to rotate via the synchronous pulley and belt. The screw nut 55 moves along the ball screw I53, pushing the lifting frame 5 down along the slide rail until the mold frame 6 is completely submerged in water. Turn off the drive motor I56 and simultaneously start the booster pump 8 to pump water from the test bench 1 into the mold frame 6 until the set pressure is reached. Maintain this state for 15 minutes, observing through the top cover 62 for any air bubbles generated inside the mold frame 6, and simultaneously observing for any continuous air bubbles rising from the water surface of the test bench 1. If no air bubbles are present, reverse the drive motor I56 to raise the lifting frame 5 to the initial position, completing the sealing test. If air bubbles are present, check the sealing of the karst module 12 connection and the top cover 62, adjust accordingly, and retest.

[0073] Adjust the angle of mold frame 6 according to the test plan, start drive motor II 75, drive the rotary transmission shaft 77 to rotate through the flexible coupling 76, and the transmission gear 78 meshes to drive the rotary main shaft 71 to rotate the rotary support 7, rotate the mold frame 6 to the preset angle, turn off drive motor II 75, start electric push rod 79 to extend and retract, so that the tilt angle of mold frame 6 reaches the test requirements, such as 15°, and turn off electric push rod 79. Turn on camera recording function for subsequent observation of slurry flow.

[0074] Open the valves at the inlet and outlet of the grouting pump 9, start the grouting pump 9, and adjust the pressure to a preset value, such as 1.5 MPa. The grout enters the mold frame 6 through the pressure-resistant hose and fills the simulated fissures of the karst module 12 through the grouting tank 13. At the same time, start the booster water pump 8, open the drain control valve 63, and the water flows into the mold frame 6 through the drain pipe 11. After being buffered by the buffer tank 16, the water flows over the surface of the karst module 12 and is discharged through the drain control valve 63 under the pressure of the grout. During the grouting process, the diffusion of the grout in the grouting tank 13 is observed in real time by a camera, and the grout filling time and the convection state of the water flow on the grout are recorded.

[0075] Grouting is complete when the grout is discharged from the drainage control valve 63. Then, shut off the grouting pump 9 and related valves. Continue running the booster pump 8 for 30 minutes to simulate the effect of water flow on the initially set grout. Afterward, shut off the booster pump 8 and the drainage pipe 11 valves. Allow the grout to stand until completely solidified, or for cement-based grout, cure for 7 days, maintaining the test environment temperature at 20-25℃. After solidification, reverse the rotation of the drive screw II 69 to open the top cover 62, separate the karst module 12 at the joint, remove the solidified grout from the grouting tank 13, clean off any surface impurities, and place it in a drying oven to dry at 60℃ to constant weight for subsequent testing of compressive strength, permeability coefficient, and other indicators.

[0076] Clean the residual grout inside the mold frame 6, rinse the karst module 12 and outer frame 61 with clean water, and ensure that the grouting tank 13 and discharge tank 17 are unobstructed. Adjust the lifting frame 5, rotating bracket 7 and mold frame 6 to their initial positions, turn off the power to all equipment and disconnect the wiring. Clean the remaining grout in the grout storage tank 10, rinse the pressure hose and pipes with clean water and let them dry, and store all parts according to the storage requirements.

[0077] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A grouting model test system for karst tunnel water-rock interaction, characterized in that, The test workbench (1) is shaped like a pool. An extension support frame (2) with a lifting frame (5) is fixed on the top of the test workbench (1). A rotating bracket (7) is rotatably installed inside the lifting frame (5). A mold frame (6) is adjustable on the top of the rotating bracket (7). The mold frame (6) includes an outer frame (61) and a top cover plate (62). Multiple karst modules (12) are provided inside the outer frame (61). Multiple grouting tanks (13) are opened on the karst modules (12). After solidification, the grout can be taken out from the grouting tanks (13) along with the karst modules (12). The first drive assembly is located on one side of the extension support frame (2) and is used to drive the lifting frame (5) to rise and fall, so that the mold frame (6) is submerged in the water of the test workbench (1) to test the sealing performance. The grouting pump (9) and the grout storage tank (10) are fixed on the back side of the test workbench (1). The inlet end of the grouting pump (9) extends into the grout storage tank (10) through a pipe, and the outlet end is connected to the mold frame (6) through a pipe. The grout is transported to the grouting tank (13) by the grouting pump (9). The booster pump (8) is also fixed on the back side of the test workbench (1). The bottom of the test workbench (1) is provided with a drainage pipe (11). The drainage pipe (11) is in the shape of a three-way valve. One end is equipped with a valve, and the other two ends are connected to the inside of the test workbench (1) and the water inlet of the booster pump (8). The drain end of the booster pump (8) is connected to the mold frame (6). The water flows through the booster pump (8) to circulate and simulate karst seepage. The second drive assembly is set on the lifting frame (5) and is used to drive the mold frame (6) to rotate to change the grouting flow direction; The top of the extension support frame (2) is fixed with a top load-bearing frame (3), and the bottom of the top load-bearing frame (3) is fixed with a camera mounting frame (4). Multiple cameras are installed inside the camera mounting frame (4) for filming the grouting and water flow process.

2. The grouting model test system for karst tunnel water-rock interaction according to claim 1, characterized in that, Two rotating bases (64) are fixed on one side of the outer frame (61). A connecting bracket (65) is rotatably arranged inside the rotating base (64). Two guide optical shafts (67) are slidably arranged through the top of the connecting bracket (65). The bottom of the two guide optical shafts (67) is fixed with the same connecting base (68). The connecting base (68) is connected to the top cover plate (62). A transmission screw II (69) is threaded through the top of the connecting bracket (65). The bottom end of the transmission screw II (69) is rotatably connected to the connecting base (68). Rotating the transmission screw II (69) can drive the top cover plate (62) to rise and fall. A limiting bolt (66) that abuts against the connecting bracket (65) is threaded through one side of the rotating base (64) to fix the position of the connecting bracket (65).

3. The grouting model test system for karst tunnel water-rock interaction according to claim 2, characterized in that, The lifting frame (5) includes two sliding guide frames (51) slidably disposed on both sides of the extension support frame (2), and multiple support columns (52) fixed between the two sliding guide frames (51). The positions of the support columns (52) avoid the rotation trajectory of the mold frame (6). The rotating bracket (7) is rotatably disposed between the two sliding guide frames (51), and the support columns (52) are used to enhance the stability of the sliding guide frames (51).

4. The grouting model test system for karst tunnel water-rock interaction according to claim 3, characterized in that, The first drive assembly includes a ball screw I (53) that is rotatably mounted inside the test workbench (1). A screw nut (55) is sleeved on the outer wall of the ball screw I (53). The balls inside the screw nut (55) roll in the thread groove of the ball screw I (53). A fixed base I (54) is fixedly connected to the outer wall of the screw nut (55). The fixed base I (54) is fixedly mounted on the support column (52). A drive motor I (56) is fixed on one side of the test workbench (1). The output end of the drive motor I (56) is connected to the ball screw I (53) through a synchronous pulley and a synchronous belt to drive the lifting frame (5) to rise and fall.

5. The grouting model test system for karst tunnel water-rock interaction according to claim 3, characterized in that, The rotating bracket (7) includes a rotating spindle (71) that is rotatably mounted on one side of the sliding guide frame (51). A fixed base II (72) is fixedly sleeved on the outer wall of one end of the rotating spindle (71). The same supporting rib (73) is fixed between the two fixed bases II (72). The mold frame (6) is mounted on the supporting rib (73). The rotation of the rotating spindle (71) can drive the mold frame (6) to rotate synchronously.

6. The grouting model test system for karst tunnel water-rock interaction according to claim 5, characterized in that, The second drive assembly includes a drive motor II (75) fixed on one side of the sliding guide frame (51). A rotary transmission shaft (77) is rotatably mounted on the sliding guide frame (51) on one side of the drive motor II (75). The output end of the drive motor II (75) is connected to the rotary transmission shaft (77) through an elastic coupling (76). The outer wall of the rotary spindle (71) away from the fixed base II (72) and the end of the rotary transmission shaft (77) away from the elastic coupling (76) are both fixedly fitted with meshing transmission gears (78). The drive motor II (75) drives the rotary spindle (71) to rotate through gear transmission.

7. The grouting model test system for karst tunnel water-rock interaction according to claim 6, characterized in that, The outer wall of the supporting rib (73) is adjustable with an adjustable base (74), and the top of the adjustable base (74) is rotatably equipped with an electric push rod (79). The top of the electric push rod (79) is rotatably connected to the bottom of the outer frame (61). The extension and retraction of the electric push rod (79) can adjust the tilt angle of the mold frame (6) and, together with the rotating bracket (7), realize multi-angle simulation.

8. The grouting model test system for karst tunnel water-rock interaction according to claim 2, characterized in that, Two sets of partition plates (15) are fixed inside the outer frame (61). A buffer trough (16) is formed between the partition plates (15) and the outer frame (61). Water flows through the buffer trough (16) and then through the karst module (12). The karst module (12) is bilobed and located between the two sets of partition plates (15). A sealing rubber plate (14) is provided between adjacent karst modules (12). A drainage control valve (63) is connected to the outside of the outer frame (61). A discharge trough (17) is provided between each set of partition plates (15). Excess slurry is discharged through the discharge trough (17).

9. The grouting model test system for karst tunnel water-rock interaction according to claim 8, characterized in that, A displacement gap (18) is reserved between the karst module (12) and the outer frame (61). The karst module (12) can generate a small displacement along the displacement gap (18) under the action of water flow or slurry pressure to simulate the stress deformation of the surrounding rock.

10. A grouting model test method for karst tunnels under water-rock interaction, characterized in that, The grouting model test system for karst tunnel water-rock interaction as described in claim 7 includes the following steps: S1. Place the karst module (12) into the outer frame (61), adjust the top cover plate (62) to seal by using the transmission screw II (69), and inject water into the test workbench (1); S2. The mold frame (6) is immersed in water by the first drive component to test the sealing performance. If there are no air bubbles, the test is completed. S3. Adjust the second drive assembly and electric push rod (79) to the preset angle and start the camera to take pictures; S4. Start the grouting pump (9) to inject the grout into the grouting tank (13), and at the same time start the booster pump (8) to circulate the water flow and simulate the water-rock action. S5. After grouting is completed, let it stand until the grout solidifies, then disassemble the karst module (12) to remove the grout for testing and clean the equipment.

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