Adjustable scale multi-modal fracture channel mud penetration blockage test device and method

Abstract

The present invention relates to an adjustable-scale multi-modal fracture channel mud penetration and blockage test device and method. The adjustable-scale multi-modal fracture channel mud penetration and blockage test device includes an upper frame, a lower frame, a transparent glass, a fracture channel, a sealed fixed frame, an air compressor, a slurry storage barrel, an electric stirrer, a high-speed camera, an inlet pressure transmitter installation interface, an inlet pressure measuring hole, an outlet pressure transmitter installation interface, an outlet pressure measuring hole, a data acquisition instrument, a drainage collection barrel, a high-precision electronic scale, and a computer. The beneficial effect of the present invention is that it constructs a test platform with adjustable fracture channel geometric scale, variable channel mode, and full-process monitoring. It can systematically reveal the evolution law of penetration, blockage, and film formation of different types of mud in fracture structures. It is suitable for simulating the blockage mechanism and stability evaluation of mud in high-permeability fractured strata during slurry shield construction.

Description

Technical Field

[0001] The present invention relates to the technical field of shield construction excavation face stability research, and in particular to an adjustable scale multi-modal fissure channel mud penetration and blockage test device and method. Background Art

[0002] With the continuous expansion of tunnel construction, especially shield tunneling in high-pressure strata, the stability of excavation faces has attracted increasing attention. In slurry shield construction, one of the key factors in maintaining excavation face stability is the slurry's penetration and pressure-maintaining properties. Current research focuses on the slurry's penetration into soil and its impact on excavation face stability.

[0003] Traditional mud penetration test devices consist of permeable columns and model boxes. Their test subjects are primarily fine-grained or homogeneous soil layers. However, due to the varying properties of strata, especially the complex structures of fractured strata such as fault zones, which contain large rock blocks and fissures, the mud's penetration path and its blocking effect differ significantly from those in traditional soil layers. This makes it difficult for traditional mud penetration models and test devices to simulate and analyze mud penetration behavior in fractured strata. While permeable column devices can relatively simply simulate mud penetration behavior in a single direction, they cannot fully reflect the impact of fracture structure on mud penetration and its blocking effect. Existing model box devices can simulate the diffusion process of mud in three-dimensional strata, but are often limited by the scale and cost of the test and have certain limitations in observing stratum deformation and changes in excavation face stability.

[0004] As existing test equipment is unable to effectively simulate the complex physical phenomena of mud penetration in high permeability fractured formations such as fault fracture zones, such as the flow, distribution and blockage of mud between cracks, it has become an urgent problem to study a new mud penetration and blockage test device. Summary of the Invention

[0005] The purpose of the present invention is to overcome the shortcomings of the prior art and provide an adjustable scale multi-modal fracture channel mud penetration and blockage test device and method, which can study the influence of different particle sizes and seepage channel structures on mud penetration and blockage effects, and simulate and analyze the penetration and blockage behavior of mud in fracture channels in fragmented formations.

[0006] The purpose of the present invention is achieved through the following technical solutions:

[0007] An adjustable scale multi-modal fracture channel mud penetration and blockage test device, comprising:

[0008] The seepage main body system and the bracket, the seepage main body system includes an upper frame, a lower frame, a transparent glass, a crack channel, and a sealed fixed frame. The lower frame is arranged on the top of the bracket, the upper frame is arranged on the top of the lower frame, and the bottom surface of the upper frame is in contact with the top surface of the lower frame. A cavity is opened on the top surface of the lower frame, and the crack channel is arranged in the cavity and the size of the crack channel is adjustable. The top surface of the upper frame and the bottom surface of the lower frame are both provided with grooves, and the bottom surface of the groove is provided with a through hole connected to the cavity. The bottom surface of the groove around the through hole is provided with steps, and a transparent glass is provided in the through hole and the transparent glass is surrounded by steps. It is connected to the step, and a sealing gasket is provided at the joint of the perspective glass and the step. The sealing fixing frame is fixed to the bottom surface of the groove by hexagon socket screws and abuts against the four sides of the perspective glass. The two ends of the bottom surface of the lower frame are respectively provided with a slurry inlet hole and a slurry discharge hole near the edge of the groove. The slurry inlet hole and the slurry discharge hole are both connected to the cavity. The slurry inlet hole is provided with a slurry inlet hole joint, and the slurry discharge hole is provided with a slurry discharge hole joint. The top surface of the upper frame is provided with a circulation control hole that is connected to the cavity and opposite to the slurry inlet hole. The circulation control hole is provided with a circulation control joint, and the circulation control joint is provided with a circulation control valve.

[0009] The injection system includes an air compressor, a slurry storage barrel, and an electric stirrer. The air compressor is connected to the top of the slurry storage barrel through a pneumatic tube. The electric stirrer is arranged on the top of the slurry storage barrel. The bottom of the slurry storage barrel is connected to the slurry inlet joint through a liquid inlet pipe. The end of the liquid inlet pipe connected to the slurry storage barrel is provided with a first slurry inlet valve, and the end of the liquid inlet pipe connected to the slurry inlet joint is provided with a second slurry inlet valve.

[0010] Monitoring system, the monitoring system includes a high-speed camera, an inlet pressure transmitter installation interface, an inlet pressure measuring hole, an outlet pressure transmitter installation interface, an outlet pressure measuring hole, a data acquisition instrument, a drainage collection bucket, a high-precision electronic scale, and a computer. The high-speed camera is arranged above the upper frame, the inlet pressure measuring hole is arranged at one end of the bottom surface of the groove close to the slurry inlet hole, the outlet pressure measuring hole is arranged at one end of the bottom surface of the groove close to the slurry discharge hole, the inlet pressure measuring hole and the outlet pressure measuring hole are both connected to the cavity, the inlet pressure transmitter installation interface is arranged at the inlet pressure measuring hole, the outlet pressure transmitter installation interface is arranged at the outlet pressure measuring hole, the inlet pressure transmitter installation interface and the outlet pressure transmitter installation interface are both electrically connected to the data acquisition instrument, the drainage collection bucket is arranged on the high-precision electronic scale, the top of the drainage collection bucket is connected to the slurry discharge hole joint through a liquid outlet pipe, and a slurry discharge valve is provided at the end where the liquid outlet pipe is connected to the drainage collection bucket. The high-speed camera, the data acquisition instrument, and the high-precision electronic scale are all electrically connected to the computer.

[0011] Furthermore, a boss is provided on the top of the lower frame, the bottom surface of the upper frame is fitted with the top surface of the boss, a cavity is opened on the top surface of the boss, and the lower frame at both ends of the boss is fixed to the top of the bracket by stainless steel hexagonal screws.

[0012] Furthermore, the upper frame is connected to the boss by a stainless steel hexagonal screw, and a positioning pin is provided between the upper frame and the boss, with both ends of the positioning pin being inserted into the boss and the upper frame respectively.

[0013] Furthermore, the transparent glass is made of borosilicate glass.

[0014] Furthermore, two main boards are provided in the cavity, the two main boards are vertically parallel, the two main boards are in contact with each other through elastic support pads, the two main boards are respectively in contact with the bottom surface of the upper frame and the bottom surface of the cavity, and a crack channel is formed between the two main boards.

[0015] Furthermore, the two main boards are respectively in contact with the bottom surface of the upper frame and the bottom surface of the cavity through the auxiliary adjustment plate.

[0016] Furthermore, a left plate and a right plate are provided in the cavity, and the left plate and the right plate are horizontally parallel. The top surface of the left plate and the top surface of the right plate are both in contact with the bottom surface of the upper frame, and the bottom surface of the left plate and the bottom surface of the right plate are both in contact with the bottom surface of the cavity. The opposite sides of the left plate and the right plate are both in contact with the side wall of the cavity. The opposite sides of the left plate and the right plate are both provided with threaded holes, and the side walls of the boss are provided with sealing fixing screws corresponding to the threaded holes.

[0017] Furthermore, a crack network plate is provided in the cavity, and a plurality of crack channels are provided on the crack network plate.

[0018] Furthermore, a drainage ramp communicating with the slurry discharge hole is provided on the bottom surface of the cavity at the slurry discharge hole.

[0019] Furthermore, based on the above-mentioned adjustable-scale multi-modal fracture channel mud penetration and blockage test device, the present invention also provides an adjustable-scale multi-modal fracture channel mud penetration and blockage test method, comprising the following steps:

[0020] S1. Install the main seepage system, injection system, and monitoring system. Fix the main seepage system on the top of the bracket and place a fill light at the bottom of the bracket just below the perspective glass.

[0021] S2, open the first slurry inlet valve and the circulation control valve, close the second slurry inlet valve and the slurry discharge valve, inject water into the cavity through the circulation control valve, then open the slurry discharge valve to exhaust the entire circulation path, and after the exhaust is completed, close the slurry discharge valve and the circulation control valve in sequence;

[0022] S3. Run the air compressor and adjust the pressure valve on the air compressor to maintain the target pressure in the slurry storage tank. At the same time, use the electric agitator to fully stir the slurry in the slurry storage tank.

[0023] S4. Open the second slurry inlet valve, inject grout into the cavity and start the test. Use a high-speed camera to record the particle flow and blockage in the fracture channel, use a data acquisition instrument to collect the inlet and outlet pressures, and use a high-precision electronic scale to obtain the real-time change of the filtration loss.

[0024] S5. According to steps S1-S4, by arranging fracture channels of different scales, the seepage blockage conditions of different mud particle compositions and forms in different fracture channels are recorded.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1. The present invention can simulate the effects of different types of strata on mud penetration through the configuration of a seepage main system, an injection system, and a monitoring system. Compared with traditional seepage column and model box devices, it can more realistically reflect the actual penetration behavior of mud in fractured strata, thereby providing effective experimental data support for mud selection and stratum stability research in shield construction. It can be applied to studying the characteristics of mud penetration under different stratum conditions and its influence on the stability of the excavation face.

[0027] 2. The present invention can select different fracture channel layout schemes according to the test requirements, and can accurately control the mud penetration process in the fracture channel by adjusting the scale of the fracture channel, and then study the influence of different particle sizes and fracture channels on mud penetration and blockage effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0029] Figure 2 This is an exploded schematic diagram of the overall structure of the infiltration main body system of the present invention;

[0030] Figure 3 Schematic diagram of the internal structure of the infiltration main body system of the present invention;

[0031] Figure 4 Schematic diagram of the layout of the seepage channel in the present invention Figure 1 ;

[0032] Figure 5 Schematic diagram of the layout of the seepage channel in the present invention Figure 2 ;

[0033] Figure 6 Schematic diagram of the layout of the seepage channel in the present invention Figure 3 ;

[0034] Figure 7 Schematic diagram of the layout of the seepage channel in the present invention Figure 4 .

[0035] In the figure: 1. Upper frame; 2. Lower frame; 2-1. Slurry inlet joint; 2-2. Slurry outlet joint; 2-3. Inlet pressure transmitter installation interface; 2-4. Outlet pressure transmitter installation interface; 2-5. Inlet pressure measuring hole; 2-6. Outlet pressure measuring hole; 2-7. Circulation control joint; 2-8. Drainage ramp; 2-9. Layout cavity; 3. Transparent glass; 4. Sealing fixing frame; 5. Positioning pin; 6. Sealing fixing screw; 6-1. Thread; 7. Hexagon socket screw; 8. Stainless steel hexagon socket screw; 10 -1. Main board; 10-2. Elastic support pad; 10-3. Auxiliary adjustment plate; 10-4. Right plate; 10-5. Left plate; 10-6. Fracture network plate; 11. Bracket; 12. Fill light; 13. Air compressor; 14. High-speed camera; 15. Slurry storage barrel; 16. Electric agitator; 17. Data acquisition instrument; 18. Drainage collection barrel; 19. High-precision electronic scale; 20. Computer; 21-1. First slurry inlet valve; 21-2. Circulation control valve; 21-3. Second slurry inlet valve; 21-4. Slurry discharge valve. DETAILED DESCRIPTION

[0036] The present invention will be further described below in conjunction with the accompanying drawings, but the protection scope of the present invention is not limited to the following description.

[0037] A scale-adjustable multi-modal fracture channel mud penetration blockage test device comprises a support 11, a seepage main body system, an injection system, and a monitoring system.

[0038] like Figure 1-Figure 3As shown, the seepage main body system includes an upper frame 1, a lower frame 2, a transparent glass 3, a crack channel, and a sealed fixed frame 4. The lower frame 2 is fixed to the top of the bracket 11, and the upper frame 1 is fixed to the top of the lower frame 2, and the bottom surface of the upper frame 1 is in contact with the top surface of the lower frame 2; the top surface of the lower frame 2 is provided with a cavity 2-9, and the cavity 2-9 is used to arrange the crack channel, and the size of the crack channel in the cavity 2-9 is adjustable; the top surface of the upper frame 1 and the bottom surface of the lower frame 2 are both provided with grooves, and the bottom surface of the groove is provided with a through hole connected to the cavity 2-9, and the bottom surface of the groove around the through hole is provided with steps, and the size of the through hole is adapted to the size of the transparent glass 3, and the transparent glass 3 can be stuck in the through hole and overlapped on the steps; a sealing gasket is provided at the overlap of the transparent glass 3 and the step. The sealing and fixing frame 4 is fixed to the bottom surface of the groove by the hexagon socket screws 7 and abuts against the four sides of the transparent glass 3, thereby fixing the transparent glass 3 and ensuring the sealing; the two ends of the bottom surface of the lower frame 2 are respectively provided with a slurry inlet hole and a slurry discharge hole near the edge of the groove. The slurry inlet hole and the slurry discharge hole are both connected with the cavity 2-9. A slurry inlet hole joint 2-1 is installed at the slurry inlet hole, and a slurry discharge hole joint 2-2 is installed at the slurry discharge hole. A circulation control hole that is connected with the cavity 2-9 and opposite to the slurry inlet hole is opened on the top surface of the upper frame 1. A circulation control joint 2-7 is installed at the circulation control hole, and a circulation control valve 21-2 is installed on the circulation control joint 2-7.

[0039] The injection system injects slurry into cavity 2-9 through inlet connector 2-1, allowing the slurry to enter the fracture channel. Mud penetration and blockage within the fracture channel can be observed through transparent glass 3. Based on the research range of mud particle size, the inlet and outlet holes are both 16 mm in diameter to facilitate smooth passage of mud particles. Considering the interfacial wear caused by long-term friction between mud particles and transparent glass 3 during the experiment, transparent glass 3 is made of borosilicate glass. This provides a certain degree of light transmittance, facilitating observation while reducing interfacial wear.

[0040] like Figure 2 、 Figure 3 As shown, in order to facilitate the installation and fixation of the upper frame 1 and the lower frame 2, a boss is provided on the top of the lower frame 2, the boss and the lower frame 2 are integrally formed, the boss height is 15 mm, and a cavity 2-9 is provided on the top surface of the boss. The lower frame 2 at both ends of the boss is fixed to the top of the bracket 11 by stainless steel hexagonal screws 8. A locating pin 5 is provided between the upper frame 1 and the boss, and locating holes corresponding to the locating pin 5 are provided on the upper frame 1 and the boss. When installing the upper frame 1, the two ends of the locating pin 5 are respectively inserted into the boss and the upper frame 1 through the locating holes, and the bottom surface of the upper frame 1 is fit with the top surface of the boss, thereby positioning the upper frame 1, and then the upper frame 1 is fixed to the boss by the stainless steel hexagonal screws 8.

[0041] like Figure 1As shown, the injection system includes an air compressor 13, a slurry storage barrel 15, and an electric agitator 16. The air compressor 13 is connected to the top of the slurry storage barrel 15 through a pneumatic tube. The pressure in the slurry storage barrel 15 can be adjusted by a pressure valve on the air compressor 13. The bottom of the slurry storage barrel 15 is connected to the slurry inlet joint 2-1 through a liquid inlet pipe. The end of the liquid inlet pipe connected to the slurry storage barrel 15 is installed with a first slurry inlet valve 21-1, and the end of the liquid inlet pipe connected to the slurry inlet joint 2-1 is installed with a second slurry inlet valve 21-3. When the first and second slurry inlet valves 21-1 and 21-3 are opened, the slurry in the slurry storage barrel 15 is injected into the cavity 2-9 through the liquid inlet pipe by a multi-channel material conveying pump. The electric agitator 16 is installed on the top of the slurry storage barrel 15 and is used to stir the slurry in the slurry storage barrel 15 to control the sedimentation of particles in the slurry. To avoid particle crushing, the speed of the electric agitator 16 can be appropriately selected.

[0042] like Figure 1As shown, the monitoring system includes a high-speed camera, an inlet pressure transmitter installation interface 2-3, an inlet pressure measuring hole 2-5, an outlet pressure transmitter installation interface 2-4, an outlet pressure measuring hole 2-6, a data acquisition instrument 17, a drainage collection bucket 18, a high-precision electronic scale 19, and a computer 20. The high-speed camera, the data acquisition instrument 17, and the high-precision electronic scale are all electrically connected to the computer 20. A high-speed camera is installed above the upper frame 1, and records the blockage of mud in the fracture channel by shooting, and uploads the shooting results to the computer 20, which is convenient for analyzing the penetration behavior, blockage mode, etc. of different particle sizes and forms in the fracture; an inlet pressure measuring hole 2-5 is provided at one end of the bottom surface of the groove close to the slurry inlet hole, and an outlet pressure measuring hole 2-6 is provided at one end of the bottom surface of the groove close to the slurry discharge hole. The distance between the inlet pressure measuring hole 2-5 and the slurry inlet hole, and the distance between the outlet pressure measuring hole 2-6 and the slurry discharge hole are both 5mm. The inlet pressure measuring hole 2-5 and the outlet pressure measuring hole 2-6 are both connected to the cavity 2-9, the inlet pressure transmitter installation interface 2-3 is installed at the inlet pressure measuring hole 2-5, and the outlet pressure transmitter installation interface 2-4 is installed at the outlet pressure measuring hole 2-6. The inlet pressure transmitter installation interface 2-3 and the outlet pressure transmitter installation interface 2-4 are both electrically connected to the data acquisition instrument 17, and the mud is injected. The cavity 2-9 will be filtered out from the slurry discharge hole after penetrating the fracture channel. The pressure at the slurry inlet and discharge holes can be monitored and collected through the inlet pressure measuring hole 2-5, the outlet pressure measuring hole 2-6, the inlet pressure transmitter installation interface 2-3, the outlet pressure transmitter installation interface 2-4 and the data acquisition instrument 17. The collected pressure data is uploaded to the computer 20 for recording and preservation, so as to judge whether the pressure meets the test conditions based on the pressure monitoring results, and then analyze the mud blockage in the fracture channel; the drainage collection barrel 18 is placed on a high-precision electronic scale 19, and the top of the drainage collection barrel 18 is connected to the slurry discharge hole joint 2-2 through a liquid outlet pipe. A slurry discharge valve 21-4 is installed at one end of the liquid outlet pipe connected to the drainage collection barrel 18. The filtered mud is discharged through the slurry discharge hole and then discharged into the drainage collection barrel 18 through the liquid outlet pipe. Then, the real-time change of the mud filtration loss can be measured by the high-precision electronic scale 19, and the measurement results are uploaded to the computer 20. In order to facilitate the smooth filtration of mud, such as Figure 3 As shown, a drainage ramp 2-8 communicating with the slurry discharge hole is provided on the bottom surface of the cavity 2-9 at the slurry discharge hole.

[0043] To improve test efficiency and simulate the effects of corrosive seawater on mud film formation, multiple sets of slurry storage barrels 15 and additional chemical solution storage tanks can be installed. The chemical solution storage tanks are connected to the multiple sets of slurry storage barrels 15 via pipelines. Solenoid valves are installed in the connecting pipelines between the chemical storage tanks and the slurry storage barrels 15, and pH and conductivity sensors are installed in cavities 2-9. Multiple sets of slurry storage barrels can store muds with different mix ratios, eliminating the need for frequent mud changes and tank cleaning during testing. This achieves dynamic multi-slurry injection and allows for the study of multi-layer and multi-stage effects from thin to thick mud. Chemical solutions from the chemical solution storage tanks are passed into the slurry storage barrels, then stirred with an electric stirrer to mix the chemical solution and mud. The mixing ratio of the chemical solution and mud can be controlled by a solenoid valve. Combined with pH and conductivity sensors, the pH and conductivity of the mud in the fracture channel are detected and controlled. This allows monitoring the blockage of mud particles in the seepage channel and analyzing the effects of the seawater environment on the mud film.

[0044] In order to facilitate the control of the particle gradation of the mud, a multi-channel material conveying pump and a concentration / density sensor are installed in the slurry storage barrel 15, the concentration / density sensor is connected to the data acquisition instrument 17, the electric stirrer 16 is connected to the computer 20, and the multi-channel material conveying pump is connected to the slurry inlet hole joint 2-1 through the liquid inlet pipe at the bottom of the slurry storage barrel 15; the concentration / density sensor is used to detect the concentration / density of the mud in the slurry storage barrel 15, and then the concentration / density data is collected and transmitted to the computer through the data acquisition instrument 17. The computer 20 then controls the electric stirrer 16 to adjust the particle gradation of the mud according to the concentration / density detection results. After adjustment, the mud is injected into the cavity 2-9 through the multi-channel material conveying pump.

[0045] To improve the applicability and flexibility of the experimental device, the present invention adopts three layout schemes for scale-variable fracture channels: upper and lower plates, left and right plates, and a single fracture network plate. These layouts can be selected based on experimental requirements. It should be noted that both the upper and lower plate and left and right plate layouts are used to simulate a single fracture channel. The upper and lower plate layout is suitable for studying the seepage and blockage behavior of mud from the perspective of fracture width, while the left and right plate layout is used to conduct research from the perspective of fracture aperture. The single fracture network plate scheme is used to construct a multi-fracture channel structure to simulate complex seepage paths that are closer to the actual fracture network in the formation, thereby enabling systematic research on the seepage and blockage behavior of multiple fractures.

[0046] Upper and lower plate schemes such as Figure 4As shown, two main boards 10-1 are used, and the two main boards 10-1 are placed vertically and in parallel in the cavity 2-9. The two main boards 10-1 are abutted against each other through elastic support pads 10-2 on all sides, and the two main boards 10-1 are respectively abutted against the bottom surface of the upper frame 1 and the bottom surface of the cavity 2-9, so that a crack channel is formed between the two main boards 10-1; in order to better adapt to test conditions of different crack sizes, an auxiliary adjustment plate 10-3 is additionally provided, as shown in FIG. Figure 5 As shown, auxiliary adjustment plates 10-3 are placed on the top surface of the upper main board 10-1 and the bottom surface of the lower main board 10-1, so that the two main boards 10-1 are respectively abutted against the bottom surface of the upper frame 1 and the bottom surface of the cavity 2-9 through the auxiliary adjustment plates 10-3. In the cavity 2-9 with fixed and limited space, by selecting auxiliary adjustment plates 10-3 of different thicknesses and cooperating with elastic support pads 10-2, the scale of the crack channel can be freely adjusted within the range of 0-15mm. In addition, the elastic support pads 10-2 need to select appropriate sizes according to the scale of the cracks at the installation position to avoid affecting the crack channel due to excessive extrusion; in addition, according to the roughness JRC of the actual rock surface, 3D printing technology can be used to print main boards 10-1 with different roughness to realize different types of crack channels, such as planar, wedge-shaped and irregular types, among which the planar type is as Figure 4 As shown, the two main plates 10-1 have opposite sides that are plane, so that the crack channels have the same length dimensions; the wedge-shaped Figure 5 As shown, the opposite sides of the two main plates 10-1 are inclined, so that the scale of the fracture channel in the length direction gradually becomes smaller or larger; the irregular type, that is, the opposite sides of the two main plates 10-1 are irregular, is more consistent with the description of the actual fracture contour surface between rocks, and the profile contour line can be determined in combination with JRC.

[0047] Left and right board solutions Figure 6As shown, a left plate 10-5 and a right plate 10-4 are used, and the left plate 10-5 and the right plate 10-4 are placed in parallel in the cavity 2-9, so that the top surface of the left plate 10-5 and the top surface of the right plate 10-4 are both in contact with the bottom surface of the upper frame 1, the bottom surface of the left plate 10-5 and the bottom surface of the right plate 10-4 are both in contact with the bottom surface of the cavity 2-9, and the opposite sides of the left plate 10-5 and the right plate 10-4 are both in contact with the side wall of the cavity 2-9, and a crack channel is formed between the left plate 10-5 and the right plate 10-4. By using left plates 10-5 and right plates 10-4 of different widths, a crack channel can be formed. To adjust the size of the fissure channel, threaded holes 6-1 are provided on the opposite sides of the left and right plates 10-5, 10-4. The sidewalls of the bosses are provided with sealing screws 6 that connect to the threaded holes 6-1. After the left and right plates 10-5, 10-4 are placed, the sealing screws 6 are screwed into the left and right plates 10-5, 10-4 through the threaded holes 6-1 to secure them. This prevents the pressure difference caused by the movement of the mud fluid from causing the left and right plates 10-5, 10-4 to move, ensuring that the size of the fissure channel is stable and controllable. Similarly, depending on the roughness of the rock, 3D printing technology can be used to produce left and right plates 10-5, 10-4 that meet the test requirements.

[0048] Crack network single board solution such as Figure 7 As shown, a single fracture network plate 10-6 is directly placed in the cavity 2-9, and multiple fracture channels are provided on the fracture network plate 10-6, thereby reflecting the mud penetration and blockage problem under the actual multi-fracture fractured rock formation. The distribution of the fracture channels can be reconstructed into a model using 3D printing technology according to the working conditions to be studied.

[0049] When adopting the upper and lower plate scheme, to more conveniently adjust the size of the fracture channel, a micro-servo telescopic motor can be installed on the end of the elastic support pad 10-2 that abuts the main board 10-1, and a displacement sensor can be installed at the output end of the micro-servo telescopic motor, so that the telescopic end of the micro-servo telescopic motor abuts the main board 10-1 through the displacement sensor. The micro-servo telescopic motor and displacement sensor are connected to a computer. When the data acquisition device 17 detects that the inlet and outlet pressure difference exceeds a threshold, the PLC control system automatically adjusts the micro-servo telescopic motor's expansion and contraction, thereby changing the fracture width. This simulates the dynamic evolution of fractures under changing formation stress. Ultimately, through a closed-loop control system of "monitoring-analysis-adjustment", an adaptive mechanism is introduced into mud penetration testing to solve the problem of simulating the dynamic response of fractures in real formations to changing water pressure.

[0050] When conducting a test using the above-mentioned adjustable scale multi-modal fracture channel mud penetration blockage test device, the following steps are specifically included:

[0051] S1. Install the seepage main system, injection system and monitoring system. Fix the seepage main system on the top of the bracket 11 and place the fill light 12 at the bottom of the bracket 11 just below the perspective glass 3.

[0052] When installing the seepage main system, place the perspective glass 3 in the through hole of the upper frame 1 in order, then fix the sealing fixing frame 4 with the inner hexagon screw 7, fix the perspective glass 3 to the upper frame 1, and install the circulation control joint 2-7. Similarly, fix the perspective glass 3 on the lower frame 2 in order, and install the slurry inlet joint 2-1, slurry discharge joint 2-2, inlet pressure transmitter installation interface 2-3, and outlet pressure transmitter installation interface 2-4. Then, fix the lower frame 2 to the bracket 11 with the stainless steel outer hexagon screw 8, and select the fracture channel layout scheme according to the test requirements and lay out the fracture channel in the cavity 2-9. Then, fix the upper frame 1 to the lower frame 2 with the stainless steel outer hexagon screw 8, and place the fill light 12 on the bracket 11 to facilitate observation through the perspective glass 3 and high-speed camera shooting.

[0053] When installing the injection system, after connecting the slurry storage barrel 15 to the slurry inlet hole joint 2-1 through the liquid inlet pipe, the first slurry inlet valve 21-1 and the second slurry inlet valve 21-3 are adjusted to fill the liquid inlet pipe with slurry to prevent air from being subsequently injected into the cavity 2-9.

[0054] S2. Before the experiment, cavity 2-9 needs to be saturated. First, open the first slurry inlet valve 21-1 and the circulation control valve 21-2, close the second slurry inlet valve 21-3 and the slurry discharge valve 21-4, inject water into cavity 2-9 through the circulation control valve 21-2, and then open the slurry discharge valve 21-4 to exhaust the entire circulation path. After the exhaust is completed, close the slurry discharge valve 21-4 and the circulation control valve 21-2 in sequence.

[0055] S3, running the air compressor 13 and adjusting the pressure valve on the air compressor 13 to maintain the target pressure value in the slurry storage barrel 15, while fully stirring the mud in the slurry storage barrel 15 through the electric stirrer 16.

[0056] S4. Open the second slurry inlet valve 21-3, inject grout into cavity 2-9, and begin the test. During the test, a high-speed camera records the particle flow and blockage in the fracture channel. A data acquisition device 17 collects inlet and outlet pressures, and a high-precision electronic scale 19 measures the real-time change in fluid loss. If the measurement result of the high-precision electronic scale 19 shows a small change, the test is terminated. Otherwise, the grouting time is set to 30 minutes, and the test is then terminated.

[0057] S5. According to the above steps S1-S4, by arranging fracture channels of different sizes, the seepage blockage conditions of different mud particle compositions and forms in different fracture channels are recorded.

[0058] During the test, a heating plate and insulation layer can be added to the inner wall of cavity 2-9, and a temperature sensor can be installed inside cavity 2-9. The heating plate and insulation layer heat and insulate cavity 2-9, and the temperature sensor is used to detect the temperature inside cavity 2-9, simulating a temperature gradient of 5-80°C within cavity 2-9. A pressure pulse transmitter can also be installed on the pneumatic pipeline to generate periodic pulsating pressures of 0.02-1 MPa, simulating the pressure fluctuations in the incision during slurry shield construction. Ultimately, by incorporating temperature and pulsating pressure fields into the slurry penetration test, the limitation of traditional devices that can only simulate static water pressure can be overcome, allowing for the complex working conditions of other high water pressure or high ground temperature environments to be met.

[0059] The monitoring data obtained during the test is transmitted to the computer 20 for data analysis. An LSTM neural network model based on deep learning can be implanted in the data analysis software of the computer 20. By inputting historical test data (pressure, filtration loss, particle migration images, etc.), the critical state of mud blockage (such as film formation time and blockage area) can be predicted in real time. Ultimately, by deeply integrating artificial intelligence technology with the test device, the device is given a "predictive" function, which improves the test efficiency and data utilization rate compared to the "post-analysis" mode of traditional monitoring devices.

[0060] Based on the above-mentioned adjustable-scale multi-modal fracture channel mud penetration and blockage test device and the corresponding test method, the present invention can more realistically reflect the penetration and blockage effect of mud in fractured formations (such as rock cracks in fault fracture zones) by simulating the mud penetration and blockage behavior of formation fracture channels, and can study the influence of different particle sizes and penetration channel structures on mud penetration and blockage effects, thereby providing effective experimental data support for mud selection and formation stability research in shield construction, and can be applied to study the characteristics of mud penetration under different formation conditions and its influence on excavation face stability.

[0061] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. An adjustable scale multi-modal fracture channel mud penetration and blockage test device, characterized in that: include: A seepage main body system and a bracket (11), the seepage main body system includes an upper frame (1), a lower frame (2), a transparent glass (3), a crack channel, and a sealed fixed frame (4), the lower frame (2) is arranged on the top of the bracket (11), the upper frame (1) is arranged on the top of the lower frame (2), and the bottom surface of the upper frame (1) is in contact with the top surface of the lower frame (2), the top surface of the lower frame (2) is provided with a cavity (2-9), the crack channel is arranged in the cavity (2-9), and the size of the crack channel is adjustable, the top surface of the upper frame (1) and the bottom surface of the lower frame (2) are both provided with grooves, the bottom surface of the groove is provided with a through hole connected to the cavity (2-9), the bottom surface of the groove around the through hole is provided with steps, the through hole is provided with a transparent glass (3), and the transparent glass ( 3) The periphery of the frame is overlapped on the step, and a sealing gasket is provided at the overlap of the perspective glass (3) and the step. The sealing fixing frame (4) is fixed to the bottom surface of the groove by means of hexagon socket screws (7) and is in contact with the periphery of the perspective glass (3). Both ends of the bottom surface of the lower frame (2) are provided with a slurry inlet hole and a slurry discharge hole near the edge of the groove. The slurry inlet hole and the slurry discharge hole are both connected to the cavity (2-9). The slurry inlet hole is provided with a slurry inlet hole joint (2-1), and the slurry discharge hole is provided with a slurry discharge hole joint (2-2). The top surface of the upper frame (1) is provided with a circulation control hole which is connected to the cavity (2-9) and is opposite to the slurry inlet hole. The circulation control hole is provided with a circulation control joint (2-7), and the circulation control joint (2-7) is provided with a circulation control valve (21-2); An injection system, the injection system includes an air compressor (13), a slurry storage barrel (15), and an electric stirrer (16). The air compressor (13) is connected to the top of the slurry storage barrel (15) through a pneumatic tube. The electric stirrer (16) is arranged on the top of the slurry storage barrel (15). The bottom of the slurry storage barrel (15) is connected to the slurry inlet joint (2-1) through a liquid inlet pipe. The end of the liquid inlet pipe connected to the slurry storage barrel (15) is provided with a first slurry inlet valve (21-1). The end of the liquid inlet pipe connected to the slurry storage barrel (15) is provided with a second slurry inlet valve (21-3). The monitoring system includes a high-speed camera, an inlet pressure transmitter installation interface (2-3), an inlet pressure measuring hole (2-5), an outlet pressure transmitter installation interface (2-4), an outlet pressure measuring hole (2-6), a data acquisition instrument (17), a drainage collection bucket (18), a high-precision electronic scale (19), and a computer (20). The high-speed camera is arranged above the upper frame (1), the inlet pressure measuring hole (2-5) is arranged at one end of the bottom surface of the groove close to the slurry inlet hole, the outlet pressure measuring hole (2-6) is arranged at one end of the bottom surface of the groove close to the slurry discharge hole, the inlet pressure measuring hole (2-5) and the outlet pressure measuring hole (2-6) are both connected to the cavity (2-9), and the inlet pressure transmitter is connected to the cavity (2-9). The pressure transmitter installation interface (2-3) is provided at the inlet pressure measuring hole (2-5), the outlet pressure transmitter installation interface (2-4) is provided at the outlet pressure measuring hole (2-6), the inlet pressure transmitter installation interface (2-3) and the outlet pressure transmitter installation interface (2-4) are electrically connected to the data acquisition instrument (17), the drainage collection bucket (18) is provided on the high-precision electronic scale (19), the top of the drainage collection bucket (18) is connected to the slurry discharge hole joint (2-2) through the liquid discharge pipe, and a slurry discharge valve (21-4) is provided at one end of the liquid discharge pipe connected to the drainage collection bucket (18), and the high-speed camera, the data acquisition instrument (17), the high-precision electronic scale (19), are electrically connected to the computer (20).

2. The adjustable scale multi-modal fracture channel mud penetration and blockage test device according to claim 1 is characterized by: A boss is provided on the top of the lower frame (2), the bottom surface of the upper frame (1) is fitted with the top surface of the boss, a cavity (2-9) is provided on the top surface of the boss, and the lower frame (2) at both ends of the boss is fixed to the top of the bracket (11) by stainless steel hexagonal screws (8).

3. The adjustable scale multi-modal fracture channel mud penetration and blockage test device according to claim 2, characterized in that: The upper frame (1) is connected to the boss via a stainless steel hexagonal screw (8). A positioning pin (5) is provided between the upper frame (1) and the boss, and both ends of the positioning pin (5) are respectively inserted into the boss and the upper frame (1).

4. The adjustable scale multi-modal fracture channel mud penetration and blockage test device according to claim 1, characterized in that: The perspective glass (3) is made of borosilicate glass.

5. The adjustable scale multi-modal fracture channel mud penetration and blockage test device according to claim 1, characterized in that: Two main boards (10-1) are provided in the cavity (2-9). The two main boards (10-1) are vertically parallel. The two main boards (10-1) are in contact with each other via elastic support pads (10-2) on all sides. The two main boards (10-1) are in contact with the bottom surface of the upper frame (1) and the bottom surface of the cavity (2-9) respectively, and a crack channel is formed between the two main boards (10-1).

6. The adjustable scale multi-modal fracture channel mud penetration and blockage test device according to claim 5, characterized in that: The two main boards (10-1) are respectively in contact with the bottom surface of the upper frame (1) and the bottom surface of the cavity (2-9) through the auxiliary adjustment plate (10-3).

7. The adjustable scale multi-modal fracture channel mud penetration and blockage test device according to claim 1, characterized in that: A left plate (10-5) and a right plate (10-4) are provided in the cavity (2-9). The left plate (10-5) and the right plate (10-4) are arranged in parallel in the horizontal direction. The top surfaces of the left plate (10-5) and the right plate (10-4) are both in contact with the bottom surface of the upper frame (1). The bottom surfaces of the left plate (10-5) and the right plate (10-4) are both in contact with the bottom surface of the cavity (2-9). The opposite sides of the left plate (10-5) and the right plate (10-4) are both in contact with the side wall of the cavity (2-9). A crack channel is formed between the left plate (10-5) and the right plate (10-4). The opposite sides of the left plate (10-5) and the right plate (10-4) are both provided with threaded holes (6-1). The side walls of the bosses are provided with sealing fixing screws (6) correspondingly connected to the threaded holes (6-1).

8. The adjustable scale multi-modal fracture channel mud penetration and blockage test device according to claim 1, characterized in that: A crack network plate (10-6) is provided in the cavity (2-9), and a plurality of crack channels are provided on the crack network plate (10-6).

9. The adjustable scale multi-modal fracture channel mud penetration and blockage test device according to claim 1, characterized in that: The bottom surface of the cavity (2-9) is provided with a drainage ramp (2-8) at the slurry discharge hole and is communicated with the slurry discharge hole.

10. A test method for the adjustable scale multi-modal fracture channel mud penetration and blockage test device according to claim 1, characterized in that: The following steps are involved: S1, installing the seepage main system, injection system and monitoring system, fixing the seepage main system on the top of the bracket (11) and placing a fill light (12) at the bottom of the bracket (11) just below the perspective glass (3); S2, opening the first slurry inlet valve (21-1) and the circulation control valve (21-2), closing the second slurry inlet valve (21-3) and the slurry discharge valve (21-4), injecting water into the cavity (2-9) through the circulation control valve (21-2), then opening the slurry discharge valve (21-4) to exhaust the entire circulation path, and after the exhaust is completed, closing the slurry discharge valve (21-4) and the circulation control valve (21-2) in sequence; S3, operating the air compressor (13) and adjusting the pressure valve on the air compressor (13) to maintain the target pressure value in the slurry storage barrel (15), while fully stirring the slurry in the slurry storage barrel (15) through the electric stirrer (16); S4, opening the second slurry inlet valve (21-3), injecting grout into the cavity (2-9) and starting the test, recording the particle flow and blockage in the fracture channel by a high-speed camera, collecting the inlet pressure and outlet pressure by a data acquisition instrument (17), and obtaining the real-time change of the filtration loss by a high-precision electronic scale (19); S5. According to steps S1-S4, by arranging fracture channels of different scales, the seepage blockage conditions of different mud particle compositions and forms in different fracture channels are recorded.

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