THMC-b coupling soft rock shear rheological test system and test method

Abstract

The application belongs to the technical field of rock mechanics test, and particularly relates to a THMC-B coupling soft rock shear rheological test system and a test method. The test system is composed of a shear box, a compression-shear system, a seepage system, a chemical erosion system, a temperature circulation system, a vibration loading system, a data monitoring and intelligent control system, the compression-shear system and the temperature circulation system arranged outside the shear box are used to simulate stress field and temperature field respectively, the seepage system and the chemical erosion system connected with the water / gas channel of the shear box are used to simulate seepage field and chemical field respectively, the vibration loading system is used to simulate blasting disturbance by impacting the shear box, and the data monitoring and intelligent control system is used to control test parameters. The test system can carry out THMC-B coupling shear rheological test without disassembling the shear box, can dynamically simulate the multi-field coupling effect of the stress state of soft rock, chemical field, temperature field, seepage field and blasting disturbance, and the test method is simple in operation, high in automation degree and test efficiency.

Description

Technical Field

[0001] This invention belongs to the field of rock mechanics testing technology, specifically relating to a THMC-B coupled soft rock shear rheology testing system and method. Background Technology

[0002] The rheological properties of rocks are a widely recognized issue in various geotechnical engineering projects, especially for high slopes in open-pit mines containing numerous weak interlayers. Shear rheological deformation often occurs along these weak rock layers (soft rock). Under the long-term influence of hydrological, chemical, thermal, mechanical, and blasting disturbances, the rheological parameters of these rocks continuously deteriorate, ultimately leading to slope failure. Studying the shear rheological characteristics of these weak interlayers under THMC-B multi-field coupling is crucial for investigating the stability and sliding mechanism of high slopes in open-pit mines. Laboratory testing is the most effective and convenient method for studying these shear rheological properties. Therefore, there is an urgent need to develop a THMC-B coupled rock shear rheological testing system that can simulate actual engineering geological conditions and various environmental influencing factors.

[0003] Currently, the development of multi-field coupled shear rheological testing systems faces several key challenges: First, the shear box's leak prevention during testing. Shear rheological tests are lengthy, and high-pressure seepage can easily lead to poor sealing and leakage, affecting test results. If chemical field coupling experiments are conducted simultaneously, leakage from the shear box can also corrode the equipment. Second, the concentrations of various ions in the chemical solution need to be adjusted promptly according to the experimental plan. Current chemical field testing devices mostly determine the solution concentration before the test, which cannot meet the requirements of shear rheological tests under precise changes in ion concentrations. Third, the high and low temperature cycling efficiency is low during testing, especially after reaching zero degrees Celsius and lower, where cooling efficiency is slow and rapid temperature cycling cannot be effectively achieved. Fourth, existing impact devices mostly employ pendulums or drop hammers. These devices are primarily used to simulate the impact resistance of materials and cannot simulate the parameters of blasting disturbances. However, the impact of blasting disturbances on mine slope rock masses is characterized by small damage from a single disturbance, numerous disturbances, and long-term cumulative damage. Furthermore, different blasting disturbance parameter values ​​can significantly affect the rheological properties of rock samples. Existing impact devices cannot adequately simulate the influence of blasting disturbances and their parameter values ​​on the rheological properties of rock samples. Fifth, current equipment cannot monitor various factors in real time during the experiment. Considering the complexity of multi-field coupling, intelligent monitoring of the experimental system is essential for revealing the shear rheological properties of rock samples under multi-field coupling conditions.

[0004] Chinese invention patent CN 110779811 B discloses a test system for simulating soft rock shear rheology by coupling rainfall seepage and blasting vibration, but it cannot be directly applied to THMC-B multi-field coupling conditions. In order to reveal the shear rheological characteristics of soft rock under THMC-B multi-field coupling conditions, it is necessary to further develop a test system and test method that can solve the above problems. Summary of the Invention

[0005] To address the problems existing in the prior art, the purpose of this invention is to provide a THMC-B coupled soft rock shear rheology testing system and method, which can equivalently and dynamically simulate the multi-field coupling effects of geostress, chemical field, temperature field, seepage field, and blasting disturbance in soft rock. This testing system and method are simple to operate, highly automated, and efficient, providing important fundamental research equipment for studying the shear rheology characteristics and failure evolution of soft rock. The specific technical solution adopted is as follows:

[0006] A THMC-B coupled soft rock shear rheology testing system includes at least a compression-shear system and a shear box located within the compression-shear system. The shear box consists of an upper shear box composed of a top plate, an upper shear body, a normal loading head, a normal loading pad, a water / air channel, and a specimen joint, and a lower shear box located at the bottom of the upper shear box. The top plate of the upper shear box has a circular through hole through which the normal loading head passes and abuts against the normal loading pad. A water / air channel is provided in the normal loading head. The normal loading pad has three equally spaced water / air channels, each with a specimen joint installed. The water / air channel of the normal loading head extends downward to connect with the three water / air channels in the normal loading pad. The system is characterized by further including a compression-shear system, a seepage system, a chemical erosion system, a temperature cycling system, a vibration loading system, and a data monitoring and intelligent control system.

[0007] The compression shearing system includes a fixed base, a normal phase loading electric cylinder located directly above the shear box, a horizontal loading electric cylinder located on the right side of the lower shear box, and a reaction column located on the left side of the upper shear box. The fixed base is a hollow frame, and the shear box is located inside the fixed base. The fixed base has a through hole on the top, right, and left sides, and the three through holes are respectively used to fix the bases of the normal phase loading electric cylinder, the horizontal loading electric cylinder, and the reaction column.

[0008] The seepage system includes a water pressure loading device and a pneumatic pressure loading device. The water pressure loading device includes a neutral distilled water tank, a water pump, a high-pressure water pipe, a fine-tuning rod on the high-pressure water pipe, an accumulator, a water pressure regulating valve, a water stop valve, a pressure gauge, and a flow meter. The pneumatic pressure loading device includes an air compressor, a pneumatic pressure regulating valve, and a pressure gauge. The high-pressure water pipe outlet of the water pressure loading device and the air pipe outlet of the pneumatic pressure loading device are both connected to the water / air channel of the normal loading head of the shear box.

[0009] The chemical erosion system includes an automatic chemical solution mixing device, a chemical water pump located below the automatic chemical solution mixing device, and a chemical water pressure controller. The automatic chemical solution mixing device, from top to bottom, includes a neutral distilled water tank, two or more chemical reagent tanks, a solenoid valve, a partition plate, a mixing tank, and a stirring paddle. The neutral distilled water tank and the chemical reagent tanks are arranged side-by-side. Both the neutral distilled water tank and the chemical reagent tanks are connected to the mixing tank via solenoid valves and connecting pipes. The solenoid valve on the partition plate is positioned above the mixing tank, and the partition plate has a through-hole in the middle to allow the connecting pipes to pass through. The mixing tank is connected to the water / air channel of the normal loading head of the shear box via the chemical water pump and the chemical water pressure controller.

[0010] The temperature circulation system includes an outdoor unit, an indoor unit, a temperature circulation environment chamber, and a detachable insulation sleeve; the indoor unit includes an evaporator / condenser, a fan, a thermal expansion valve, a controller, a water receiving tray, and water pipes. The evaporator / condenser is arranged close to the outer wall of the shear box. The temperature circulation environment chamber, composed of an outer wall, an insulation layer, and an inner wall, is located outside the evaporator / condenser. There are two detachable insulation sleeves, located at the connection points of the reaction column and the horizontal loading electric cylinder, respectively.

[0011] The vibration loading system includes a cylinder, a striking block, an anti-rotation rod, an anti-rotation rod connecting rod, and a connecting base; the vibration loading system is fixed to the left side of the fixed base of the pressure shear system, the cylinder is connected to the air compressor through the connecting base at the rear end, the anti-rotation rod connecting rod and the anti-rotation rod are provided at the front of the cylinder, and the striking block is located at the front end of the cylinder and close to the left side of the upper shear box;

[0012] The data monitoring and intelligent control system includes sensors, data acquisition devices, and a computer; the sensors include a displacement sensor located in the shear box, a pH / ion meter located in the liquid preparation tank, a temperature sensor located in the three specimen joints, and a load sensor located at the rear end of the cylinder.

[0013] Furthermore, the normal loading electric cylinder of the compression shear system is used to apply the normal load, the horizontal loading electric cylinder is used to apply the shear load, and the reaction column is used to fix the upper shear box and constrain its deformation in the shear direction.

[0014] Furthermore, a silicone pad is provided on the lower surface of the normal loading pad.

[0015] Furthermore, the mixing tank is made of transparent organic fiberglass and has scale lines on the outer wall indicating its volume. The bottom of the mixing tank is equipped with a drain hole for discharging waste liquid after the test.

[0016] Furthermore, the outer wall of the temperature cycling chamber is made of coated metal plate material, the insulation layer is made of rigid polyurethane foam material, and the inner wall is made of high-impact polystyrene material. The temperature cycling chamber has an insulation range of -10°C to 70°C.

[0017] Moreover, the vibration loading system and the reaction column are installed in close proximity, and the reaction column is a sleeve-type structure that facilitates the installation of the vibration loading system.

[0018] A test method applicable to the THMC-B coupled soft rock shear rheology test system includes the following steps:

[0019] Step 1. Attach silicone gaskets to the surface of the rock sample for seepage prevention. After the gaskets are firmly attached, install the rock sample in the lower shear box. Align the upper and lower shear boxes and slowly lower the upper shear box until they fit tightly together.

[0020] Step 2. Install and debug the data monitoring sensors or instruments required for the test, and preload the shear box through the computer control system to ensure that the shear box is in full contact with the normal loading head and the horizontal loading head;

[0021] Step 3. Apply normal loading pressure to the design value according to the test plan. After the normal pressure stabilizes, apply shear loading pressure to the design value.

[0022] Step 4. Apply one or more fields of seepage field, chemical field, temperature field, and blasting disturbance according to the test plan:

[0023] The application of the seepage field refers to the continuous wet-dry cycle of water pressure and air pressure according to the test plan. The seepage water pressure is controlled to the design value through the pressure regulating valve to simulate the rainy season rainfall process. After the design time of seepage water pressure is reached, the pressure regulating valve is closed, and the air pressure is controlled to the design value through the air pressure regulating valve to simulate the drainage process of water in the dry season. The number of wet-dry cycles is determined according to the test plan and is applied evenly to each stage of loading before the destructive stage.

[0024] Chemical field application refers to preparing chemical solutions with different ion concentrations in a chemical reagent tank, using a computer control system to mix the concentrated chemical solutions of different ions in the chemical reagent tank in a mixing tank to obtain a chemical solution with multiple ions that meet the experimental design, and then pumping the chemical solution into the rock sample through a water / air channel; the concentration and type of each ion in the chemical solution are determined according to the experimental plan.

[0025] Applying a temperature field means first installing the indoor unit outside the shear box and the temperature circulation environment box outside the indoor unit, and then setting the upper and lower limits of the temperature, the circulation time and the number of cycles for the indoor unit and the temperature circulation environment box in the computer control system to simulate the temperature field.

[0026] Blasting disturbance application refers to setting the vibration frequency and vibration energy of the vibration loading system in the computer control system, and applying it at the designed time according to the test plan to simulate the effect of blasting disturbance.

[0027] Step 5. After the rock sample deformation rate reaches the design requirements, apply the next level of shear loading pressure, and repeat the operations of Step 3 and Step 4 until the rock sample fails and the loading is stopped. Record the test data.

[0028] Step 6. Disassemble and properly preserve the damaged rock samples, and clean and maintain the test system.

[0029] Compared with the prior art, the present invention has the following advantages:

[0030] (1) The experimental system of this invention can realize THMC-B multi-field coupling of seepage field, chemical field, temperature field and blasting disturbance under stress field loading in small-scale indoor shear creep tests, thereby simulating the engineering geological environment of soft rock. Through the coordinated cooperation of the compression-shear system, seepage system, chemical erosion system, temperature cycling system, vibration loading system and data monitoring and intelligent control system, soft rock mechanical experiments under different coupling conditions can be realized. At the same time, corresponding experimental methods are provided. The operation is simple, the degree of automation is high and the experimental efficiency is high. The test process does not require disassembling the shear box, providing an experimental means for the study of soft rock shear rheological characteristics and failure evolution law.

[0031] (2) The compression-shear system of the present invention is used to simulate stress field, and can apply normal load and shear load. The reaction column can fix the shear box to constrain its deformation in the shear direction.

[0032] (3) The seepage system of the present invention is used to simulate the seepage field, including a water pressure loading device and a gas pressure loading device. It can continuously circulate water pressure and gas pressure according to the test plan to simulate the rainy season rainfall process and the dry season water drainage process. At the same time, silicone gaskets and servo force control are used to ensure the sealing effect and effectively prevent the seepage liquid from leaking out. The test system can withstand the cyclic seepage pressure of 0~5MPa.

[0033] (4) The chemical erosion system of the present invention is used to simulate a chemical field. The solution preparation tank is made of organic fiberglass, which has a high degree of visualization. The internal pH online monitor and ion concentration detector can monitor the changes in ion concentration in real time. With multiple chemical reagent boxes, it is convenient to control and adjust the chemical field test conditions (such as ion concentration, ion type, etc.) in real time. All components of the test system involving the chemical field are made of acid and alkali corrosion resistant materials or coating materials with acid and alkali corrosion resistant materials, which effectively avoids equipment damage and test result errors.

[0034] (5) The temperature cycling system of the present invention is used to simulate the temperature field and achieves more efficient and accurate control of different temperatures and cooling and heating processes through evaporators / condensers and temperature sensors; the temperature cycling environment chamber keeps the internal temperature of the sample constant and avoids errors in the test results due to the temperature difference between the inside and outside.

[0035] (6) The vibration loading system of the present invention is used to simulate blasting disturbance. It is connected to an air compressor and a cylinder is used to push the impact block to impact the shear box, simulating the disturbance effect of blasting vibration on the rock, and realizing the controllable adjustment of vibration frequency, vibration energy, etc.

[0036] (7) The data monitoring and intelligent control system of the present invention controls the operation of each system by computer, with a high degree of automation; and collects test data in real time through each sensor, which facilitates data processing and analysis. Attached Figure Description

[0037] Figure 1 This is an overall structural diagram of the experimental system of the present invention.

[0038] Figure 2 This is a schematic diagram of the connections between the various systems of the experimental system of this invention.

[0039] Figure 3 This is a cross-sectional schematic diagram of the shear box of the present invention.

[0040] Figure 4 This is a schematic diagram of the compression shearing system of the present invention.

[0041] Figure 5 This is a schematic diagram of the seepage system of the present invention.

[0042] Figure 6 This is a schematic diagram of the chemical erosion system of the present invention.

[0043] Figure 7 This is a top view schematic diagram of the chemical erosion system of the present invention.

[0044] Figure 8 This is a schematic diagram of the overall structure of the temperature circulation system of the present invention.

[0045] Figure 9 This is a schematic diagram of the internal unit of the temperature circulation system of the present invention.

[0046] Figure 10 This is a cross-sectional schematic diagram of the temperature cycling environment chamber of the temperature cycling system of the present invention.

[0047] Figure 11 This is a schematic diagram of the vibration loading system of the present invention.

[0048] Figure 12 This is a schematic diagram of the assembly of the vibration loading system of the present invention.

[0049] In the diagram: 1. Shear box; 11. Upper shear box; 111. Top plate; 112. Upper shear body; 113. Normal loading head; 114. Normal loading pad; 115. Water / air channel; 116. Specimen joint; 12. Lower shear box; 2. Compression shear system; 201. Normal loading electric cylinder; 202. Horizontal loading electric cylinder; 203. Reaction column; 204. Fixed base; 3. Seepage system; 31. Hydraulic loading device; 311. Water 312. Pump; 313. Neutral distilled water tank; 314. Accumulator; 315. High-pressure water pipe; 316. Water pressure regulating valve; 317. Fine-tuning rod; 318. Water stop valve; 319. Pressure gauge; 32. Flow meter; 320. Pneumatic loading device; 321. Air compressor; 322. Pneumatic pressure regulating valve; 323. Pressure gauge; 4. Chemical etching system; 401. Drain hole; 412. Automatic chemical solution proportioning device; 413. Neutral distilled water tank; 412. Chemical reagent box; 413. Solenoid valve; 414. Isolation plate; 415. Solution mixing tank; 416. Stirring paddle; 42. Chemical water pump; 43. Chemical water pressure controller; 5. Temperature circulation system; 51. Outdoor unit; 52. Indoor unit; 521. Evaporator / condenser; 522. Fan; 523. Thermal expansion valve; 524. Controller; 525. Water tray; 526. Water pipe; 53. Temperature circulation environment chamber; 531. 532. Outer wall; 533. Insulation layer; 534. Inner wall; 555. Removable insulation sleeve; 6. Vibration loading system; 601. Cylinder; 602. Impact block; 603. Anti-rotation rod; 604. Anti-collision rod connecting rod; 605. Connecting base; 7. Data monitoring and intelligent control system; 701. Displacement sensor; 702. pH / ion meter; 703. Temperature sensor; 704. Load sensor; 71. Data acquisition device; 72. Computer. Detailed Implementation

[0050] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. However, the scope of the present invention is not limited to the following embodiments.

[0051] A THMC-B coupled rock shear rheology testing system, such as Figure 1 and Figure 2 As shown, it includes a shear box 1, a compression shear system 2, a seepage system 3, a chemical erosion system 4, a temperature circulation system 5, a vibration loading system 6, and a data monitoring and intelligent control system 7.

[0052] like Figure 3As shown, the shear box 1 includes an upper shear box 11 and a lower shear box 12. The upper shear box 11 includes a top plate 111, an upper shear body 112, a normal loading head 113, a normal loading pad 114, a water / air channel 115, and a sample connector 116. The top plate of the upper shear box 11 has a circular through hole. The normal loading head 113 passes through the circular through hole and abuts against the normal loading pad 114. A water / air channel 115 is provided in the normal loading head 113. The normal loading pad has three equally spaced water / air channels, each with a sample connector 116 installed. The water / air channels of the normal loading head extend downwards to connect with the three water / air channels in the normal loading pad. A thin silicone gasket 8 is provided on the lower surface of the normal loading pad 114 to prevent water / air and chemical solutions from seeping out from the sample connector 116. Furthermore, the inner wall coating material of the shear box, water / air channel 115, and silicone gasket are all materials that are resistant to acid and alkali corrosion and do not react with chemical ions, in order to avoid errors in test results under the influence of chemical fields.

[0053] like Figure 4 As shown, the compression-shear system 2 includes a fixed base 204, a normal loading electric cylinder 201 located directly above the shear box, a horizontal loading electric cylinder 202 located on the right side of the lower shear box, and a reaction column 203 located on the left side of the upper shear box. The fixed base is a hollow frame, and the shear box is located inside the fixed base. The fixed base has a through hole on its top, right, and left sides, and the three through holes are respectively used to fix the bases of the normal loading electric cylinder, the horizontal loading electric cylinder, and the reaction column. The normal loading electric cylinder of the compression-shear system is used to apply normal loads, the horizontal loading electric cylinder is used to apply shear loads, and the reaction column is used to fix the upper shear box and constrain its deformation in the shear direction.

[0054] like Figure 5 As shown, the seepage system 3 includes a water pressure loading device 31 and a pneumatic pressure loading device 32. The water pressure loading device 31 includes a water pump 311, a neutral distilled water tank 312, a high-pressure water pipe 314, an accumulator 313 installed on the high-pressure water pipe, a water pressure regulating valve 315, a fine-tuning rod 316, a water stop valve 317, a pressure gauge 318, and a flow meter 319. The pneumatic pressure loading device 32 includes an air compressor 321, a pneumatic pressure regulating valve 322, and a pressure gauge 323. Both the water pressure loading device 31 and the pneumatic pressure loading device 32 are connected to the shear box 1 through the water / air channel 115.

[0055] like Figure 6 , Figure 7As shown, the chemical erosion system 4 includes an automatic chemical solution mixing device 41, a chemical water pump 42 located below the automatic chemical solution mixing device, and a chemical water pressure controller 43; the automatic chemical solution mixing device 41 includes a neutral distilled water tank 411, a chemical reagent tank 412, a solenoid valve 413, an isolation plate 414, a solution mixing tank 415, and a stirring paddle 416. A neutral distilled water tank and a chemical reagent tank are arranged side by side. There are multiple chemical reagent tanks, each equipped with different high-concentration chemical reagents for preparing chemical solutions under different ion concentrations and pH conditions. Both the neutral distilled water tank and the chemical reagent tank are connected to the solution preparation tank via solenoid valves and connecting pipes. The position of the solenoid valve on the isolation plate is restricted to the top of the solution preparation tank, and the middle of the isolation plate has a through hole for the connecting pipe to pass through. The solution preparation tank 414 is connected to the shear box 1 via a water / gas channel. The solution preparation tank is made of transparent organic fiberglass material and has graduations on the outer wall to indicate the volume, which is used to check the preparation of chemical solutions and to facilitate cleaning after the experiment. The bottom of the solution preparation tank is equipped with a drain hole 401 for discharging waste liquid after the experiment. The stirring paddle allows the solution preparation tank to both stir the solution and serve as a cleaning device.

[0056] like Figure 8 , Figure 9 , Figure 10 As shown, the temperature circulation system 5 includes an outdoor unit 51, an indoor unit 52, a temperature circulation environment chamber 53, and a detachable insulation sleeve 54; the indoor unit 52 includes an evaporator / condenser 521 for heating / cooling conditions, a fan 522, a thermal expansion valve 523, a controller 524, a water receiving tray 525, and water pipes 526; the evaporator / condenser 521 is arranged close to the outer wall of the shear box 1; the temperature circulation environment chamber 53 is composed of an outer wall 531, an insulation layer 532, and an inner wall 533. Located outside the evaporator / condenser 521; the detachable insulation sleeve 54 is located at the connection of the reaction column 203 and the connection of the horizontal loading electric cylinder 202, and is used to provide the temperature environment required for the sample; the outer wall 531 of the temperature cycling environment chamber is made of coated metal plate material, the insulation layer 532 is made of rigid polyurethane foam material, and the inner wall 533 is made of high impact polystyrene material. The insulation range of the temperature cycling environment chamber is -10°~70°, and it is used for thermal insulation during the operation of the temperature cycling system.

[0057] like Figure 11 , Figure 12As shown, the vibration loading system 6 includes a cylinder 601, a striking block 602, an anti-rotation rod 603, an anti-rotation rod connecting rod 604, and a connecting base 605. The vibration loading system is fixed to the left side of the fixed base of the compression shear system. The cylinder is connected to the air compressor through the connecting base at the rear end. An anti-rotation rod connecting rod and an anti-rotation rod are set at the front of the cylinder. The striking block is located at the front end of the cylinder and near the left side of the upper shear box. The striking block 602 is made of high-strength alloy steel to avoid deformation after multiple cycles of testing and to ensure the accuracy of the impact force. The anti-rotation rod 603 is used to ensure that the cylinder will not deflect during high-frequency movement. The vibration loading system pushes the striking block to impact the shear box 1 through the cylinder, which can more realistically simulate the disturbance effect of blasting vibration on the rock. It can achieve vibration loading with a vibration frequency of 0-10Hz, a vibration frequency accuracy of ±0.1Hz, a vibration load of 0-300N, and a vibration load accuracy of ±1N. Since the installation positions of the vibration loading system and the reaction column are close, a sleeve-type reaction column that is easy to install with the vibration loading system is adopted to solve the problem that the existing reaction column cannot be matched with the vibration loading system.

[0058] The data monitoring and intelligent control system 7 includes sensors, a data acquisition device 71, and a computer 72. The sensors include a displacement sensor 701, a pH / ion meter 702, a temperature sensor 703, and a load sensor 704. The displacement sensor 701 is located in the shear box to monitor shear displacement and normal displacement. The pH / ion meter 702 is located in the solution preparation tank to monitor changes in pH and various ion concentrations of the chemical solution in the solution preparation tank 415. The temperature sensor 703 is located in the three specimen joints 116 to monitor the temperature of the specimen. The load sensor 704 is located at the rear end of the cylinder to monitor the impact force. The computer 72 is used for intelligent input and control of chemical field, temperature cycle, and vibration wave parameters.

[0059] The following examples illustrate a test method suitable for the THMC-B coupled soft rock shear rheology test system:

[0060] Step 1. First, prepare a rectangular rock sample with dimensions of 150mm × 75mm × 75mm. Drill three cylindrical holes of 8mm diameter and 37.5mm depth at equal intervals on the top of the rock sample. The flatness error of the end face should not exceed 0.01mm. Then, use glue to attach silicone gaskets 8 to the surface of the rock sample for seepage prevention. After attaching, leave it for 12 hours and check whether it is firmly attached. After it is firmly attached, install the rock sample in the lower shear box 12. Then, align the upper shear box 11 with the lower shear box 12 and slowly lower the upper shear box 11 until the upper and lower shear boxes 12 are tightly fitted together.

[0061] Step 2. Install and debug the data monitoring sensors or instruments required for the test, and then preload through the computer control system. The preload adopts a constant displacement loading method to make the shear box 1 fully contact the normal loading head 113 and the horizontal loading head. The preload rate is 0.001~0.01mm / s, and the loading stops when the target force reaches 0.5KN.

[0062] Step 3. Set the test parameters and acquisition parameters in the computer, including axial and radial loading methods, loading rates, target values, acquisition frequencies, etc.; after setting, clear the force, displacement, time, and other data to zero. Use a constant displacement loading method, apply the normal loading pressure to the design value according to the test plan, and after the normal pressure stabilizes, apply the shear loading pressure to the design value. Set the force loading rate to 0.05 kN / s.

[0063] Step 4. Apply one or more fields of seepage field, chemical field, temperature field, and blasting disturbance according to the test plan. In this embodiment, the single or multiple fields are applied after the creep rate of the rock sample has stabilized in each stage of loading before the failure level:

[0064] Seepage field application: According to the test plan, water pressure and air pressure are continuously circulated, divided into two parts. The seepage water pressure is controlled to the design value through water pressure regulating valve 315 to simulate the rainy season rainfall process. After reaching the design time for seepage water pressure, water pressure regulating valve 315 is closed, and air pressure is controlled to the design value through air pressure regulating valve 322 to simulate the dry season water drainage process. The single wet-dry cycle time is set to be greater than or equal to 5 hours, and the seepage water / air pressure is 0~5MPa. The number of wet-dry cycles is determined according to the test plan and is uniformly applied to each stage of loading before the destructive stage.

[0065] Chemical field application: Concentrated chemical solutions with different ion concentrations are prepared in chemical reagent tank 412. Using a computer control system, the concentrated chemical solutions with different ions in chemical reagent tank 412 are mixed in a mixing tank to obtain a chemical solution containing multiple ions that meets the experimental design. The chemical solution is then pumped into the rock sample through water / air channel 115. The concentration and type of each ion in the chemical solution are determined according to the experimental plan.

[0066] Temperature field application: Install the indoor unit 52 outside the shear box 1, and install the temperature cycling environment chamber 53 outside the indoor unit 52. Set parameters such as upper and lower temperature limits, cycle time, and number of cycles in the computer control system to intelligently apply the temperature field.

[0067] Blasting disturbance application: Parameters such as vibration frequency and vibration energy are set in the computer control system and applied at the designed time points according to the test plan to simulate the effect of blasting disturbance.

[0068] Step 5. Once the rock sample deformation rate reaches the design requirement, i.e., the rock sample deformation rate is less than 0.01 mm / h and the stabilization time is not less than 1 day, apply the next level of shear loading pressure according to the test plan, repeat the operation of S3-S4 until the rock sample is destroyed, stop loading, and save the test data in time.

[0069] Step 6. Using computer 72, remove the shear load, normal load, temperature cycling environment chamber 53, internal unit 52 and other system modules in sequence. Then lift the shear box 11, take out the rock sample damaged by shearing and preserve it properly. Finally, clean the shear box 1, chemical reagent box 412 and other components, and perform equipment maintenance.

[0070] In summary, the THMC-B coupled soft rock shear rheology testing system and method described in this invention have the following advantages:

[0071] (1) The experimental system of this invention can realize THMC-B multi-field coupling of seepage field, chemical field, temperature field and blasting disturbance under stress field loading in small-scale indoor shear creep tests, thereby simulating the engineering geological environment of soft rock. Through the coordinated cooperation of the compression-shear system, seepage system, chemical erosion system, temperature cycling system, vibration loading system and data monitoring and intelligent control system, soft rock mechanical experiments under different coupling conditions can be realized. At the same time, corresponding experimental methods are provided. The operation is simple, the degree of automation is high and the experimental efficiency is high. The test process does not require disassembling the shear box, providing an experimental means for the study of soft rock shear rheological characteristics and failure evolution law.

[0072] (2) The compression-shear system of the present invention is used to simulate stress field, and can apply normal load and shear load. The reaction column can fix the shear box to constrain its deformation in the shear direction.

[0073] (3) The seepage system of the present invention is used to simulate the seepage field, including a water pressure loading device and a gas pressure loading device. It can continuously circulate water pressure and gas pressure according to the test plan to simulate the rainy season rainfall process and the dry season water drainage process. At the same time, silicone gaskets and servo force control are used to ensure the sealing effect and effectively prevent the seepage liquid from leaking out. The test system can withstand the cyclic seepage pressure of 0~5MPa.

[0074] (4) The chemical erosion system of the present invention is used to simulate a chemical field. The solution preparation tank is made of organic fiberglass, which has a high degree of visualization. The internal pH online monitor and ion concentration detector can monitor the changes in ion concentration in real time. With multiple chemical reagent boxes, it is convenient to control and adjust the chemical field test conditions (such as ion concentration, ion type, etc.) in real time. All components of the test system involving the chemical field are made of acid and alkali corrosion resistant materials or coating materials with acid and alkali corrosion resistant materials, which effectively avoids equipment damage and test result errors.

[0075] (5) The temperature cycling system of the present invention is used to simulate the temperature field and achieves more efficient and accurate control of different temperatures and cooling and heating processes through evaporators / condensers and temperature sensors; the temperature cycling environment chamber keeps the internal temperature of the sample constant and avoids errors in the test results due to the temperature difference between the inside and outside.

[0076] (6) The vibration loading system of the present invention is used to simulate blasting disturbance. It is connected to an air compressor and a cylinder is used to push the impact block to impact the shear box, simulating the disturbance effect of blasting vibration on the rock, and realizing the controllable adjustment of vibration frequency, vibration energy, etc.

[0077] (7) The data monitoring and intelligent control system of the present invention controls the operation of each system by computer, with a high degree of automation; and collects test data in real time through each sensor, which facilitates data processing and analysis.

Claims

1. A THMC-B coupled soft rock shear rheology testing system, comprising at least a compression-shear system and a shear box disposed within the compression-shear system. The shear box consists of an upper shear box composed of a top plate, an upper shear body, a normal loading head, a normal loading pad, a water / air channel, and a specimen joint, and a lower shear box disposed at the bottom of the upper shear box. The top plate of the upper shear box has a circular through hole through which the normal loading head passes and abuts against the normal loading pad. A water / air channel is disposed in the normal loading head. The normal loading pad has three equally spaced water / air channels, each equipped with a specimen joint. The water / air channel of the normal loading head extends downward to connect with the three water / air channels in the normal loading pad. The system is characterized in that: It also includes a compression-shear system, a seepage system, a chemical erosion system, a temperature cycling system, a vibration loading system, and a data monitoring and intelligent control system; The compression shearing system includes a fixed base, a normal phase loading electric cylinder located directly above the shear box, a horizontal loading electric cylinder located on the right side of the lower shear box, and a reaction column located on the left side of the upper shear box. The fixed base is a hollow frame, and the shear box is located inside the fixed base. The fixed base has a through hole on the top, right, and left sides, and the three through holes are respectively used to fix the bases of the normal phase loading electric cylinder, the horizontal loading electric cylinder, and the reaction column. The seepage system includes a water pressure loading device and a pneumatic pressure loading device. The water pressure loading device includes a neutral distilled water tank, a water pump, a high-pressure water pipe, a fine-tuning rod on the high-pressure water pipe, an accumulator, a water pressure regulating valve, a water stop valve, a pressure gauge, and a flow meter. The pneumatic pressure loading device includes an air compressor, a pneumatic pressure regulating valve, and a pressure gauge. The high-pressure water pipe outlet of the water pressure loading device and the air pipe outlet of the pneumatic pressure loading device are both connected to the water / air channel of the normal loading head of the shear box. The chemical erosion system includes an automatic chemical solution mixing device, a chemical water pump located below the automatic chemical solution mixing device, and a chemical water pressure controller. The automatic chemical solution mixing device, from top to bottom, includes a neutral distilled water tank, two or more chemical reagent tanks, a solenoid valve, a partition plate, a mixing tank, and a stirring paddle. The neutral distilled water tank and the chemical reagent tanks are arranged side-by-side. Both the neutral distilled water tank and the chemical reagent tanks are connected to the mixing tank via solenoid valves and connecting pipes. The solenoid valve on the partition plate is positioned above the mixing tank, and the partition plate has a through-hole in the middle to allow the connecting pipes to pass through. The mixing tank is connected to the water / air channel of the normal loading head of the shear box via the chemical water pump and the chemical water pressure controller. The temperature circulation system includes an outdoor unit, an indoor unit, a temperature circulation environment chamber, and a detachable insulation sleeve; the indoor unit includes an evaporator / condenser, a fan, a thermal expansion valve, a controller, a water receiving tray, and water pipes. The evaporator / condenser is arranged close to the outer wall of the shear box. The temperature circulation environment chamber, composed of an outer wall, an insulation layer, and an inner wall, is located outside the evaporator / condenser. There are two detachable insulation sleeves, located at the connection points of the reaction column and the horizontal loading electric cylinder, respectively. The vibration loading system includes a cylinder, a striking block, an anti-rotation rod, an anti-rotation rod connecting rod, and a connecting base; the vibration loading system is fixed to the left side of the fixed base of the pressure shear system, the cylinder is connected to the air compressor through the connecting base at the rear end, the anti-rotation rod connecting rod and the anti-rotation rod are provided at the front of the cylinder, and the striking block is located at the front end of the cylinder and close to the left side of the upper shear box; The data monitoring and intelligent control system includes sensors, data acquisition devices, and a computer; the sensors include a displacement sensor located in the shear box, a pH / ion meter located in the liquid preparation tank, a temperature sensor located in the three specimen joints, and a load sensor located at the rear end of the cylinder.

2. The THMC-B coupled soft rock shear rheology testing system according to claim 1, characterized in that: The normal loading electric cylinder of the compression shear system is used to apply the normal load, the horizontal loading electric cylinder is used to apply the shear load, and the reaction column is used to fix the upper shear box and constrain its deformation in the shear direction.

3. The THMC-B coupled soft rock shear rheology testing system according to claim 1, characterized in that: A silicone pad is provided on the lower surface of the normal loading pad block.

4. The THMC-B coupled soft rock shear rheology testing system according to claim 1, characterized in that: The mixing tank is made of transparent organic fiberglass and has scale lines on the outer wall to indicate its volume. The bottom of the mixing tank is equipped with a drain hole for discharging waste liquid after the test.

5. The THMC-B coupled soft rock shear rheology testing system according to claim 1, characterized in that: The outer wall of the temperature cycling chamber is made of coated metal plate, the insulation layer is made of rigid polyurethane foam, and the inner wall is made of high-impact polystyrene. The temperature range of the temperature cycling chamber is -10°C to 70°C.

6. The THMC-B coupled soft rock shear rheology testing system according to claim 1, characterized in that: The vibration loading system and the reaction column are installed in close proximity. The reaction column is a sleeve-type structure that facilitates the installation of the vibration loading system.

7. A THMC-B coupled soft rock shear rheology testing system according to any one of claims 1 to 6, characterized in that, The test method includes the following steps: Step 1. Attach silicone gaskets to the surface of the rock sample for seepage prevention. After the gaskets are firmly attached, install the rock sample in the lower shear box. Align the upper and lower shear boxes and slowly lower the upper shear box until they fit tightly together. Step 2. Install and debug the data monitoring sensors or instruments required for the test, and preload the shear box through the computer control system to ensure that the shear box is in full contact with the normal loading head and the horizontal loading head; Step 3. Apply normal loading pressure to the design value according to the test plan. After the normal pressure stabilizes, apply shear loading pressure to the design value. Step 4. Apply one or more fields of seepage field, chemical field, temperature field, and blasting disturbance according to the test plan: The application of the seepage field refers to the continuous wet-dry cycle of water pressure and air pressure according to the test plan. The seepage water pressure is controlled to the design value through the pressure regulating valve to simulate the rainy season rainfall process. After the design time of seepage water pressure is reached, the pressure regulating valve is closed, and the air pressure is controlled to the design value through the air pressure regulating valve to simulate the drainage process of water in the dry season. The number of wet-dry cycles is determined according to the test plan and is applied evenly to each stage of loading before the destructive stage. Chemical field application refers to preparing chemical solutions with different ion concentrations in a chemical reagent tank, using a computer control system to mix the concentrated chemical solutions of different ions in the chemical reagent tank in a mixing tank to obtain a chemical solution with multiple ions that meet the experimental design, and then pumping the chemical solution into the rock sample through a water / air channel; the concentration and type of each ion in the chemical solution are determined according to the experimental plan. Applying a temperature field means first installing the indoor unit outside the shear box and the temperature circulation environment box outside the indoor unit, and then setting the upper and lower limits of the temperature, the circulation time and the number of cycles for the indoor unit and the temperature circulation environment box in the computer control system to simulate the temperature field. Blasting disturbance application refers to setting the vibration frequency and vibration energy of the vibration loading system in the computer control system, and applying it at the designed time according to the test plan to simulate the effect of blasting disturbance. Step 5. After the rock sample deformation rate reaches the design requirements, apply the next level of shear loading pressure, and repeat the operations of Step 3 and Step 4 until the rock sample fails and the loading is stopped. Record the test data. Step 6. Disassemble and properly preserve the damaged rock samples, and clean and maintain the test system.

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