Rock mass deterioration test system and test method for simulating dynamic change of water level

Abstract

The invention belongs to the technical field of rock-soil tests, and particularly discloses a rock mass deterioration test system and test method for simulating water level dynamic change, and the system comprises a single-shaft hydraulic servo control subsystem, a water-stop sheet lifting subsystem, a water flow control subsystem, a drying subsystem, a temperature control subsystem and an acoustic subsystem; the single-shaft hydraulic servo control subsystem comprises a servo hydraulic pump and a core holder; the water-stop sheet lifting subsystem comprises a water-stop sheet and a lifting assembly; the water flow control subsystem comprises a circulating water storage tank, a constant-pressure constant-flow water pump, a third check valve, a flow meter and a fourth check valve; and the acoustic subsystem is used for measuring the dynamic elastic modulus of the rock mass by transmitting ultrasonic pulses and receiving reflected P and S waves, so that the real-time dynamic characterization of the damage degree in the rock degradation process is realized. The device and the method can simulate a rock degradation scene under a complex environment condition, especially under a dynamic water level change condition, and realize simulation of a damage condition in a rock mass under an in-situ stress state.

Description

Technical Field

[0001] The invention relates to the technical field of rock mass degradation testing, and in particular to a rock mass degradation test system and a test method for simulating dynamic changes in water levels. Background Art

[0002] As the water level in the Three Gorges Reservoir periodically fluctuates between 145 and 175 meters, a drawdown zone with a vertical drop of 30 meters is formed. The water level and environmental conditions (stress, temperature, water flow erosion, etc.) of the rock mass in the drawdown zone change periodically, causing rapid deterioration of the slope rock mass and further inducing numerous geological disasters.

[0003] The environment of rock degradation is complex. The main causes of degradation are dry-hot-cold-wet cycles caused by dynamic changes in water levels, water erosion, overlying rock pressure, and temperature changes. In view of the above reasons, in-depth research on the degradation process of rock in complex environments can provide a theoretical basis for taking effective prevention and control measures.

[0004] Chinese patent application CN112198055A discloses a device and method for simulating rock degradation under dynamic water-stress coupling, the device includes a dynamic water circulation system, a diversion system and a loading system, and can simulate the influence of complex dynamic water conditions and stress conditions on rock mass.

[0005] Chinese patent application CN114034629A discloses a system and method for monitoring rock mass damage during dry-wet cycles in a chemical corrosion environment. The device includes a dry-wet cycle test box, a chemical solution configuration container, a dry heat source supply box, and a host computer configured with a damage degree calculation program. The damage of the rock mass can be monitored during the dry-wet cycle process.

[0006] Chinese patent application CN111948241A discloses a test device and method for simulating the degradation process of rock mass in the drawdown zone, which includes a test box, a nuclear magnetic resonance signal processor, a flow controller, an air pressurization and heating system, a liquid nitrogen system, a water level control system, a discharge system and a data processing system. It can simulate the changes in the mechanical properties of rock mass in the drawdown zone under different water levels, different pressures and different temperatures.

[0007] Chinese patent application CN108613874A discloses a triaxial loading water-rock interaction experimental device, which includes a temperature control system, a water pressure control system, an axial pressure control system, a time control system and a permeable pad. The device can adjust and control the water pressure, temperature, axial pressure and saturation time during the saturation process, thereby simulating the behavior of the rock mass under different environments.

[0008] The existing technology has the following defects:

[0009] ① There is a lack of simulation of rock degradation scenarios under complex environmental conditions (stress-water level-water flow-temperature), especially under dynamic water level change conditions (dynamic rise and fall of water level, water flow scouring, and water pressure effects).

[0010] ② There is a lack of equipment and methods for in-situ testing of the degree of damage during rock degradation. The existing testing methods require the removal of the rock for testing, which will inevitably change the degree of internal damage and cannot simulate the damage inside the rock mass under the in-situ stress state. Summary of the invention

[0011] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a rock degradation test system and test method that simulates dynamic changes in water levels, so as to simulate rock degradation scenarios under complex environmental conditions (stress-water level-water flow-temperature), especially under dynamic water level change conditions (dynamic rise and fall of water level, water flow scouring, water pressure), and realize the simulation of the damage inside the rock mass under in-situ stress state.

[0012] In order to achieve the above object, the present invention adopts the following technical scheme:

[0013] In a first aspect, the present invention provides a rock degradation test system for simulating dynamic changes in water level, comprising a single-axis hydraulic servo control subsystem, a baffle lifting subsystem, a water flow control subsystem, a drying subsystem, a temperature control subsystem and an acoustic subsystem;

[0014] The single-axis hydraulic servo control subsystem includes a servo hydraulic pump and a core holder, wherein the core holder is used to hold a rock sample, the core holder is partially embedded in a flushing water tank, the rock sample is located in the flushing water tank, and the servo hydraulic pump is connected to the core holder to apply pressure to the rock sample;

[0015] The water barrier lifting subsystem includes a water barrier and a lifting assembly; wherein the water barrier is arranged in the flushing water tank, dividing the flushing water tank into a saturated area and a dry area, and the lifting assembly is connected to the water barrier to drive the water barrier to move up and down in the flushing water tank;

[0016] The water flow control subsystem includes a circulating water storage tank, a constant pressure and constant flow water pump, a third check valve and a flow meter, and a fourth check valve; the circulating water storage tank is connected to the flushing water tank through a first pipe and a second pipe, the first pipe is provided with a constant pressure and constant flow water pump, a third check valve and a flow meter, and the second pipe is provided with the fourth check valve;

[0017] The drying subsystem is used to dry the rock sample;

[0018] The temperature control subsystem is used to regulate the temperature in the flushing tank;

[0019] The acoustic subsystem measures the dynamic elastic modulus of the rock mass by emitting ultrasonic pulses and receiving reflected P and S waves, thereby achieving real-time dynamic characterization of the degree of damage during rock degradation.

[0020] Furthermore, the core clamp includes a hydraulic cylinder, a guide rail, a loading column and a pressure plate; the servo hydraulic pump is connected to the hydraulic cylinder, the hydraulic cylinder is connected to the loading column, the loading column is connected to the pressure plate, and the flushing water tank is installed on the guide rail.

[0021] Furthermore, the lifting assembly includes a screw rod, a nut, a connecting rod and a silicone sealing strip; the water-blocking plate, the screw rod and the nut are each provided in two numbers, the connecting rod is connected to the two screw rods through a gear structure so that they rotate synchronously, the nut is assembled on the screw rod, and when the screw rod rotates, the meshing action of the thread and the nut pushes the screw rod up and down, thereby driving the water-blocking plate to move in a vertical direction, realizing the simulation of the dynamic change of the water level, and a silicone sealing strip is respectively installed at the contact position between the screw rod and the flushing trough and the contact position between the water-blocking plate and the flushing trough.

[0022] Furthermore, the drying subsystem includes a hot air blower and a waste liquid collector. The hot air blower is connected to the air inlet through a pipe to send constant temperature cross-flow gas into the flushing water tank through the air inlet to heat or dry the rock sample. After the gas is fully in contact with the rock sample, it enters the waste liquid collector through the exhaust port and the pipe; the pipe connecting the hot air blower and the waste liquid collector is respectively equipped with a first check valve and a second check valve.

[0023] Furthermore, the temperature control subsystem includes a temperature control element and a thermometer, the thermometer is arranged in the flushing water tank, and the thermometer is electrically connected to the temperature control element.

[0024] Furthermore, the acoustic subsystem includes a first ultrasonic probe, a second ultrasonic probe and a data acquisition and processing system; wherein, the first ultrasonic probe and the second ultrasonic probe are arranged at both ends of the rock sample, and the first ultrasonic probe and the second ultrasonic probe are both connected to the data acquisition and processing system, and the data acquisition and processing system is used to control the first ultrasonic probe and the second ultrasonic probe to emit ultrasonic pulses and receive reflected P and S waves to measure the dynamic elastic modulus of the rock mass, thereby realizing real-time dynamic characterization of the degree of damage during rock degradation.

[0025] In a second aspect, the present invention provides a rock degradation test method for simulating dynamic changes in water level, based on the rock degradation test system for simulating dynamic changes in water level described in the first aspect, the method comprises:

[0026] Step 1: Turn on the temperature control element in advance to heat the liquid in the circulating water storage tank to the rated temperature, install the completely dried rock sample in the core holder, and place the core holder in the flushing water tank;

[0027] Step 2, start the servo hydraulic pump to apply a set axial pressure to the rock sample;

[0028] Step 3, turning on the first ultrasonic probe and the second ultrasonic probe, transmitting a pulse signal and receiving the reflected P and S waves, and obtaining the propagation speed of the P and S waves in the rock mass by recording the propagation time, thereby obtaining the lossless dynamic elastic modulus of the rock;

[0029] Step 4, rotate the linkage rod, adjust the position of the baffle plate through the screw rod, and lower the baffle plate to the bottom of the rock sample;

[0030] Step 5, turn on the constant pressure and constant flow water pump to deliver the liquid with constant temperature, constant pressure and / or constant flow into the saturated area at the bottom of the flushing water tank through the liquid inlet; turn on the hot air blower to deliver the constant temperature gas into the drying area at the top of the flushing water tank through the air inlet;

[0031] Step 6: After the gas and liquid rates in the flushing tank are stable, control the linkage rod to raise the baffle to the top of the rock sample at a rated rate, and then lower it at the same rated rate;

[0032] Step 7: When the baffle returns to the bottom of the rock sample, drain the residual liquid in the flushing tank, turn on the hot air blower and set the drying temperature, dry the sample for 24 hours, and repeat step 3 to test the rock damage dynamic elastic modulus E. n ;

[0033] Step 8, repeat steps 5 to 7 to obtain the damage characteristics of the rock sample under different cycle numbers, thereby revealing the degradation law of the rock sample.

[0034] Furthermore, in step 3 and step 7, the dynamic elastic modulus is obtained by the following formula:

[0035]

[0036] In the formula, E i is the dynamic elastic modulus, where i = 0 or n, n>0, representing the i-th water level dynamic cycle, when i = 0, E0 is the lossless elastic modulus, when i = n, E n is the damage elastic modulus under the nth water level dynamic cycle, ρ is the density of the rock sample, v pi 、v si are the propagation rates of P and S waves in rocks under the i-th water level dynamic cycle.

[0037] Furthermore, according to the lossless dynamic elastic modulus E0 and the damaged dynamic elastic modulus E nDetermine the damage variable as shown in the following formula:

[0038]

[0039] Where D is the damage variable.

[0040] Compared with the prior art, the present invention has the following beneficial effects:

[0041] 1. Ability to simulate the impact of environmental stress, temperature, water flow and water level changes on rock degradation process.

[0042] 2. Ultrasonic probes can be used to achieve in-situ non-destructive measurement of rock sample damage variables.

[0043] 3. Separating the saturated system from the dry system by raising and lowering the baffle can better fit the actual environment and realize the simulation of the entire process of water level changes. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0045] Figure 1 A schematic diagram of the overall structure of a rock degradation test system for simulating dynamic changes in water levels provided in an embodiment of the present invention.

[0046] Figure 2 A schematic diagram of the structure of a core holder in a rock degradation test system simulating dynamic changes in water level provided by an embodiment of the present invention.

[0047] Figure 3 A schematic structural diagram of a water-blocking plate in a rock degradation test system simulating dynamic changes in water level provided in an embodiment of the present invention.

[0048] Figure 4 A flow chart of a rock degradation test method for simulating dynamic changes in water levels provided in an embodiment of the present invention.

[0049] Description of reference numerals:

[0050] 1-hot air blower, 2-first check valve, 3-air inlet, 4-exhaust port, 5-second check valve, 6-waste liquid collection device, 7-constant pressure and constant flow water pump, 8-flow meter, 9-thermometer, 10-third check valve, 11-liquid inlet, 12-water pressure gauge, 13-liquid outlet, 14-fourth check valve, 15-circulating water storage tank, 16-temperature control element, 17-water baffle, 18-screw rod, 19-link rod, 20-servo hydraulic pump, 21-axial pressure gauge, 22-hydraulic cylinder, 23-pressing plate, 24-first ultrasonic probe, 25-rock sample, 26-second ultrasonic probe, 27-data acquisition and processing system, 28-flushing water tank, 29-nut, 30-guide rail, 31-loading column, 32-silicone sealing strip. DETAILED DESCRIPTION

[0051] The following describes the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict.

[0052] In the description of the present invention, unless otherwise specified, "plurality" means two or more than two; the orientations or positional relationships indicated by the terms "upper", "lower", "left", "right", "inner", "outer", "front end", "rear end", "head", "tail", etc. are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", "third", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance.

[0053] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0054] The present invention will now be further described with reference to the accompanying drawings.

[0055] Embodiment 1:

[0056] The present invention provides a rock degradation test system for simulating dynamic changes in water level. Figures 1 to 3 As shown, the rock degradation test system simulating dynamic changes in water level includes a single-axis hydraulic servo control subsystem, a baffle lifting subsystem, a water flow control subsystem, a drying subsystem, a temperature control subsystem and an acoustic subsystem.

[0057] The specific structure and functions of the six subsystems mentioned above will be described in detail below.

[0058] like Figure 1 As shown, the single-axis hydraulic servo control subsystem includes a servo hydraulic pump 20 and a core clamp 2. The core clamp 2 is used to clamp a rock sample 25. The core clamp 2 is partially embedded in a flushing water tank 28. The rock sample 25 is located in the flushing water tank 28. The servo hydraulic pump 20 is connected to the core clamp 2 to apply pressure to the rock sample 20.

[0059] Specifically, if Figure 2 As shown, the core holder 2 includes a hydraulic cylinder 22, a guide rail 30, a loading column 31 and a pressure plate 23; the servo hydraulic pump 20 is connected to the hydraulic cylinder 22, the hydraulic cylinder 22 is connected to the loading column 31, the loading column 31 is connected to the pressure plate 23, and the flushing tank 28 is installed on the guide rail 30

[0060] In the single-axis hydraulic servo control subsystem, the servo hydraulic pump 20 can provide an axial pressure of 0-200MPa, and can adjust the oil volume through the servo valve to stabilize the pressure at the target value, thereby simulating the stress environment of the rock mass. The core holder 2 includes the hydraulic cylinder 22, the guide rail 30, the loading column 31 and the pressure plate 23, which can be embedded in the flushing water tank (28), which is the main place where the water-rock interaction occurs; the servo hydraulic pump (20) feeds fluorine oil into the hydraulic cylinder (22) through the oil inlet pipe, and the hydraulic cylinder transmits the pressure to the loading column (31), and transmits it to the pressure plate (23) through the loading column to apply it on the rock mass (25). The axial pressure gauge (21) can observe its axial pressure change. Among them, the pressure plate 23 includes an upper and a lower pressure plate, and the upper and lower pressure plates can be disassembled to facilitate the installation of rock samples.

[0061] The baffle lifting subsystem includes a baffle 17 and a lifting assembly; wherein, the baffle 17 is arranged in the flushing trough 28, dividing the flushing trough 28 into a saturated area and a dry area, and the lifting assembly is connected to the baffle 17 to drive the baffle 17 to move up and down in the flushing trough 28.

[0062] Specifically, the lifting assembly includes a screw 18, a nut 29, a connecting rod 19 and a silicone sealing strip 32; the water-blocking plate 17, the screw 18 and the nut 29 are all set in two, and the connecting rod 19 is connected to the two screws 18 through a gear structure to make them rotate synchronously. The nut is assembled on the screw 18. When the screw 18 rotates, the meshing action of the thread and the nut 29 pushes the screw up and down, thereby driving the water-blocking plate 17 to move in the vertical direction to realize the simulation of the dynamic change of the water level. A silicone sealing strip 32 is installed at the contact position between the screw 18 and the flushing trough 28 and the water-blocking plate 17 and the flushing trough 28 to ensure that there will be no water leakage.

[0063] The water flow control subsystem includes a circulating water storage tank 15, a constant pressure and constant flow water pump 7, a third check valve 10, a flow meter 8 and a fourth check valve 14; the circulating water storage tank 15 is connected to the flushing water tank 28 through a first pipe and a second pipe, the first pipe is provided with a constant pressure and constant flow water pump 7, a third check valve 10 and a flow meter 8, and the second pipe is provided with a fourth check valve 14. The constant pressure and constant flow water pump 7 inputs the liquid into the flushing water tank 28 at a constant flow rate through the liquid inlet 11 connected to the flushing water tank 28, and the flow meter 8 and the water pressure gauge 12 embedded in the system can monitor the flow rate and water pressure of the water body in real time. The third check valve 10 and the fourth check valve 14 installed near the liquid inlet and outlet are used for monitoring and switching the water body.

[0064] The drying subsystem is used to dry the rock samples.

[0065] In some embodiments, the drying subsystem includes a hot air blower 1 and a waste liquid collector 6. The hot air blower 1 is connected to the air inlet 3 through a pipe to send constant temperature cross-flow gas through the air inlet into the flushing water tank to heat or dry the rock sample 25. After the gas is fully in contact with the rock sample, it enters the waste liquid collector through the exhaust port 4 through the pipe; the pipe connecting the hot air blower 1 and the waste liquid collector 6 is respectively equipped with a first check valve and a second check valve 5.

[0066] The temperature control subsystem is used to regulate the temperature in the flushing tank.

[0067] In some embodiments, the temperature control subsystem includes a temperature control element 16 and a thermometer 9, the thermometer 9 is disposed in the flushing water tank 28, and the thermometer 9 is electrically connected to the temperature control element 16. The temperature control element 16 regulates the temperature of the water in the flushing water tank 28, and observes its temperature changes in real time through the thermometer 9 embedded in the system. In addition, the outside of the flushing water tank 28 can be wrapped with insulation material to ensure that the temperature of the water inside is uniform.

[0068] The acoustic subsystem measures the dynamic elastic modulus of the rock mass by emitting ultrasonic pulses and receiving reflected P and S waves, thereby achieving real-time dynamic characterization of the degree of damage during rock degradation.

[0069] In some embodiments, the acoustic subsystem includes a first ultrasonic probe 24, a second ultrasonic probe 26 and a data acquisition and processing system 27; wherein the first ultrasonic probe 24 and the second ultrasonic probe 26 are arranged at both ends of the rock sample 25, and the first ultrasonic probe 24 and the second ultrasonic probe 26 are both connected to the data acquisition and processing system 27, and the data acquisition and processing system 27 is used to control the first ultrasonic probe 24 and the second ultrasonic probe 26 to emit ultrasonic pulses and receive reflected P and S waves to measure the dynamic elastic modulus of the rock mass, thereby realizing real-time dynamic characterization of the degree of damage during rock degradation.

[0070] Embodiment 2:

[0071] The embodiment of the present invention provides a rock degradation test method for simulating dynamic changes in water level. The rock degradation test method for simulating dynamic changes in water level is based on the rock degradation test device for simulating dynamic changes in water level as described in Example 1. Figure 4 As shown, the rock mass degradation test method simulating dynamic changes in water level is performed by the following steps:

[0072] Step 1: Open the temperature control element 16 in advance to heat the liquid in the circulating water storage tank 15 to the rated temperature, then install the completely dried rock sample 25 in the core holder, and place the core holder in the flushing water tank.

[0073] Step 2: Apply rated axial pressure to the rock sample 25 through the servo hydraulic pump 20 .

[0074] Step 3: Turn on the first ultrasonic probe 24 and the second ultrasonic probe 26, transmit pulse signals and receive the reflected P and S waves, and obtain the propagation speed of the P and S waves in the rock mass by recording the propagation time, thereby obtaining the lossless dynamic elastic modulus E0 of the rock. Dynamic elastic modulus E i Mainly obtained through the following formula, dynamic elastic modulus E i and P and S wave propagation speed v pi 、v si There is a corresponding functional relationship between them:

[0075]

[0076] In the formula, E i is the dynamic elastic modulus, where i = 0 or n, n>0, representing the i-th water level dynamic cycle, when i = 0, E0 is the lossless elastic modulus, when i = n, E n is the damage elastic modulus under the nth water level dynamic cycle, ρ is the density of the rock sample, v pi 、v si are the propagation rates of P and S waves in rocks under the i-th water level dynamic cycle.

[0077] Step 4: rotate the linkage rod 19, adjust the position of the baffle plate 17 through the screw rod 18, and lower the baffle plate to the bottom of the rock sample.

[0078] Step five, turn on the constant pressure and constant flow water pump 7, and send the constant temperature, constant pressure or constant flow liquid into the saturated area at the bottom of the flushing tank through the liquid inlet 11; turn on the hot air blower, and send the constant temperature gas into the drying area at the top of the flushing tank through the air inlet 3.

[0079] Step six, after the gas and liquid rates in the flushing tank are stable, control the linkage rod 19 to lift the baffle 17 to the top of the rock sample at a rated rate, and then lower it at the same rate.

[0080] Step 7: When the baffle returns to the bottom of the rock sample, drain the residual liquid in the flushing tank, turn on the hot air blower 1 and set the temperature to 95°C, dry the sample for 24 hours, and repeat step 3 to test the rock damage dynamic elastic modulus E. n According to the lossless dynamic elastic modulus E0 and the damaged dynamic elastic modulus E n The damage variable D can be defined as follows:

[0081]

[0082] This enables real-time dynamic monitoring of the degree of rock damage.

[0083] Step eight, repeat steps five to seven to obtain the damage characteristics of the rock sample under different cycle numbers, thereby revealing the degradation law of the rock sample.

[0084] In a specific embodiment, the parameters are set as follows: axial pressure = 5 MPa, water flow rate = 1 m / s, water temperature = 40° C., air temperature = 60° C., and number of cycles = 3 times.

[0085] Cut two specifications The cylindrical sandstone specimen was placed in an oven at 95°C for 24 hours. Then the rock sample was placed in a core holder and installed in a flushing tank. A constant axial pressure of 5 MPa was applied by a servo hydraulic pump. The propagation rates of P and S waves in the rock sample were measured using an ultrasonic probe, and the lossless dynamic elastic modulus E0 was calculated.

[0086] Operate the linkage rod to adjust the baffle to the bottom of the rock sample, then turn on the constant pressure and constant flow water pump to send 40°C, 1m / s water flow into the lower part of the flushing tank, and turn on the hot air blower to send 60°C gas into the upper part of the flushing tank. After the gas and liquid are stable, operate the linkage rod to raise the baffle to the top of the rock sample at a frequency of 1cm per hour, and then lower it at the same rate. After the baffle returns to the bottom, drain the residual liquid in the flushing tank, turn on the hot air blower and set the temperature to 95°C, dry the sample for 24 hours, and then measure the damage dynamic elastic modulus E1 of the rock sample after the first cycle through the acoustic system.

[0087] Repeat the above cycle and measure the damage dynamic elastic modulus E2 and E3 after the second and third cycles. The dynamic change law of the damage variable D with the increase of the number of cycles can be obtained, thus revealing the rock mass degradation mechanism under the condition of dynamic water level change.

[0088] By changing different environmental conditions (water level change rate, temperature change, water level change, axial pressure, water flow rate), we can also obtain more detailed laws of the influence of different factors on rock degradation.

[0089] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions described in the above embodiments can still be modified, or some or all of the technical features can be replaced by equivalents. These modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and specification of the present invention.

Claims

1. A rock degradation test system simulating dynamic changes in water levels, characterized in that: It includes single-axis hydraulic servo control subsystem, baffle lifting subsystem, water flow control subsystem, drying subsystem, temperature control subsystem and acoustic subsystem; The single-axis hydraulic servo control subsystem includes a servo hydraulic pump and a core holder, wherein the core holder is used to hold a rock sample, the core holder is partially embedded in a flushing water tank, the rock sample is located in the flushing water tank, and the servo hydraulic pump is connected to the core holder to apply pressure to the rock sample; The water barrier lifting subsystem includes a water barrier and a lifting assembly; wherein the water barrier is arranged in the flushing water tank, dividing the flushing water tank into a saturated area and a dry area, and the lifting assembly is connected to the water barrier to drive the water barrier to move up and down in the flushing water tank; The water flow control subsystem includes a circulating water storage tank, a constant pressure and constant flow water pump, a third check valve and a flow meter, and a fourth check valve; the circulating water storage tank is connected to the flushing water tank through a first pipe and a second pipe, the first pipe is provided with a constant pressure and constant flow water pump, a third check valve and a flow meter, and the second pipe is provided with the fourth check valve; The drying subsystem is used to dry the rock sample; The temperature control subsystem is used to regulate the temperature in the flushing tank; The acoustic subsystem measures the dynamic elastic modulus of the rock mass by emitting ultrasonic pulses and receiving reflected P and S waves, thereby achieving real-time dynamic characterization of the degree of damage during rock degradation.

2. The rock mass degradation test system for simulating dynamic changes in water level according to claim 1 is characterized in that: The core clamp comprises a hydraulic cylinder, a guide rail, a loading column and a pressure plate; the servo hydraulic pump is connected to the hydraulic cylinder, the hydraulic cylinder is connected to the loading column, the loading column is connected to the pressure plate, and the flushing water tank is installed on the guide rail.

3. The rock degradation test system for simulating dynamic changes in water level according to claim 1 is characterized in that: The lifting assembly includes a screw, a nut, a connecting rod and a silicone sealing strip; the baffle, screw and nut are each provided in two numbers, the connecting rod is connected to the two screws through a gear structure so that they rotate synchronously, the nut is assembled on the screw, and when the screw rotates, the meshing action of the thread and the nut pushes the screw up and down, thereby driving the baffle to move in a vertical direction, realizing the simulation of the dynamic change of the water level, and a silicone sealing strip is respectively installed at the contact position between the screw and the flushing trough and the contact position between the baffle and the flushing trough.

4. The rock degradation test system for simulating dynamic changes in water level according to claim 1, characterized in that: The drying subsystem includes a hot air blower and a waste liquid collector. The hot air blower is connected to an air inlet through a pipeline to send constant temperature cross-flow gas through the air inlet into a flushing water tank to heat or dry the rock sample. After the gas is fully in contact with the rock sample, it enters the waste liquid collector through an exhaust port and a pipeline. The pipeline connecting the hot air blower and the waste liquid collector is respectively equipped with a first check valve and a second check valve.

5. The rock degradation test system for simulating dynamic changes in water level according to claim 1 is characterized in that: The temperature control subsystem includes a temperature control element and a thermometer. The thermometer is arranged in the flushing water tank and is electrically connected to the temperature control element.

6. The rock degradation test system for simulating dynamic changes in water level according to claim 1, characterized in that: The acoustic subsystem includes a first ultrasonic probe, a second ultrasonic probe and a data acquisition and processing system; wherein the first ultrasonic probe and the second ultrasonic probe are arranged at two ends of the rock sample, and the first ultrasonic probe and the second ultrasonic probe are both connected to the data acquisition and processing system, and the data acquisition and processing system is used to control the first ultrasonic probe and the second ultrasonic probe to transmit ultrasonic pulses and receive reflected P and S waves to measure the dynamic elastic modulus of the rock mass, thereby realizing real-time dynamic characterization of the degree of damage during rock degradation.

7. A rock degradation test method simulating dynamic changes in water level, based on the rock degradation test system simulating dynamic changes in water level according to any one of claims 1 to 6, characterized in that: The method comprises: Step 1: Turn on the temperature control element in advance to heat the liquid in the circulating water storage tank to the rated temperature, install the completely dried rock sample in the core holder, and place the core holder in the flushing water tank; Step 2, start the servo hydraulic pump to apply a set axial pressure to the rock sample; Step 3, turning on the first ultrasonic probe and the second ultrasonic probe, transmitting a pulse signal and receiving the reflected P and S waves, and obtaining the propagation speed of the P and S waves in the rock mass by recording the propagation time, thereby obtaining the lossless dynamic elastic modulus of the rock; Step 4, rotate the linkage rod, adjust the position of the baffle plate through the screw rod, and lower the baffle plate to the bottom of the rock sample; Step 5, turn on the constant pressure and constant flow water pump to deliver the liquid with constant temperature, constant pressure and / or constant flow into the saturated area at the bottom of the flushing water tank through the liquid inlet; turn on the hot air blower to deliver the constant temperature gas into the drying area at the top of the flushing water tank through the air inlet; Step 6: After the gas and liquid rates in the flushing tank are stable, control the linkage rod to raise the baffle to the top of the rock sample at a rated rate, and then lower it at the same rated rate; Step 7: When the baffle returns to the bottom of the rock sample, drain the residual liquid in the flushing tank, turn on the hot air blower and set the drying temperature, dry the sample for 24 hours, and repeat step 3 to test the rock damage dynamic elastic modulus E. n ; Step 8, repeat steps 5 to 7 to obtain the damage characteristics of the rock sample under different cycle numbers, thereby revealing the degradation law of the rock sample.

8. The rock mass degradation test method for simulating dynamic changes in water level according to claim 7, characterized in that: In step 3 and step 7, the dynamic elastic modulus is obtained by the following formula: In the formula, E i is the dynamic elastic modulus, where i = 0 or n, n>0, representing the i-th water level dynamic cycle, when i = 0, E0 is the lossless elastic modulus, when i = n, E n is the damage elastic modulus under the nth water level dynamic cycle, ρ is the density of the rock sample, v pi 、v si are the propagation rates of P and S waves in rocks under the i-th water level dynamic cycle.

9. The rock mass degradation test method for simulating dynamic changes in water level according to claim 7, characterized in that: According to the lossless dynamic elastic modulus E0 and the damaged dynamic elastic modulus E n Determine the damage variable as shown in the following formula: Where D is the damage variable.

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