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

Abstract

The application belongs to the technical field of geotechnical test, and particularly discloses a rock mass degradation test system for simulating dynamic water level change and a test method, the system comprising a uniaxial hydraulic servo control subsystem, a waterproof plate lifting subsystem, a water flow control subsystem, a drying subsystem, a temperature control subsystem and an acoustic subsystem; the uniaxial hydraulic servo control subsystem comprises a servo hydraulic pump and a core holder; the waterproof plate lifting subsystem comprises a waterproof plate and a lifting assembly; the water flow control subsystem comprises a circulating water storage tank, a constant pressure and flow water pump, a third check valve, a flowmeter and a fourth check valve; the acoustic subsystem measures the dynamic elastic modulus of the rock mass by emitting ultrasonic pulses and receiving reflected P and S waves, so as to realize real-time dynamic characterization of the damage degree in the rock degradation process. The application can simulate the rock degradation scene under complex environmental conditions, especially under dynamic water level change conditions, and realize simulation of the damage inside the rock mass under the in-situ stress state.

Description

Technical Field

[0001] This invention relates to the field of testing technology related to rock mass deterioration, and in particular to a rock mass deterioration test system and test method that simulates dynamic changes in water level. Background Technology

[0002] Due to the periodic rise and fall of the water level in the Three Gorges Reservoir area between 145 and 175 meters, a drawdown zone with a vertical drop of 30 meters has been formed. The water level and environmental conditions (stress, temperature, water erosion, etc.) of the rock mass within the drawdown zone exhibit periodic changes, which leads to the rapid deterioration of the bank slope rock mass and further induces numerous geological disasters.

[0003] The deterioration process of rock masses is characterized by a complex environment. Dynamic changes in water level, water erosion, pressure from overlying rock masses, and the dry-hot-cold-wet cycle caused by temperature changes are the main causes of deterioration. Given these multiple factors, in-depth research on the deterioration process of rock masses under 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 flow guiding system, and a loading system. It can simulate the effects of complex dynamic water conditions and stress conditions on rock masses.

[0005] Chinese patent application CN114034629A discloses a system and method for monitoring rock mass damage under chemical corrosion conditions through wet-dry cycles. The device includes a wet-dry cycle test chamber, a chemical solution preparation container, a drying heat source supply box, and a host computer equipped with a damage calculation program. It can monitor rock mass damage during wet-dry cycles.

[0006] Chinese patent application CN111948241A discloses an experimental apparatus and method for simulating the degradation process of rock masses in drawdown zones. The apparatus includes an experimental chamber, 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 rock mechanical properties of rock masses in drawdown zones under different water levels, pressures, and 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. This device can adjust and control the water pressure, temperature, axial pressure, and saturation time during the saturation process, thereby simulating the behavior of rock masses under different environments.

[0008] The existing technology has the following drawbacks:

[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 changes (dynamic rise and fall of water level, water flow scouring, water pressure).

[0010] ② There is a lack of equipment and methods for in-situ testing of the degree of damage during rock deterioration. Existing testing methods require removing the rock for testing, which inevitably changes the degree of internal damage and cannot simulate the damage inside the rock under in-situ stress. Summary of the Invention

[0011] In view of the shortcomings of the prior art, the purpose of this invention is to provide a rock mass deterioration test system and test method for simulating dynamic changes in water level, so as to simulate the rock deterioration scenario 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] To achieve the above objectives, the present invention adopts the following technical solution:

[0013] In a first aspect, the present invention provides a rock mass deterioration test system for simulating dynamic changes in water level, including a single-axis hydraulic servo control subsystem, a water 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. The core holder is used to hold the rock sample. The core holder is partially embedded in the flushing water tank. The rock sample is located in the flushing water tank. The servo hydraulic pump is connected to the core holder and is used to apply pressure to the rock sample.

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

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

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

[0020] Furthermore, the core holder 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 lead screw, a nut, a connecting rod, and a silicone sealing strip; the water baffle, lead screw, and nut are all provided in pairs. The connecting rod is connected to the two lead screws through a gear structure, so that they rotate synchronously. The nut is mounted on the lead screw. When the lead screw rotates, the meshing action of the thread and the nut pushes the lead screw to move up and down, thereby driving the water baffle to move in the vertical direction, realizing the simulation of dynamic changes in water level. A silicone sealing strip is installed at the contact position between the lead screw and the flushing water tank, and at the contact position between the water baffle and the flushing water tank.

[0022] Furthermore, 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 pipe to send constant-temperature cross-flow gas into the flushing water tank to heat or dry the rock sample. After the gas comes into full contact with the rock sample, it enters the waste liquid collector through an exhaust port and a pipe. A first check valve and a second check valve are respectively installed on the pipes connecting the hot air blower and the waste liquid collector.

[0023] Furthermore, the temperature control subsystem includes a temperature control element and a thermometer, the thermometer being disposed in the flushing water tank and 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 and second ultrasonic probes are disposed at both ends of the rock sample, and both the first and second ultrasonic probes are connected to the data acquisition and processing system. The data acquisition and processing system is used to control the first and second ultrasonic probes to emit ultrasonic pulses and receive the 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 deterioration.

[0025] Secondly, the present invention provides a rock mass deterioration test method simulating dynamic changes in water level, based on the rock mass deterioration test system simulating dynamic changes in water level described in the first aspect, the method comprising:

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

[0027] Step 2: Turn on the servo hydraulic pump to apply the set axial pressure to the rock sample;

[0028] Step 3: Turn on the first and second ultrasonic probes, emit pulse signals and receive the reflected P and S waves. By recording the propagation time, the propagation speed of P and S waves in the rock mass is obtained, thereby obtaining the non-destructive dynamic elastic modulus of the rock.

[0029] Step 4: Rotate the connecting rod and adjust the position of the water-blocking plate through the screw to lower the water-blocking plate to the bottom of the rock sample;

[0030] Step 5: Turn on the constant pressure and constant flow water pump to send the constant temperature, constant pressure and / or constant flow liquid into the saturation zone at the bottom of the flushing tank through the liquid inlet; turn on the hot air blower to send the constant temperature gas into the drying zone at the top of the flushing tank through the air inlet.

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

[0032] Step 7: Once the water-separating plate has returned to the bottom of the rock sample, drain the remaining liquid from 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 dynamic elastic modulus E of the rock under damage. n ;

[0033] Step 8: Repeat steps 5 to 7 to obtain the damage characteristics of rock samples under different cycles, thereby revealing the deterioration law of the rock samples.

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

[0035]

[0036] In the formula, E i Let E0 be the dynamic elastic modulus, where i = 0 or n, n > 0, representing the i-th dynamic water level cycle. When i = 0, E0 is the lossless elastic modulus; when i = n, E... n Let ρ be the damage elastic modulus under the nth water level dynamic cycle, ρ be the density of the rock sample, and v be the elastic modulus of the rock sample. pi v si denoted as P and S, respectively, represent the propagation rates of P and S waves in the rock during the i-th water level dynamic cycle.

[0037] Furthermore, based on the undamaged dynamic elastic modulus E0 and the damaged dynamic elastic modulus E... nThe damage variable is determined as shown in the following formula:

[0038]

[0039] In the formula, D is the damage variable.

[0040] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0041] 1. It can simulate the effects of environmental stress, temperature, water flow and water level changes on the rock degradation process.

[0042] 2. In-situ non-destructive measurement of rock sample damage variables can be achieved using an ultrasonic probe.

[0043] 3. By separating the saturation system and the drying system through the lifting baffle, the actual environment can be better simulated, and the entire process of water level change can be simulated. Attached Figure Description

[0044] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0045] Figure 1 This is a schematic diagram of the overall structure of a rock mass deterioration test system for simulating dynamic changes in water level, provided in an embodiment of the present invention.

[0046] Figure 2 This is a schematic diagram of a core holder in a rock mass deterioration test system that simulates dynamic changes in water level, provided as an embodiment of the present invention.

[0047] Figure 3 This is a schematic diagram of the structure of a water-proof plate in a rock mass deterioration test system that simulates dynamic changes in water level, provided in an embodiment of the present invention.

[0048] Figure 4 A flowchart of a rock mass deterioration test method for simulating dynamic changes in water level, provided as an embodiment of the present invention.

[0049] Explanation of reference numerals in the attached figures:

[0050] 1-Hot air blower, 2-First check valve, 3-Air inlet, 4-Exhaust outlet, 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-Connecting rod, 20-Servo hydraulic pump, 21-Axial pressure gauge, 22-Hydraulic cylinder, 23-Pressure 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 Implementation

[0051] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, unless otherwise specified, the following embodiments and features described therein can be combined with each other.

[0052] In the description of this invention, unless otherwise stated, "a plurality of" means two or more; the terms "upper," "lower," "left," "right," "inner," "outer," "front end," "rear end," "head," "tail," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying their relative importance.

[0053] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

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

[0055] Example 1:

[0056] This invention provides a rock mass deterioration test system for simulating dynamic changes in water level. Please refer to [link / reference]. Figures 1 to 3 As shown, the rock mass deterioration test system simulating dynamic water level changes includes a single-axis hydraulic servo control subsystem, a baffle plate 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 explained 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 holder 2. The core holder 2 is used to hold the rock sample 25. The core holder 2 is partially embedded in the 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 holder 2 and is used to apply pressure to the rock sample 20.

[0059] Specifically, such as Figure 2 As shown, the core clamp 2 includes a hydraulic cylinder 22, a guide rail 30, a loading column 31, and a pressure plate 23; a 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 a flushing water 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 axial pressure of 0-200MPa, and the oil volume can be adjusted by the servo valve to stabilize the pressure at the target value, thereby simulating the stress environment of the rock mass. The components of the core holder 2, including the hydraulic cylinder 22, guide rail 30, loading column 31 and pressure plate 23, can all be embedded in the flushing water tank (28), which is the main place where water-rock interaction occurs. The servo hydraulic pump (20) delivers fluorinated oil into the hydraulic cylinder (22) through the oil inlet pipe. The hydraulic cylinder transmits the pressure to the loading column (31), and then transmits it to the pressure plate (23) to be applied to the rock mass (25). The axial pressure gauge (21) can observe the change of axial pressure. The pressure plate 23 includes upper and lower pressure plates, both of which are detachable for easy installation of rock samples.

[0061] The baffle plate lifting subsystem includes a baffle plate 17 and a lifting assembly; wherein, the baffle plate 17 is disposed in the flushing water tank 28, dividing the flushing water tank 28 into a saturated zone and a dry zone, and the lifting assembly is connected to the baffle plate 17 to drive the baffle plate 17 to move up and down in the flushing water tank 28.

[0062] Specifically, the lifting assembly includes a lead screw 18, a nut 29, a connecting rod 19, and a silicone sealing strip 32. Two lead screws 18 and two nuts 29 are provided. The connecting rod 19 is connected to the two lead screws 18 via a gear structure, allowing them to rotate synchronously. Nuts are mounted on the lead screws 18. When the lead screw 18 rotates, the meshing action of the thread and the nut 29 pushes the lead screw up and down, thereby driving the water baffle 17 to move vertically, simulating dynamic changes in water level. A silicone sealing strip 32 is installed at the contact points between the lead screw 18 and the flushing water tank 28, and between the water baffle 17 and the flushing water tank 28, respectively, to ensure no leakage occurs.

[0063] The water flow control subsystem includes a circulating water 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 tank 15 is connected to a flushing water tank 28 via a first pipe and a second pipe. The first pipe is equipped with the constant pressure and constant flow water pump 7, the third check valve 10, and the flow meter 8, while the second pipe is equipped with the fourth check valve 14. The constant pressure and constant flow water pump 7 pumps liquid at a constant flow rate into the flushing water tank 28 through the inlet 11 connected to the flushing water tank 28. 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 in real time. The third check valve 10 and the fourth check valve 14, installed near the inlet and outlet, are used for water monitoring and switching.

[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 an air inlet 3 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 25. After the gas comes into full contact with the rock sample, it enters the waste liquid collector through an exhaust port 4 and a pipe. A first check valve and a second check valve 5 are respectively equipped on the pipe connecting the hot air blower 1 and the waste liquid collector 6.

[0066] The temperature control subsystem is used to regulate the temperature inside 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 within the flushing water tank 28 and 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 the temperature change is monitored in real time by the thermometer 9 embedded within the system. Furthermore, the flushing water tank 28 may be wrapped with insulation material to ensure uniform water temperature within it.

[0068] The acoustic subsystem measures the dynamic elastic modulus of the rock mass by emitting ultrasonic pulses and receiving the reflected P and S waves, thereby enabling 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 disposed at both ends of the rock sample 25, and both the first ultrasonic probe 24 and the second ultrasonic probe 26 are connected to the data acquisition and processing system 27. 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 the 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 the rock deterioration process.

[0070] Example 2:

[0071] This invention provides a method for simulating dynamic water level changes in rock mass degradation testing. This method is based on the rock mass degradation testing apparatus for simulating dynamic water level changes as described in Example 1. Please refer to [link to example 1]. Figure 4 As shown, this test method for simulating dynamic changes in water level and rock mass deterioration is performed by the following steps:

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

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

[0074] Step 3: Turn on the first ultrasonic probe 24 and the second ultrasonic probe 26, emit pulse signals and receive the reflected P and S waves. Record the propagation time to obtain the propagation speed of the P and S waves in the rock mass, thereby obtaining the non-destructive dynamic elastic modulus E0 of the rock. Dynamic elastic modulus E0 i The dynamic elastic modulus E is mainly obtained through the following formula. i With respect to the propagation speeds v of P and S waves pi v si There exists a corresponding functional relationship between them:

[0075]

[0076] In the formula, E i Let E0 be the dynamic elastic modulus, where i = 0 or n, n > 0, representing the i-th dynamic water level cycle. When i = 0, E0 is the lossless elastic modulus; when i = n, E... n Let ρ be the damage elastic modulus under the nth water level dynamic cycle, ρ be the density of the rock sample, and v be the elastic modulus of the rock sample. pi v si denoted as P and S, respectively, represent the propagation rates of P and S waves in the rock during the i-th water level dynamic cycle.

[0077] Step 4: Rotate the connecting rod 19 and adjust the position of the water-blocking plate 17 through the screw 18 to lower the water-blocking plate to the bottom of the rock sample.

[0078] Step 5: Turn on the constant pressure and constant flow water pump 7 to send the constant temperature, constant pressure or constant flow liquid into the lower saturation zone of the flushing water tank through the liquid inlet 11; turn on the hot air blower to send the constant temperature gas into the upper drying zone of the flushing water tank through the air inlet 3.

[0079] Step six: After the gas and liquid rates in the flushing tank stabilize, control the linkage rod 19 to raise the water-blocking plate 17 to the top of the rock sample at the rated rate, and then lower it at the same rate.

[0080] Step 7: Once the water-separating plate has returned to the bottom of the rock sample, drain the remaining liquid from the flushing tank, turn on the hot air blower 1 and set the temperature to 95℃, and dry the sample for 24 hours. Repeat Step 3 to test the dynamic elastic modulus E of the rock under damage. n Based on the undamaged dynamic elastic modulus E0 and the damaged dynamic elastic modulus E n The damage variable D can be defined as shown in the following formula:

[0081]

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

[0083] Step 8: Repeat steps 5 to 7 to obtain the damage characteristics of rock samples under different cycles, thereby revealing the deterioration law of the rock samples.

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

[0085] Cut two specifications Cylindrical sandstone specimens were dried in an oven at 95°C for 24 hours. The rock samples were then loaded into a core holder and placed in a flushing tank. A constant axial pressure of 5 MPa was applied using a servo hydraulic pump. The propagation rates of P-waves and S-waves in the rock samples were measured using an ultrasonic probe, and the non-destructive dynamic elastic modulus E0 was calculated.

[0086] Operate the linkage rod to adjust the baffle plate to the bottom of the rock sample. Then, turn on the constant pressure and constant flow water pump to send water at 40℃ and 1m / s into the lower part of the flushing tank, and turn on the hot air blower to send gas at 60℃ into the upper part of the flushing tank. After the gas and liquid have stabilized, operate the linkage rod to raise the baffle plate 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 plate returns to the bottom, drain the residual liquid in the flushing tank, turn on the hot air blower and set the temperature to 95℃ to dry the sample for 24 hours. Then, measure the dynamic elastic modulus of damage E1 of the rock sample after the first cycle using the acoustic system.

[0087] Repeat the above cycle and measure the dynamic elastic modulus of damage, E2 and E3, after the second and third cycles. This allows us to obtain the dynamic change law of the damage variable D with the increase of the number of cycles, thus revealing the mechanism of rock mass deterioration under dynamic water level changes.

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

[0089] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention.

Claims

1. A rock mass deterioration test method simulating dynamic changes in water level, based on a rock mass deterioration test system simulating dynamic changes in water level, characterized in that, It includes a single-axis hydraulic servo control subsystem, a baffle plate lifting subsystem, a water flow control subsystem, a drying subsystem, a temperature control subsystem, and an acoustic subsystem; The single-axis hydraulic servo control subsystem includes a servo hydraulic pump and a core holder. The core holder is used to hold the rock sample. The core holder is partially embedded in the flushing water tank. The rock sample is located in the flushing water tank. The servo hydraulic pump is connected to the core holder and is used to apply pressure to the rock sample. The baffle plate lifting subsystem includes a baffle plate and a lifting assembly; wherein, the baffle plate is disposed in the flushing water tank, dividing the flushing water tank into a saturated zone and a dry zone, and the lifting assembly is connected to the baffle plate to drive the baffle plate to move up and down in the flushing water tank; The water flow control subsystem includes a circulating water tank, a constant pressure and constant flow water pump, a third check valve, a flow meter, and a fourth check valve; the circulating water tank is connected to the flushing water tank through a first pipe and a second pipe, the first pipe is equipped with a constant pressure and constant flow water pump, a third check valve, and a flow meter, and the second pipe is equipped 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 inside the flushing water tank; The acoustic subsystem measures the dynamic elastic modulus of the rock mass by emitting ultrasonic pulses and receiving the reflected P and S waves, thereby achieving real-time dynamic characterization of the degree of damage during the rock deterioration process. The method includes: Step 1: Turn on the temperature control element in advance to heat the liquid in the circulating water tank to the rated temperature, install the completely dried rock sample into the core holder, and place the core holder in the flushing water tank. Step 2: Turn on the servo hydraulic pump to apply the set axial pressure to the rock sample; Step 3: Turn on the first and second ultrasonic probes, emit pulse signals and receive the reflected P and S waves. By recording the propagation time, the propagation speed of P and S waves in the rock mass is obtained, thereby obtaining the non-destructive dynamic elastic modulus of the rock. Step 4: Rotate the connecting rod and adjust the position of the water-blocking plate through the screw to lower the water-blocking plate to the bottom of the rock sample; Step 5: Turn on the constant pressure and constant flow water pump to send the constant temperature, constant pressure and / or constant flow liquid into the saturation zone at the bottom of the flushing tank through the liquid inlet; turn on the hot air blower to send the constant temperature gas into the drying zone at the top of the flushing tank through the air inlet. Step 6: After the gas and liquid rates in the flushing tank stabilize, control the linkage rod to raise the baffle plate to the top of the rock sample at the rated rate, and then lower it at the same rated rate. Step 7: Once the water-separating plate has returned to the bottom of the rock sample, drain the remaining liquid from 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 dynamic elastic modulus E of the rock under damage. n ; Step 8: Repeat steps 5 to 7 to obtain the damage characteristics of rock samples under different cycles, thereby revealing the deterioration law of the rock samples.

2. The rock mass deterioration test method simulating dynamic water level changes according to claim 1, characterized in that, The core holder 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.

3. The rock mass deterioration test method simulating dynamic water level changes according to claim 1, characterized in that, The lifting assembly includes a lead screw, a nut, a connecting rod, and a silicone sealing strip. Two leads, a water baffle, and two nuts are provided. The connecting rod is connected to the two lead screws via a gear structure, allowing them to rotate synchronously. The nuts are mounted on the lead screws. When the lead screw rotates, the meshing action of the thread and the nut pushes the lead screw up and down, thereby causing the water baffle to move vertically, simulating dynamic changes in water level. A silicone sealing strip is installed at each contact point between the lead screw and the flushing trough, and at each contact point between the water baffle and the flushing trough.

4. The rock mass deterioration test method simulating dynamic water level changes 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 pipe to send constant-temperature, cross-flowing gas into the flushing water tank to heat or dry the rock sample. After the gas comes into full contact with the rock sample, it enters the waste liquid collector through an exhaust port and a pipe. A first check valve and a second check valve are respectively installed on the pipes connecting the hot air blower and the waste liquid collector.

5. The rock mass deterioration test method simulating dynamic water level changes according to claim 1, characterized in that, The temperature control subsystem includes a temperature control element and a thermometer. The thermometer is installed in the flushing water tank and is electrically connected to the temperature control element.

6. The rock mass deterioration test method simulating dynamic water level changes 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. The first and second ultrasonic probes are located at both ends of the rock sample, and both are connected to the data acquisition and processing system. The data acquisition and processing system controls the first and second ultrasonic probes to emit ultrasonic pulses and receive reflected P and S waves to measure the dynamic elastic modulus of the rock mass, thereby achieving real-time dynamic characterization of the degree of damage during rock deterioration.

7. The rock mass deterioration test method simulating dynamic water level changes according to claim 1, characterized in that, In steps 3 and 7, the dynamic elastic modulus is obtained using the following formula: In the formula, E i Let E0 be the dynamic elastic modulus, where i = 0 or n, n > 0, representing the i-th dynamic water level cycle. When i = 0, E0 is the lossless elastic modulus; when i = n, E... n Let ρ be the damage elastic modulus under the nth water level dynamic cycle, ρ be the density of the rock sample, and v be the elastic modulus of the rock sample. pi v si denoted as P and S, respectively, represent the propagation rates of P and S waves in the rock during the i-th water level dynamic cycle.

8. The rock mass deterioration test method simulating dynamic water level changes according to claim 1, characterized in that, Based on the undamaged dynamic elastic modulus E0 and the damaged dynamic elastic modulus E n The damage variable is determined as shown in the following formula: In the formula, D is the damage variable.

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