A water-heat-force coupling test system and method for open-pit slope rock-soil mass degradation evaluation

Abstract

The present application relates to a kind of water-thermal-mechanical coupling test system and method for open-pit mine slope rock-soil mass degradation evaluation, belong to geotechnical engineering test field.System includes impact loading machine, triaxial pressure chamber, transverse static presser, freeze-thaw experiment box, direct shear coupling seepage pressurizing device and control system, wherein, impact loading machine middle part is provided with triaxial pressure chamber, triaxial pressure chamber both sides are symmetrically provided with transverse static presser, triaxial pressure chamber is connected with freeze-thaw experiment box and direct shear coupling seepage pressurizing device, impact loading machine, transverse static presser, freeze-thaw experiment box and direct shear coupling seepage pressurizing device are all connected with control system.The present application can simulate the coupling effect environment of seepage, freeze-thaw cycle, static load and blasting dynamic load disturbance of open-pit mine slope rock-soil mass simultaneously, and real-time, positioning evaluation is carried out to rock-soil mass degradation process based on acoustic emission monitoring technology.

Description

Technical Field

[0001] This invention relates to a water-thermal-mechanical coupling test system and method for assessing the deterioration of soil and rock masses on open-pit mine slopes, belonging to the field of geotechnical engineering test technology. Background Technology

[0002] With the increasing demand for mineral resources in my country, the scale and depth of open-pit mining are constantly expanding, and the environment of mine slopes is becoming increasingly complex. The soil and rock masses are constantly undergoing dynamic deterioration under the coupling of multiple water-thermal-mechanical fields. They bear the static load of the rock strata's own weight and mining disturbances, and are frequently subjected to the instantaneous impact of blasting vibrations and mechanical excavation. Simultaneously, they are subject to continuous erosion from seasonal freeze-thaw cycles and multi-directional groundwater seepage, making slope stability issues increasingly prominent. Slope instability not only directly interrupts mining progress but also easily triggers major safety accidents such as landslides and collapses, as well as secondary environmental disasters, causing huge economic losses and ecological damage. Accurately assessing the mechanical properties and deterioration patterns of the soil and rock masses is the core data support and key technological prerequisite for predicting open-pit mine slope instability risks, scientifically designing slope engineering and reinforcement schemes, ensuring safe and continuous mining, optimizing mining processes and reducing operating costs, and achieving intelligent slope management.

[0003] Existing multi-field coupling testing machines are important equipment for simulating complex environments in soil and rock masses. Their core advantage lies in their ability to initially integrate stress, seepage, and temperature fields, enabling the testing of the mechanical response of soil and rock masses under coupled conditions. Furthermore, they offer high precision in multi-physics field coordinated control and broad experimental data coverage, making them suitable for studying multi-field coupling effects in fields such as deep rock engineering and geothermal development. However, these devices have significant drawbacks: Firstly, the pressure chamber structure typically employs a single-cavity design. While this allows for the application of multiple fields, mutual interference exists between the various physical fields, making independent and precise control of each field impossible and failing to simulate the complex environment of zonal interactions in actual engineering projects. Secondly, the seepage path settings are still primarily unidirectional or simple radial, failing to reproduce the multidirectional seepage characteristics of soil and rock masses in three-dimensional space.

[0004] Moreover, existing open-pit mine slope soil and rock degradation assessment methods are typically based on conventional laboratory mechanical tests or in-situ field tests. Their core advantage lies in obtaining basic mechanical parameters (such as compressive strength and elastic modulus) and macroscopic deformation characteristics of the soil and rock, providing fundamental data support for slope stability analysis. However, these methods have significant shortcomings: assessment methods largely rely on macroscopic state comparisons before and after the test or periodic sampling tests, lacking the ability to dynamically monitor the microscopic damage evolution of the soil and rock during degradation, such as the initiation, propagation, and penetration of microcracks. They can only infer the degradation mechanism from the final failure morphology and cannot achieve real-time quantitative assessment of the degree of degradation and spatial location of damage. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a water-thermal-mechanical coupling test system and method for assessing the deterioration of soil and rock masses on open-pit mine slopes. This system can simultaneously simulate the coupled effects of seepage, freeze-thaw cycles, static loads, and dynamic blasting disturbances on open-pit mine slope soil and rock masses, and perform real-time, location-based assessment of the soil and rock mass deterioration process based on acoustic emission monitoring technology.

[0006] A water-thermal-mechanical coupled testing system for assessing the deterioration of soil and rock masses on open-pit mine slopes includes an impact loader, a triaxial pressure chamber, a transverse static pressurizer, a freeze-thaw test chamber, a direct shear coupled seepage pressurization device, and a control system, wherein: The impact loader has a triaxial pressure chamber in the middle, and transverse static presses are symmetrically arranged on both sides of the triaxial pressure chamber. A freeze-thaw test chamber and a direct shear coupled seepage pressurization device are connected to the outside of the triaxial pressure chamber. The impact loader, transverse static presses, freeze-thaw test chamber and direct shear coupled seepage pressurization device are all connected to a control system.

[0007] According to a preferred embodiment of the present invention, the impact loading machine includes a body, an axial pressure cylinder, a high-frequency electro-hydraulic servo impact actuator, an impact rod, a magnetostrictive displacement sensor, and a base. An axial pressure cylinder is located at the top of the body, and its piston is connected to the impact rod for outputting a stable axial load. A static pressure transmission path is formed between the piston, the impact rod, and the upper surface of the sample to simulate rock pressure and long-term creep effects. A high-frequency electro-hydraulic servo impact actuator is located at the top of the body, and this actuator, together with the impact rod, constitutes a dynamic loading module. Dynamic loading at different frequencies is achieved through servo valve control, simulating low-frequency vibrations in the far-field of blasting. The magnetostrictive displacement sensor is used to monitor the displacement signal of the impact rod in real time. A base is located at the bottom of the body.

[0008] According to a further preferred embodiment of the present invention, a triaxial pressure chamber is provided in the middle of the machine body, and a guide sleeve is provided on the machine body above the triaxial pressure chamber. An impact rod is fitted inside the guide sleeve. The guide sleeve is used to ensure the impact alignment accuracy. A drop hammer that can fall freely is provided at the end of the impact rod to realize the instantaneous impact load generated by superimposing instantaneous impact on the static preload to simulate near-zone blasting or mechanical impact. Hydraulic cylinders are symmetrically arranged on the machine body on both sides of the triaxial pressure chamber to provide power support.

[0009] According to a preferred embodiment of the present invention, the triaxial pressure chamber includes a support column and a double-layer shell. The double-layer shell is provided on the upper side of the support column. The inner layer of the double-layer shell is a pressure-bearing cavity, and the outer layer is a heat insulation layer. A temperature-controlled interlayer is provided between the inner and outer layers. A temperature-controlled inlet and a temperature-controlled outlet are provided on the outside of the temperature-controlled interlayer for introducing a temperature-controlled medium. A transverse static press is provided on both sides of the triaxial pressure chamber. The outer side of the double-layer shell is connected to a hydraulic cylinder and a transverse static press via a pressure plate (the hydraulic cylinder provides power support, and the transverse static press applies pressure). An impact rod is connected to the top of the double-layer shell via a pressure plate. The pressure plate ensures that the sample is subjected to balanced and stable force.

[0010] According to a further preferred embodiment of the present invention, a seepage distribution plate is provided at the top of the support column. The seepage distribution plate is a porous plate structure with holes of different diameters opened in different zones to form differentiated seepage. Each hole on the seepage distribution plate is connected to an independent seepage pipe. Each seepage pipe is equipped with a solenoid valve. Relying on the independent opening and closing and flow regulation functions of each solenoid valve, the on / off state and flow rate of the corresponding flow channel in each zone of the seepage distribution plate can be precisely controlled, thereby realizing independent control of multiple fluids and directional control of multi-directional seepage. The fluid circulation and transportation are completed in conjunction with the closed loop of the seepage fluid inlet and outlet.

[0011] According to a preferred embodiment of the present invention, a temperature sensor and an acoustic emission monitoring sensor are installed on the triaxial pressure chamber. Through the coordinated operation of the overall structure, the synchronous application of multi-field loads (water, heat, and force) and real-time acquisition and monitoring of multi-dimensional signals are achieved. The acoustic emission monitoring sensor is arranged in an array, with its detection end penetrating the insulation layer and contacting the surrounding environment of the sample. Through waveform time-difference positioning technology, the generation and development of microcracks inside the sample are located in three-dimensional space.

[0012] According to a preferred embodiment of the present invention, the freeze-thaw test chamber is connected to the temperature control inlet and temperature control outlet of the triaxial pressure chamber via pipelines. When the freeze-thaw test chamber starts refrigeration or heating operations, the temperature control medium circulates within the temperature control interlayer to form a uniform and stable freeze-thaw temperature field across the entire field.

[0013] According to a preferred embodiment of the present invention, the direct shear coupling percolation pressurization device includes a gas source, a gas booster pump, a constant pressure and constant speed pump, and a filter. The outlet of the gas source is connected to the inlet of the gas booster pump, the outlet of the gas booster pump is connected to the inlet of the constant pressure and constant speed pump, and the outlet of the constant pressure and constant speed pump is connected to the inlet of the percolation pipe at the bottom of the support column after passing through the filter. When the gas source supplies gas and each pump is started, the percolation medium enters along the inlet channel after being pressurized and filtered, and percolates evenly into the interior of the sample through the percolation distribution plate, forming a controllable percolation circulation path between the pores and cracks of the sample and the external pipeline.

[0014] According to a preferred embodiment of the present invention, both the impact loader and the transverse static press are equipped with pressure sensors, and the direct shear seepage pressurization device is equipped with a pressure flow sensor.

[0015] The test method for the water-thermal-mechanical coupling test system used for assessing the deterioration of rock and soil in open-pit mine slopes, as described above, includes the following steps: (1) Select the soil and rock mass of typical areas of open-pit mine slope, prepare standard specimens according to the preset size, pre-treat the specimens (drying, saturation or natural moisture content adjustment), put the prepared specimens into the pressure chamber of the triaxial pressure chamber, position them by the pressure plate to ensure that the specimens are placed in the center and closely attached to the upper and lower pressure surfaces, then seal the pressure chamber, connect the freeze-thaw test chamber to the temperature control inlet and temperature control outlet to complete the construction of the closed-loop temperature control circuit, connect the direct shear coupling seepage pressurization device through the seepage pipe interface, match the electromagnetic valve to realize seepage interruption control, connect the liquid inlet and liquid outlet simultaneously to ensure the seepage medium circulation path, arrange acoustic emission monitoring sensors and temperature sensors, and finally connect to the control system to complete the full system circuit network; (2) The test parameters are preset through the control system, and then the initial confining pressure and axial static load are applied to the specimen to simulate the in-situ stress state of the slope. The acoustic emission background signal and initial elastic wave velocity under low load are collected to establish the non-destructive state reference parameters (initial elastic modulus, initial seepage coefficient). (3) After the formal test is started, the transverse static press applies transverse stress to the specimen according to the preset pressure. The impact loader first applies axial static pressure through the axial press cylinder, and then outputs pulse impact load at the set frequency through the high-frequency electro-hydraulic servo impact actuator and the impact rod to simulate the low-frequency vibration in the far zone and the instantaneous impact in the near zone of the explosion. The freeze-thaw test chamber is started and the temperature control medium is delivered to the temperature control jacket of the pressure chamber. After the seepage medium is pressurized by the gas booster pump and filtered by the filter, it is delivered through the seepage pipe under the control of the solenoid valve and seeps into the interior of the specimen through the seepage distribution plate. During the test, the control system collects the impact load output by the impact loader, the transverse pressure output by the transverse static press, the temperature monitored by the temperature sensor, the seepage pressure flow rate and the acoustic emission signal (number of events, energy) collected by the acoustic emission monitoring sensor in real time, and performs signal filtering and analysis processing simultaneously. (4) The control system performs real-time calculations, using the degree of degradation D as the core evaluation index. The calculation formula is as follows:

[0016] Where E is the elastic modulus monitored in real time during the test, E0 is the initial elastic modulus, N is the number of real-time cumulative acoustic emission events, and N0 is the number of critical acoustic emission events (determined through indoor calibration tests, with a value range of 10). 4 ~10 6 ), α is a correction factor (related to the type of rock mass; for hard rock mass, α = 0.8-1.2; for soft rock mass, α = 1.2-1.5). Simultaneously, the rate of change of the seepage coefficient is used as an auxiliary criterion:

[0017] Where k is the real-time monitoring seepage coefficient, and k0 is the initial seepage coefficient; Finally, the degradation level is classified:

[0018] The criteria for classifying the degradation levels are as follows: Slight deterioration: When D < 0.3 and η > 0.5, the mechanical properties of the rock mass are slightly degraded, the internal microcracks are in the initial development stage, the seepage channels have not yet formed, the overall structure remains intact, and the slope is in a safe and stable state. Moderate deterioration: When 0.3≤D<0.7 and 0.5≤η<1.5, the mechanical properties of the rock mass decrease significantly, microcracks continue to expand and gradually penetrate, the seepage coefficient increases significantly, and the slope stability decreases significantly. It is necessary to intensify monitoring and carry out reinforcement measures. Critical failure: When D≥0.7 or η≥1.5, the mechanical properties of the rock mass are severely deteriorated, the crack network is basically connected, the seepage channel is fully formed, and the slope is on the verge of instability. (5) When the specimen enters the critical failure level, or reaches the preset number of test cycles and time, first turn off the pressurization function of the axial pressurizing cylinder, the high-frequency electro-hydraulic servo impact actuator and the transverse static pressurizer to unload the stress, then stop the temperature control of the freeze-thaw test chamber, turn off the direct shear coupling seepage pressurization device, cut off the seepage medium supply, and after the temperature in the pressure chamber drops to room temperature and the pressure is completely unloaded, take out the specimen, observe and record the specimen deterioration morphology (crack distribution, failure mode), organize the test data collected by the control system, and generate a test report containing multi-field parameter curves, deterioration index change curves and damage evolution cloud maps. If different parameters need to be tested, repeat steps (1) to (5).

[0019] 1. This invention integrates a triaxial pressure chamber, with an inner pressure-bearing cavity and an outer insulation layer. A temperature-controlled medium circulates within the temperature-controlled interlayer, enabling simultaneous application and physical isolation of mechanical loading and thermal cycling. This solves the technical bottleneck of mutual interference and asynchronous loading in traditional equipment. Furthermore, it sets up multiple independently controlled seepage channels, combined with a bottom seepage distribution plate and multi-directional outlets on the side walls, to construct a three-dimensional multi-directional seepage path simulation system. This system can set seepage pressure and gradient in different directions according to the actual engineering situation, realistically reproducing the multi-directional seepage characteristics of soil and rock in three-dimensional space.

[0020] 2. This invention introduces high-precision acoustic emission monitoring technology, deploys acoustic emission sensors to capture acoustic emission signals in real time during the initiation, propagation, and penetration of microcracks in soil and rock under the action of water-thermal-mechanical coupling. Combined with waveform time-difference positioning technology, it realizes three-dimensional spatial positioning of damage sources. At the same time, it integrates the attenuation of mechanical parameters and the changes in seepage characteristics to construct a multi-dimensional integrated deterioration assessment model of mechanics-acoustic emission-seepage. By quantifying the mathematical expression of the degree of deterioration D and the rate of change of seepage coefficient, it establishes a grading criterion to realize real-time quantitative assessment of the deterioration process of soil and rock and visualize the damage evolution. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of the present invention.

[0022] Figure 2 This is a cross-sectional structural diagram of the overall structure of the impact loader of the present invention.

[0023] Figure 3 This is a schematic diagram of the triaxial pressure chamber of the present invention.

[0024] Figure 4 This is a schematic diagram of the acoustic emission monitoring sensor arrangement according to the present invention.

[0025] Figure 5 This is a schematic diagram of the direct shear coupling seepage pressurization device of the present invention.

[0026] Figure 6 This is a schematic diagram of the seepage distribution plate structure of the present invention.

[0027] Figure 7 This is a schematic diagram of the method flow of the present invention.

[0028] Among them: 1-Impact loader; 2-Triaxial pressure chamber; 3-Transverse static pressurizer; 4-Freeze-thaw test chamber; 5-Direct shear coupling seepage pressurization device; 6-Control system; 101-Magnetostrictive displacement sensor; 102-High-frequency electro-hydraulic servo impact actuator; 103-Servo valve; 104-Piston; 105-Axial pressure cylinder; 106-Guide sleeve; 107-Falling hammer; 108-Impact rod; 109-Hydraulic cylinder; 110-Base; 201-Temperature control inlet; 202-Temperature control outlet; 203-Seepage pipe; 204-Solenoid valve; 205-Liquid inlet; 206-Liquid outlet; 207-Pressure plate; 208-Specimen; 209-Seepage distribution plate; 210-Temperature sensor; 211-Pressure chamber; 212-Insulation layer; 213-Acoustic emission monitoring sensor; 2091 - Large hole; 2092 - Small hole; 501 - Filter; 502 - Gas booster pump; 503 - Constant pressure and constant speed pump; 504 - Gas source. Detailed Implementation

[0029] The present invention will be further described below with reference to the embodiments and accompanying drawings, but is not limited thereto. Example

[0030] like Figure 1-7 As shown, this embodiment provides a water-thermal-mechanical coupled test system for assessing the deterioration of soil and rock masses on open-pit mine slopes, including an impact loader 1, a triaxial pressure chamber 2, a transverse static pressurizer 3, a freeze-thaw test chamber 4, a direct shear coupled seepage pressurization device 5, and a control system 6, wherein: The impact loader 1 has a triaxial pressure chamber 2 in the middle, and transverse static presses 3 are symmetrically arranged on both sides of the triaxial pressure chamber 2. The triaxial pressure chamber 2 is connected to a freeze-thaw test chamber 4 and a direct shear coupled seepage pressurization device 5. The impact loader 1, the transverse static presses 3, the freeze-thaw test chamber 4 and the direct shear coupled seepage pressurization device 5 are all connected to a control system 6.

[0031] The impact loader 1 includes a body, an axial pressure cylinder 105, a high-frequency electro-hydraulic servo impact actuator 102, an impact rod 108, a magnetostrictive displacement sensor 101, and a base 110. The axial pressure cylinder 105 is located at the top of the body. The piston 104 of the axial pressure cylinder is connected to the impact rod 108 for outputting a stable axial load. A static pressure transmission path is formed between the piston 104, the impact rod 108, and the upper end face of the specimen 208 to simulate rock pressure and long-term creep effect. The high-frequency electro-hydraulic servo impact actuator 102 is located at the top of the body. The high-frequency electro-hydraulic servo impact actuator 102, together with the impact rod 108, constitutes a dynamic loading module. The dynamic loading at different frequencies is controlled by the servo valve 103 to simulate low-frequency vibration in the far zone of blasting. The magnetostrictive displacement sensor 101 is used to monitor the displacement signal of the impact rod in real time. The base 110 is located at the bottom of the body.

[0032] A triaxial pressure chamber 2 is set in the middle of the machine body. A guide sleeve 106 is set on the machine body above the triaxial pressure chamber 2. An impact rod 108 is installed inside the guide sleeve 106. The guide sleeve 106 is used to ensure the impact centering accuracy. A drop hammer 107 that can fall freely is set at the end of the impact rod 108 to realize the instantaneous impact load generated by superimposing instantaneous impact on the static preload to simulate near-zone blasting or mechanical impact. Hydraulic cylinders 109 are symmetrically arranged on the machine body on both sides of the triaxial pressure chamber 2 to provide power support.

[0033] The triaxial pressure chamber 2 includes a support column and a double-layer shell. The double-layer shell is located on the upper side of the support column. The inner layer of the double-layer shell is a pressure-bearing cavity 211, and the outer layer is a heat insulation layer 212. A temperature control interlayer is located between the inner and outer layers. A temperature control inlet 201 and a temperature control outlet 202 are provided on the outside of the temperature control interlayer for introducing a temperature control medium. A transverse static press 3 is provided on both sides of the triaxial pressure chamber 2. The outer side of the double-layer shell is connected to the hydraulic cylinder 109 and the transverse static press (the hydraulic cylinder provides power support, and the transverse static press applies pressure) through the pressure plate 207. An impact rod 108 is connected to the top of the double-layer shell through the pressure plate. The pressure plate ensures that the sample is subjected to balanced and stable force.

[0034] A seepage distribution plate 209 is installed at the top of the support column. The seepage distribution plate 209 is a porous plate structure with holes of different diameters (large holes 2091, small holes 2092) in different zones to form differentiated seepage. Each hole on the seepage distribution plate 209 is connected to an independent seepage pipe 203. Each seepage pipe is equipped with a solenoid valve 204. Relying on the independent opening and closing and flow regulation functions of each solenoid valve, the on / off state and flow rate of the corresponding flow channel in each zone of the seepage distribution plate can be precisely controlled, thereby realizing independent control of multiple fluids and directional control of multi-directional seepage. It works in conjunction with the closed loop of the seepage fluid inlet and outlet to complete the fluid circulation and transportation.

[0035] Temperature sensor 210 and acoustic emission monitoring sensor 213 are installed on the triaxial pressure chamber 2. Through the coordinated operation of the overall structure, the synchronous application of multi-field loads of water, heat and force and real-time acquisition and monitoring of multi-dimensional signals are realized. The acoustic emission monitoring sensor is arranged in an array, with the detection end penetrating the insulation layer and contacting the surrounding environment of the sample. Through waveform time difference positioning technology, the generation and development of microcracks inside the sample are located in three-dimensional space.

[0036] The freeze-thaw test chamber 4 is connected to the temperature control inlet 201 and temperature control outlet 202 of the triaxial pressure chamber via pipelines. When the freeze-thaw test chamber starts refrigeration or heating, the temperature control medium circulates in the temperature control jacket to form a uniform and stable freeze-thaw temperature field throughout the entire field.

[0037] The direct shear coupling seepage pressurization device 5 includes a gas source 504, a gas booster pump 502, a constant pressure and constant speed pump 503, and a filter 501. The outlet of the gas source is connected to the inlet of the gas booster pump 502, and the outlet of the gas booster pump 502 is connected to the inlet of the constant pressure and constant speed pump 503. The outlet of the constant pressure and constant speed pump 503 is connected to the inlet of the seepage pipe 203 at the bottom of the support column after passing through the filter. When the gas source supplies gas and each pump starts, the seepage medium enters along the inlet channel after being pressurized and filtered, and evenly seeps into the interior of the sample through the seepage distribution plate, forming a controllable seepage circulation path between the sample pores, cracks and external pipelines.

[0038] Pressure sensors are installed in both the impact loader 1 and the transverse static press 3, and pressure and flow sensors are installed in the direct shear seepage pressurization device.

[0039] The test method for the water-thermal-mechanical coupling test system used for assessing the deterioration of rock and soil in open-pit mine slopes, as described above, includes the following steps: (1) Select the soil and rock mass of typical areas of open-pit mine slope, prepare standard specimens according to the preset size, pre-treat the specimens (drying, saturation or natural moisture content adjustment), put the prepared specimens into the pressure chamber of the triaxial pressure chamber, position them by the pressure plate to ensure that the specimens are placed in the center and closely attached to the upper and lower pressure surfaces, then seal the pressure chamber, connect the freeze-thaw test chamber to the temperature control inlet and temperature control outlet to complete the construction of the closed-loop temperature control circuit, connect the direct shear coupling seepage pressurization device through the seepage pipe interface, match the electromagnetic valve to realize seepage interruption control, connect the liquid inlet and liquid outlet simultaneously to ensure the seepage medium circulation path, arrange acoustic emission monitoring sensors and temperature sensors, and finally connect to the control system to complete the full system circuit network; (2) The test parameters are preset through the control system, and then the initial confining pressure and axial static load are applied to the specimen to simulate the in-situ stress state of the slope. The acoustic emission background signal and initial elastic wave velocity under low load are collected to establish the non-destructive state reference parameters (initial elastic modulus, initial seepage coefficient). (3) After the formal test is started, the transverse static press applies transverse stress to the specimen according to the preset pressure. The impact loader first applies axial static pressure through the axial press cylinder, and then outputs pulse impact load at the set frequency through the high-frequency electro-hydraulic servo impact actuator and the impact rod to simulate the low-frequency vibration in the far zone and the instantaneous impact in the near zone of the explosion. The freeze-thaw test chamber is started and the temperature control medium is delivered to the temperature control jacket of the pressure chamber. After the seepage medium is pressurized by the gas booster pump and filtered by the filter, it is delivered through the seepage pipe under the control of the solenoid valve and seeps into the interior of the specimen through the seepage distribution plate. During the test, the control system collects the impact load output by the impact loader, the transverse pressure output by the transverse static press, the temperature monitored by the temperature sensor, the seepage pressure flow rate and the acoustic emission signal (number of events, energy) collected by the acoustic emission monitoring sensor in real time, and performs signal filtering and analysis processing simultaneously. (4) The control system performs real-time calculations, using the degree of degradation D as the core evaluation index. The calculation formula is as follows:

[0040] Where E is the elastic modulus monitored in real time during the test, E0 is the initial elastic modulus, N is the number of real-time cumulative acoustic emission events, and N0 is the number of critical acoustic emission events (determined through indoor calibration tests, with a value range of 10). 4 ~10 6), α is a correction factor (related to the type of rock mass; for hard rock mass, α = 0.8-1.2; for soft rock mass, α = 1.2-1.5). Simultaneously, the rate of change of the seepage coefficient is used as an auxiliary criterion:

[0041] Where k is the real-time monitoring seepage coefficient, and k0 is the initial seepage coefficient; Finally, the degradation level is classified:

[0042] The criteria for classifying the degradation levels are as follows: Slight deterioration: When D < 0.3 and η > 0.5, the mechanical properties of the rock mass are slightly degraded, the internal microcracks are in the initial development stage, the seepage channels have not yet formed, the overall structure remains intact, and the slope is in a safe and stable state. Moderate deterioration: When 0.3≤D<0.7 and 0.5≤η<1.5, the mechanical properties of the rock mass decrease significantly, microcracks continue to expand and gradually penetrate, the seepage coefficient increases significantly, and the slope stability decreases significantly. It is necessary to intensify monitoring and carry out reinforcement measures. Critical failure: When D≥0.7 or η≥1.5, the mechanical properties of the rock mass are severely deteriorated, the crack network is basically connected, the seepage channel is fully formed, and the slope is on the verge of instability. (5) When the specimen enters the critical failure level, or reaches the preset number of test cycles and time, first turn off the pressurization function of the axial pressurizing cylinder, the high-frequency electro-hydraulic servo impact actuator and the transverse static pressurizer to unload the stress, then stop the temperature control of the freeze-thaw test chamber, turn off the direct shear coupling seepage pressurization device, cut off the seepage medium supply, and after the temperature in the pressure chamber drops to room temperature and the pressure is completely unloaded, take out the specimen, observe and record the specimen deterioration morphology (crack distribution, failure mode), organize the test data collected by the control system, and generate a test report containing multi-field parameter curves, deterioration index change curves and damage evolution cloud maps. If different parameters need to be tested, repeat steps (1) to (5).

[0043] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions conceived without inventive effort should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A water-thermal-mechanical coupled test system for assessing the deterioration of soil and rock mass on open-pit mine slopes, characterized in that, This includes an impact loader, a triaxial pressure chamber, a transverse static pressurizer, a freeze-thaw test chamber, a direct shear coupled seepage pressurization device, and a control system, among which: The impact loader has a triaxial pressure chamber in the middle, and transverse static presses are symmetrically arranged on both sides of the triaxial pressure chamber. A freeze-thaw test chamber and a direct shear coupled seepage pressurization device are connected to the outside of the triaxial pressure chamber. The impact loader, transverse static presses, freeze-thaw test chamber and direct shear coupled seepage pressurization device are all connected to a control system.

2. The water-thermal-mechanical coupled test system for assessing the deterioration of soil and rock mass on open-pit mine slopes as described in claim 1, characterized in that, The impact loader includes a body, an axial pressure cylinder, a high-frequency electro-hydraulic servo impact actuator, an impact rod, a magnetostrictive displacement sensor, and a base. The axial pressure cylinder is located at the top of the body, and its piston is connected to the impact rod for outputting a stable axial load. The high-frequency electro-hydraulic servo impact actuator, together with the impact rod, forms a dynamic loading module. Dynamic loading at different frequencies is achieved through servo valve control. The magnetostrictive displacement sensor is used to monitor the displacement signal of the impact rod in real time. The base is located at the bottom of the body.

3. The water-thermal-mechanical coupled test system for assessing the deterioration of soil and rock mass on open-pit mine slopes as described in claim 2, characterized in that, A three-axis pressure chamber is set in the middle of the machine body. A guide sleeve is set on the machine body above the three-axis pressure chamber. An impact rod is installed inside the guide sleeve. A drop hammer is set at the end of the impact rod. Hydraulic cylinders are symmetrically arranged on the machine body on both sides of the three-axis pressure chamber.

4. The water-thermal-mechanical coupled test system for assessing the deterioration of soil and rock mass on open-pit mine slopes as described in claim 3, characterized in that, The triaxial pressure chamber includes a support column and a double-layer shell. The double-layer shell is located on the upper side of the support column. The inner layer of the double-layer shell is a pressure-bearing cavity, and the outer layer is an insulation layer. There is a temperature-controlled interlayer between the inner and outer layers. The temperature-controlled interlayer has a temperature-controlled inlet and a temperature-controlled outlet for introducing temperature-controlled media. A transverse static press is located on both sides of the triaxial pressure chamber. The outer side of the double-layer shell is connected to the oil cylinder and the transverse static press through a pressure plate. An impact rod is connected to the top of the double-layer shell through a pressure plate.

5. The water-thermal-mechanical coupled test system for assessing the deterioration of soil and rock mass on open-pit mine slopes as described in claim 4, characterized in that, A seepage distribution plate is installed at the top of the support column. The seepage distribution plate is a porous plate structure with holes of different diameters in different areas to form differentiated seepage. Each hole on the seepage distribution plate is connected to an independent seepage pipe, and each seepage pipe is equipped with a solenoid valve.

6. The water-thermal-mechanical coupled test system for assessing the deterioration of soil and rock mass on open-pit mine slopes as described in claim 5, characterized in that, The triaxial pressure chamber is equipped with a temperature sensor and an acoustic emission monitoring sensor.

7. The water-thermal-mechanical coupled test system for assessing the deterioration of soil and rock mass on open-pit mine slopes as described in claim 6, characterized in that, The freeze-thaw test chamber is connected to the temperature control inlet and outlet of the triaxial pressure chamber via pipelines.

8. The water-thermal-mechanical coupled test system for assessing the deterioration of soil and rock mass on open-pit mine slopes as described in claim 7, characterized in that, The direct shear coupling seepage pressurization device includes a gas source, a gas booster pump, a constant pressure and constant speed pump, and a filter. The outlet of the gas source is connected to the inlet of the gas booster pump, the outlet of the gas booster pump is connected to the inlet of the constant pressure and constant speed pump, and the outlet of the constant pressure and constant speed pump is connected to the seepage pipe inlet at the bottom of the support column after passing through the filter.

9. The water-thermal-mechanical coupled test system for assessing the deterioration of soil and rock mass on open-pit mine slopes as described in claim 8, characterized in that, Pressure sensors are installed in both the impact loader and the transverse static press, while pressure and flow sensors are installed in the direct shear seepage pressurization device.

10. The test method of the water-thermal-mechanical coupled test system for assessing the deterioration of rock and soil in open-pit mine slopes as described in claim 9, characterized in that, The steps are as follows: (1) Select soil and rock mass, prepare standard specimens according to preset size, pre-treat the specimens, place the prepared specimens into the pressure chamber of the triaxial pressure chamber, position them with pressure plates to ensure that the specimens are placed in the center and in close contact with the upper and lower pressure surfaces, then seal the pressure chamber, connect the freeze-thaw test chamber to the temperature control inlet and temperature control outlet to complete the construction of the closed-loop temperature control circuit, connect the direct shear coupling seepage pressurization device through the seepage pipe interface, match the solenoid valve to realize seepage interruption control, arrange acoustic emission monitoring sensors and temperature sensors, and finally connect to the control system to complete the full system circuit network; (2) The test parameters are preset through the control system, and then the initial confining pressure and axial static load are applied to the specimen to simulate the in-situ stress state of the slope. The acoustic emission background signal and initial elastic wave velocity under low load are collected to establish the non-destructive state reference parameters. (3) After the formal test is started, the transverse static press applies transverse stress to the specimen at the preset pressure. The impact loader first applies axial static pressure through the axial pressurizing cylinder, and then outputs pulse impact load at the set frequency through the high-frequency electro-hydraulic servo impact actuator in conjunction with the impact rod to simulate the low-frequency vibration in the far zone of the explosion and the instantaneous impact in the near zone. The freeze-thaw test chamber is started and the temperature control medium is delivered to the temperature control interlayer of the pressure chamber. After the seepage medium is pressurized by the gas booster pump and filtered by the filter, it is delivered through the seepage pipe under the control of the solenoid valve and seeps into the interior of the specimen through the seepage distribution plate. During the test, the control system collects the impact load output by the impact loader, the transverse pressure output by the transverse static press, the temperature monitored by the temperature sensor, the seepage pressure flow rate and the acoustic emission signal data collected by the acoustic emission monitoring sensor in real time, and performs signal filtering and analysis processing simultaneously. (4) The control system performs real-time calculations, using the degree of degradation D as the core evaluation index. The calculation formula is as follows: ； Where E is the elastic modulus monitored in real time during the test, E0 is the initial elastic modulus, N is the number of real-time cumulative acoustic emission events, N0 is the number of critical acoustic emission events, and α is the correction coefficient. Simultaneously, the rate of change of the seepage coefficient is used as an auxiliary criterion: ； Where k is the real-time monitoring seepage coefficient, and k0 is the initial seepage coefficient; Finally, the degradation level is classified: ； The criteria for classifying the degradation levels are as follows: Slight deterioration: When D < 0.3 and η > 0.5, the mechanical properties of the rock mass are slightly degraded, the internal microcracks are in the initial development stage, the seepage channels have not yet formed, the overall structure remains intact, and the slope is in a safe and stable state. Moderate deterioration: When 0.3≤D<0.7 and 0.5≤η<1.5, the mechanical properties of the rock mass decrease significantly, microcracks continue to expand and gradually penetrate, the seepage coefficient increases significantly, and the slope stability decreases significantly. It is necessary to intensify monitoring and carry out reinforcement measures. Critical failure: When D≥0.7 or η≥1.5, the mechanical properties of the rock mass are severely deteriorated, the crack network is basically connected, the seepage channel is fully formed, and the slope is on the verge of instability. (5) When the specimen enters the critical failure level, or reaches the preset number of test cycles and time, first turn off the pressurization function of the axial pressurizing cylinder, the high-frequency electro-hydraulic servo impact actuator and the transverse static pressurizing machine to unload the stress, then stop the temperature control of the freeze-thaw test chamber, turn off the direct shear coupling seepage pressurizing device, cut off the seepage medium supply, and after the temperature in the pressure chamber drops to room temperature and the pressure is completely unloaded, take out the specimen, observe and record the specimen deterioration morphology, organize the test data collected by the control system, and generate a test report containing multi-field parameter curves, deterioration index change curves and damage evolution cloud maps.

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