A simulation test system and method for rockfall degradation and collapse under multi-field coupling.

Abstract

This invention provides a simulation test system and method for rock mass degradation and collapse under multi-field coupling. The system includes: a flexible stress loading device to provide vertical stress to the rock mass sample, making the sample have the same stress level as in its natural state; the rock mass sample, which simulates various collapse modes by controlling the angle of the weak zone and the erosion zone; a corrosion device to provide the rock mass sample with a wet-dry cycle and osmotic pressure environment; a data acquisition device to record the surface displacement, acoustic characteristics, and external factors of the rock mass along the weak zone; a damage degree calculation device to calculate the damage degree of the rock mass under multi-field coupling; a safety factor calculation device to obtain the safety factor of the rock mass under multi-field coupling; and a safety assessment device to construct an assessment model and assess the safety status of the rock mass. This invention realizes the simulation of collapse caused by the degradation of the weak zone under multi-field coupling, and solves the problem of early safety assessment and graded early warning of rock mass instability based on multi-index fusion.

Description

Technical Field

[0001] This invention relates to the field of rock mass prevention and control technology, and in particular to a simulation test system and method for rock mass deterioration and collapse under multi-field coupling. Background Technology

[0002] Rockfalls, a common geological hazard in mountainous areas, are characterized by their suddenness, destructive force, and wide impact, often posing a serious threat to the lives and property of surrounding residents, transportation infrastructure, and the ecological environment. The deterioration and collapse of rockfalls are the result of the combined effects of multiple fields, including stress, seepage, and chemical fields. Under natural conditions, in addition to bearing its own gravity, rock masses are also subject to wet-dry cycles caused by rainwater infiltration and groundwater activity. This brings the weak zones within the rock mass into contact with chemically corrosive solutions (such as water carrying acidic substances), altering the mineral composition and damaging the structure of these weak zones, thus reducing their shear strength. Simultaneously, the long-term effects of stress and the cumulative effects of chemical corrosion promote the continuous initiation and expansion of micro-fractures in the weak zones, ultimately leading to the sliding collapse of the rockfall along these weak zones. Furthermore, the structural stability of rockfalls varies significantly depending on the angle of the weak zones, and their collapse modes (such as sliding, toppling, and falling) also differ fundamentally, necessitating targeted simulation and research.

[0003] However, current simulation technologies for rockfall degradation and collapse still have many shortcomings, making it difficult to meet the needs of research on rockfall disaster mechanisms and accurate early warning under multi-field coupling: First, existing stress loading devices are mostly rigid loading structures, which are difficult to accurately simulate the stress distribution of rock masses under natural conditions. During loading, local stress concentration is easily generated, and the need for non-uniform deformation of the sample cannot be met, leading to significant deviations between experimental results and actual working conditions. Second, most experimental systems can only simulate stress or chemical corrosion effects individually, lacking accurate simulation of the synergistic effects of wet-dry cycles and chemical corrosion, especially the high osmotic pressure environment from the inside out. Therefore, they cannot reproduce the real process of rockfall degradation under multi-field coupling. Third, existing technologies have not established multi-field... The quantitative model of residual shear strength in the weak zone of the rock mass under coupling effects results in a lack of mechanical support for assessing the degree of deterioration of dangerous rock masses, with the weak zone controlling instability. Fourth, the data acquisition system is incomplete, mostly limited to monitoring single physical quantities (such as deformation), lacking synchronous monitoring of key indicators such as acoustic characteristics (such as changes in sound wave propagation speed, which can reflect the degree of damage inside the rock mass) and ion concentration (which can characterize the intensity of chemical corrosion). As a result, the safety assessment of dangerous rock masses is mostly based on single damage indicators, failing to construct a damage model that integrates multiple indicators. This makes it impossible to achieve a chain-like study of "multi-field coupling simulation - multi-indicator synchronous monitoring - residual shear strength calculation - safety status assessment", which in turn affects the rationality of the early warning threshold setting and the accuracy of the early warning. Summary of the Invention

[0004] To address the problems in the prior art, this invention provides a simulation test system and method for rockfall degradation and collapse under multi-field coupling. First, a flexible stress loading device provides vertical stress to the rock mass sample, ensuring it has the same stress level as in its natural state. Second, by altering the angle of the weak zone and the hollowed-out area of ​​the rock mass sample, simulations of various collapse modes are achieved. Third, a cyclic corrosion device provides the rock mass sample with an external wet-dry cycle environment and an internal high-osmotic-pressure environment, allowing the corrosive solution to flow within the weak zone. Fourth, a data acquisition device monitors the surface displacement, acoustic characteristics, ion concentration, and mechanical properties of the unstable rock mass along the weak zone. Finally, simulation tests of rockfall degradation and collapse under multi-field coupling are conducted to obtain the rock mass fracture surface, shear strength, safety factor, and safety assessment method.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0006] A simulation test system for the deterioration and collapse of unstable rock under multi-field coupling includes: a flexible stress loading device, an unstable rock mass sample, a corrosion device, a data acquisition device, a damage degree calculation device, a safety factor calculation device, and an unstable rock mass safety assessment device.

[0007] The flexible stress loading device provides vertical stress to the unstable rock mass sample so that the unstable rock mass sample has the same stress level as the natural state. The flexible loading allows uneven deformation of the contact surface.

[0008] The unstable rock mass sample is installed in the flexible stress loading device and is divided into stable rock mass and unstable rock mass by the weak zone. By changing the angle of the weak zone in different unstable rock mass samples, and combining it with the scouring of the weak zone outlet to form a hollowed-out zone of different degrees, it is possible to make unstable rock mass samples under sliding, tilting and falling collapse modes. By making different unstable rock mass samples, it is possible to realize the test simulation of multiple collapse modes.

[0009] The corrosion device is installed below the flexible stress loading device. It provides a dry-wet cycle environment for the unstable rock mass sample from the outside, causing corrosion and deterioration on the surface of the unstable rock mass, and provides an osmotic pressure environment for the unstable rock mass sample from the inside, causing corrosion and deterioration in the weak zone inside the unstable rock mass under the action of seepage.

[0010] The data acquisition device is used to record the surface displacement, acoustic characteristics, and external factors of the rock mass along the weak zone. The external factors include the types and concentrations of corrosive ions, osmotic pressure, vertical stress, number of wet-dry cycles, and time.

[0011] The damage degree calculation device is used to calculate the location of the fracture point in the weak zone of the rock mass based on the acoustic characteristics collected by the data acquisition device, construct a through fracture surface based on the location of the fracture point, obtain a damage model based on the through fracture surface, and further calculate the damage degree of the dangerous rock mass under multi-field coupling.

[0012] The safety factor calculation device is used to obtain the residual shear strength test value of the weak zone of the rock mass under multi-field coupling based on the vertical stress when the unstable rock mass sample is unstable, and to obtain the relationship model between the residual shear strength test value and the external factors based on the residual shear strength test value under multiple sets of external factors. Based on the relationship model and the specific external factors of the unstable rock mass, the device predicts the residual shear strength under the specific external factors, and further obtains the safety factor based on the residual shear strength prediction value under the specific external factors, the volume and shape of the unstable rock mass.

[0013] The safety assessment device is used to assess the safety status of dangerous rock masses and provide graded early warnings by constructing an assessment model based on the safety factor and the degree of damage.

[0014] Furthermore, the flexible stress loading device includes a hydraulic pillow, a high-pressure oil pump, a pad, a ball bearing system, and a reaction frame;

[0015] The hydraulic pillow is placed on the top surface of the unstable rock mass sample. The flexible characteristics of the hydraulic pillow are used to apply flexible pressure to the top surface, so that the top surface can undergo uneven deformation under the action of flexible pressure and the sliding action of weak zone.

[0016] The reaction frame, used to provide reaction force for the hydraulic pillow, is a 12-sided steel frame welded from structural steel. A thick steel plate is arranged on the top and bottom of the reaction frame as a top plate and a bottom plate, respectively. The four side columns on the side of the 12-sided steel frame can extend and retract vertically to adjust the height of the reaction frame according to the height of the unstable rock mass sample.

[0017] The pad is used to fill the gap between the hydraulic pillow and the reaction frame;

[0018] The ball bearing system is used to enable the hydraulic pillow to move horizontally;

[0019] The high-pressure oil pump is used to provide high-pressure hydraulic oil to the hydraulic pillow, and an oil pressure gauge is installed at the oil outlet of the high-pressure oil pump to monitor the flexible pressure.

[0020] Furthermore, the unstable rock mass sample is divided into stable rock mass and unstable rock mass by weak zones. According to the different angles of the weak zones and the different degrees of hollowing, various samples with different weak zone angles and different degrees of hollowing are made to simulate various collapse modes. The various collapse modes include sliding, toppling and falling.

[0021] The side of the unstable rock mass sample has a water injection hole, which is used to provide an osmotic pressure environment for the unstable rock mass sample from the inside, so as to cause corrosion and deterioration of the weak zone inside the unstable rock mass under the action of seepage.

[0022] Furthermore, the corrosion device includes a dry-wet circulation device, a high-pressure permeation device, a high-pressure flushing device, and a corrosion solution;

[0023] The dry-wet circulation device is used to provide a dry-wet circulation environment for the unstable rock mass sample from the outside, which causes corrosion and deterioration on the surface of the unstable rock mass.

[0024] The high-pressure permeation device is used to provide an osmotic pressure environment for the unstable rock mass sample from the inside, thereby reducing corrosion and deterioration caused by seepage inside the unstable rock mass.

[0025] The high-pressure scouring device is used to provide high-pressure water erosion flow to the weak zone outlet position when conducting the tilting and falling collapse mode tests on the unstable rock mass sample, so as to create a local erosion zone at the weak zone outlet position.

[0026] The corrosive solution is a mixed solution composed of different types of corrosive ions and their corresponding concentrations.

[0027] Furthermore, the dry-wet cycle device includes: a corrosion tank, a solution storage tank, a water pump, a water pumping pipe, a drain pipe, and a solenoid valve;

[0028] The water pump is located inside the solution storage tank and is connected to the corrosion tank via the water pumping pipe;

[0029] The solution storage tank is used to store the corrosive solution and is connected to the corrosion tank through the drain pipe. The drain pipe is equipped with the solenoid valve to control the opening and closing state of the drain pipe.

[0030] The water pump and the solenoid valve work alternately to provide a dry-wet cycle corrosion environment for the corrosion chamber;

[0031] The high-pressure permeation device includes a first high-pressure water pump, a first inlet pipe, a first outlet pipe, a self-sealing water injection head, and a water pressure sensor.

[0032] The first high-pressure water pump is connected to the solution storage tank through the first water inlet pipe;

[0033] The first high-pressure water pump is connected to the self-sealing water injection head through the first water outlet pipe;

[0034] The self-sealing water injection head is installed in the water injection hole of the unstable rock mass sample;

[0035] The self-sealing water injection head can inject high-pressure corrosion solution into the water injection hole, and the self-sealing function prevents the high-pressure corrosion solution from flowing out of the hole along the water injection hole.

[0036] The self-sealing water injection head includes an inner hollow steel pipe and an outer rubber sleeve. The outer rubber sleeve wraps around the outside of the inner hollow steel pipe to form a cavity. The outer rubber sleeve and the inner hollow steel pipe have a communication hole for allowing the pressurized corrosive solution to enter the cavity. The outer rubber sleeve then uses water pressure to adhere to the inner wall of the injection hole to form resistance, thereby achieving a self-sealing function.

[0037] The high-pressure corrosion solution can penetrate into the unstable rock mass sample;

[0038] The first high-pressure water pump is used to provide osmotic pressure to the inside of the unstable rock mass sample. The first high-pressure water pump is equipped with a water pressure sensor at the outlet position. The water pressure sensor is used to record the osmotic pressure provided by the first high-pressure water pump to the inside of the unstable rock mass sample.

[0039] The high-pressure flushing device includes a second high-pressure water pump, a second inlet pipe, a second outlet pipe, and a spray gun.

[0040] The second high-pressure water pump is connected to the solution storage tank through the second water inlet pipe;

[0041] The second high-pressure water pump is connected to the spray gun through the second outlet pipe;

[0042] The spray gun is fixed to the reaction frame, and the outlet is facing the weak zone outlet position;

[0043] The second high-pressure water pump is used to provide high water pressure to the spray gun to erode the weak zone outlet position, thereby forming a hollowed-out area.

[0044] Furthermore, the data acquisition device includes a DIC deformation measurement system, an acoustic emission measurement system, an ion meter, and a data logger;

[0045] The DIC deformation measurement system is installed on the side wall of the corrosion chamber, facing the surface of the unstable rock mass sample, and is used to measure the surface displacement, strain distribution and image data of the collapse process of the unstable rock mass sample.

[0046] The acoustic emission measurement system is deployed on two opposite sides of the unstable rock mass sample, with one system deployed diagonally on each side, to monitor the acoustic characteristics when the weak zone ruptures.

[0047] The ion meter is installed at the bottom of the corrosion chamber and is used to determine the types of ions and their corresponding concentrations in the solution.

[0048] The data logger is used to record the monitoring data of the DIC deformation measurement system, the acoustic emission measurement system and the ion meter, as well as the osmotic pressure, the vertical stress, the number of wet-dry cycles and the time during the test.

[0049] Furthermore, the damage degree calculation device is specifically used for:

[0050] S61: Placement of acoustic emission probes: Place 4 acoustic emission probes on two opposite sides of the square sample. Select two opposite corners on each side and place one probe on each side. Place a total of 2 probes on each side, and denoted as side A and side B.

[0051] S62: Define a three-dimensional coordinate system: with the lower left corner probe of side A as the origin O(0,0,0), the x-axis is horizontally to the right along side A, the y-axis is horizontally from side A to side B, and the z-axis is vertically upward along side A.

[0052] S63: Determine the coordinates of each probe: Let the horizontal distance between two probes on the same side be L, the distance between two sides be W, and the vertical distance between two probes on the same side be H. Then the coordinates of the four probes can be defined as follows: Side A: Probe P1 (0,0,0), Probe P2 (L,0,H); Side B: Probe P3 (L,W,0), Probe P4 (0,W,H);

[0053] S64: Solving for the distance between the rupture point and the probe: Let the three-dimensional coordinates of the rupture point be S(x,y,z), and the acoustic emission signal propagates from S to the i-th probe P. ᵢ The time is t ᵢ Then the signal propagation distance d ᵢ With time t ᵢ satisfy:

[0054] (1);

[0055] In the formula, v is the speed of sound wave propagation;

[0056] S65: Calculate the time difference of each probe: Based on the arrival time difference of the signals received by the four probes, take the probe that first receives the acoustic emission signal as the time reference, denoted as t0, and calculate the time difference of the other three probes relative to the reference probe:

[0057] (2);

[0058] S66: Construct a three-dimensional coordinate equation system: from the rupture point S(x,y,z) to any two probes P ᵢ P ⱼ The distance difference satisfies:

[0059] (3);

[0060] Probe P ᵢ The distance to any point is:

[0061] (4);

[0062] Substituting equation (4) into equation (3), and selecting three independent probe combinations, such as P1 and P2, P1 and P3, and P1 and P4, we obtain the three-dimensional coordinate equation system:

[0063] (5);

[0064] S67: Solve for the coordinates of the rupture point: Based on the iterative fitting of multiple sets of data, the "Newton-Raphson iteration method" is used to solve formula (5) to obtain the coordinates S(x,y,z) of the rupture point;

[0065] S68: Constructing the fracture surface: By continuously monitoring multiple sets of acoustic emission signals, the coordinates of multiple fracture points S1(x1,y1,z1), S2(x2,y2,z2), ..., S n (x n ,y n ,z n ), where n is a natural number greater than or equal to 3, and the least squares method is used to fit the equation of the rupture surface:

[0066] ax+by+cz+d=0 (6);

[0067] Where a, b, c, and d are fitting coefficients that minimize the sum of the squared distances from all fracture points to the plane. The plane equation is obtained through fitting, and the area s of the fracture surface in the square specimen is obtained by using the outermost fracture point on the plane as the boundary. t ;

[0068] S69: Constructing the damage model: Based on the fracture surface area and the initial area s0 of the weak zone in the sample, the damage model is obtained:

[0069] (7);

[0070] S610: Based on the damage model, the degree of damage at time t is calculated using the cumulative acoustic emission signal at time t. .

[0071] Furthermore, the safety factor calculation device is specifically used for:

[0072] S71: Select five external factors as independent variables, design an orthogonal experiment with five independent variables and four levels, and use Lo... 16 (45 Orthogonal experimental tables were used, and orthogonal experimental tests were conducted to calculate the residual shear strength test value for each combination. The five external factors included: the type and corresponding concentration of corrosive ions, osmotic pressure, vertical stress, number of wet-dry cycles and time. The residual shear strength test value was calculated based on the vertical stress on the top surface of the unstable rock mass, the area of ​​the top surface, the angle of the weak zone, and the area of ​​the weak zone when the unstable rock mass underwent sliding failure.

[0073] S72: Normalize the independent variables and map them uniformly to the [0,1] interval to eliminate the differences in the dimensions and value ranges of the five independent variables; among them, the normalized value of the number of wet-dry cycles is X1, the normalized value of the types of corrosive ions and their corresponding concentrations is X2, the normalized value of vertical stress is X3, the normalized value of osmotic pressure is X4, and the normalized value of time is X5.

[0074] S73: Establish a model relating five normalized values ​​to residual shear strength test values:

[0075] (8);

[0076] In the formula, This represents the residual shear strength test value; This represents the initial shear strength of the weak zone. is a natural constant; a, b, c, d, and f are the main effect weights of their respective independent variables, determined through regression fitting of experimental data. The larger the weight, the greater the impact of the independent variable on the dependent variable. The more significant the effect, the greater the impact; g, h, m, and n are the interaction coefficients between the two factors, reflecting the influence of the synergistic effect of the independent variables on the dependent variable;

[0077] S74: Based on the results of 16 orthogonal experiments, the least squares method was used to fit the model parameters, obtaining parameters a, b, c, d, f, g, h, m, and n, which were then substituted back into the relational model. Five normalized values ​​and predicted residual shear strength were obtained. Relational model expression:

[0078] (9);

[0079] S75: Based on the five actual external factors of the unstable rock mass and the relational model expression (9), the predicted value of the residual shear strength under these external factors is obtained. ;

[0080] S76: Predicted residual shear strength based on the volume and shape of the unstable rock mass and the external factors. The safety factor F of the unstable rock mass is calculated using the strength reduction method or the limit equilibrium method.

[0081] Furthermore, the safety assessment device is specifically used for:

[0082] S81: Extract safety factor based on test data and damage severity indicators ;

[0083] S82: A comprehensive evaluation model is constructed using a combination of weighted fusion and threshold determination.

[0084] (10);

[0085] In the formula, ; For comprehensive evaluation index; The weight of the safety factor The weight assigned to the degree of damage;

[0086] S83: Based on the comprehensive evaluation index and in accordance with the evaluation rules, the safety status is obtained. The evaluation rules are as follows:

[0087] when At this time, it is at Level I, extremely safe, with no warning, and is in a stable state. It is characterized by slight deterioration, no risk of instability, and good long-term safety. Continuous monitoring is sufficient.

[0088] when At present, Level II is relatively safe. Blue alert, low risk, basically stable, with slight deterioration. There is no risk of instability in the short term, but long-term attention should be paid to the accumulation of deterioration.

[0089] when At that time, Level III, critical safety, yellow warning, medium risk, is a critical stable state with obvious deterioration, local minor cracks, and may exacerbate the risk of instability under extreme working conditions;

[0090] when At that time, it was classified as Level IV, an unstable state, with a red alert and high risk. It was an unstable state with severe deterioration, and the rupture surface had been connected or developed over a large area, posing an immediate risk of instability and collapse.

[0091] A method for simulating the deterioration and collapse of unstable rock under multi-field coupling, wherein the test method utilizes the system described above and includes the following steps:

[0092] (1) Prepare rock mass specimens: Select rock mass in its natural state containing a weak zone. When simulating a sliding collapse mode, design the angle of the weak zone to be less than 90°. When simulating a toppling collapse mode or a falling collapse mode, design the angle of the weak zone to be equal to or greater than 90°. Cut out a square rock mass specimen containing a weak zone according to the designed angle of the weak zone.

[0093] (2) Install flexible stress loading device: Use steel profiles to weld a 12-sided frame that can be extended vertically. Place a thick steel plate on the top and bottom of the reaction frame as the top plate and bottom plate respectively. Place the unstable rock mass sample on the bottom plate. Place the hydraulic pillow, pad block and ball bearing row on the unstable rock mass sample in sequence. Adjust the height of the frame so that the ball bearing row contacts the top plate. Connect the hydraulic pillow and high pressure oil pump with high pressure oil pipe.

[0094] (3) Install the corrosion device: Connect the solution storage tank, water pump, water pipe, drain pipe, and solenoid valve to the corrosion tank to complete the installation of the dry-wet cycle device; connect the first high-pressure water pump, the first water inlet pipe, the first water outlet pipe, and the water pressure sensor to the self-sealing water injection head, and install the self-sealing water injection head to the water injection hole of the unstable rock mass sample to complete the installation of the high-pressure permeation device; connect the second high-pressure water pump, the second water inlet pipe, and the second water outlet pipe to the spray gun, and install the spray gun on the side of the reaction frame and aim it near the rock layer outlet of the unstable rock mass sample to complete the installation of the high-pressure flushing device;

[0095] (4) Install data acquisition device: Place 4 acoustic emission probes on two opposite sides of the square sample, and place 1 probe on each of the two opposite corners of each side, for a total of 2 probes on each side, denoted as side A and side B; place the DIC deformation measurement system on the side wall of the corrosion chamber, facing the surface of the unstable rock sample; place the ion meter at the bottom of the corrosion chamber; connect the above devices to the data logger using a data cable;

[0096] (5) Scouring to form a hollow zone: When simulating the collapse mode, a high-pressure scouring device is used to scour the weak zone outlet to form a hollow zone, but the hollow zone is not connected with the weak zone; when simulating the collapse mode, a high-pressure scouring device is used to scour the weak zone outlet to form a hollow zone, and the hollow zone is connected with the weak zone.

[0097] (6) Conduct collapse simulation test: Set 5 external factors: the type and corresponding concentration of corrosive ions, osmotic pressure, vertical stress, number of wet and dry cycles and time, conduct test work, and record the residual shear strength test data;

[0098] (7) Calculate the damage degree of the dangerous rock mass under multi-field coupling: Calculate the location of the fracture point in the weak zone of the rock mass based on the acoustic characteristics collected by the acoustic emission measurement system, construct the through fracture surface based on the location of the fracture point, and obtain the damage model based on the through fracture surface to further calculate the damage degree of the dangerous rock mass under multi-field coupling.

[0099] (8) Calculate the safety factor: Based on the vertical stress when the unstable rock mass sample is unstable, obtain the residual shear strength test value of the weak zone of the rock mass under multi-field coupling, and based on the residual shear strength test value under multiple sets of external factors, obtain the relationship model between the residual shear strength test value and the external factors, and based on the relationship model and the specific external factors of the unstable rock mass, predict the residual shear strength under the specific external factors, and further obtain the safety factor based on the residual shear strength prediction value under the specific external factors, the volume and shape of the unstable rock mass;

[0100] (9) Safety assessment: Based on the safety factor and the degree of damage, an assessment model is constructed to assess the safety status of the dangerous rock mass and to conduct graded early warning.

[0101] Compared with the prior art, the technical solution of the present invention has at least the following beneficial effects:

[0102] Firstly, by applying flexible vertical stress, a 1:1 gravity simulation of the test model and the natural state of the unstable rock mass on site was achieved, which is more consistent with the failure characteristics of the rock mass under mechanical action and solves the problem that the indoor test model does not match the stress state of the original rock on site.

[0103] Secondly, by controlling the angle of the natural weak zone and the hollowed-out area in the model, the slip mode of the weak zone can be changed, which solves the problem of making model specimens containing natural weak zones when simulating different failure modes, and realizes the simulation of the failure process of multiple instability modes.

[0104] Thirdly, by designing a water-mechanical-chemical dissolution coupled environment, a two-way corrosion water flow condition of infiltration from the inside out and external circulation was formed, realizing the indoor test simulation of the entire process of water-related unstable rock mass from formation to deterioration to instability in a real environment;

[0105] Fourthly, by simultaneously monitoring acoustic, mechanical, and environmental indicators, the damage level and safety factor of the unstable rock mass were obtained. Based on this, a dual-indicator safety assessment model of "safety factor + damage level" was constructed. Through weighted fusion calculation of the comprehensive assessment index, a closed-loop research system of "deterioration parameter calculation - stability index quantification - safety status assessment - risk classification and early warning" was formed, realizing the graded assessment and accurate early warning of the safety status of the unstable rock mass. Attached Figure Description

[0106] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0107] Figure 1 is a schematic diagram of the overall structure of an embodiment of the simulation test system for rockfall degradation and collapse under multi-field coupling provided by the present invention;

[0108] Figure 2 is a schematic diagram of the flexible loading device of an embodiment of the simulation test system for rockfall degradation and collapse under multi-field coupling of the present invention;

[0109] Figure 3 is a schematic diagram of a rock mass sample in an embodiment of the simulation test system for rock mass deterioration and collapse under multi-field coupling of the present invention;

[0110] Figure 4 is a schematic diagram of the corrosion device of an embodiment of the simulation test system for rockfall degradation and collapse under multi-field coupling of the present invention;

[0111] Figure 5 is a schematic diagram of the data acquisition device of an embodiment of the simulation test system for rockfall degradation and collapse under multi-field coupling of the present invention;

[0112] Figure 6 is a schematic diagram of the self-sealing water injection head of an embodiment of the simulation test system for rockfall degradation and collapse under multi-field coupling of the present invention;

[0113] Figure 7 This is a flowchart of the implementation steps of the simulation test method for the deterioration and collapse of dangerous rocks under multi-field coupling effect of the present invention.

[0114] Explanation of reference numerals in the attached figures:

[0115] 1. Flexible stress loading device; 2. Rock mass sample; 3. Corrosion device; 4. Data acquisition device; 5. Damage degree calculation device; 6. Safety factor calculation device; 7. Safety assessment device; 8. Hydraulic pillow; 101. High-pressure oil pump; 102. Pad block; 103. Ball bearing plate; 104. Reaction frame; 105. Weak zone; 201. Water injection hole; 202. Hollowed-out zone; 203. Stable rock mass; 204. Unstable rock mass; 205. Corrosion chamber; 301. Solution storage tank; 302. Water pump; 303. Water pumping pipe; 304. Drainage pipe 305, solenoid valve 306, first high-pressure water pump 307, first inlet pipe 308, first outlet pipe 309, self-sealing water injection head 310, hollow steel pipe 3101, rubber sleeve 3102, water pressure sensor 311, second high-pressure water pump 312, second inlet pipe 313, second outlet pipe 314, spray gun 315, corrosive solution 316, DIC deformation measurement system 401, acoustic emission measurement system 402, ion meter 403, data logger 404. Detailed Implementation

[0116] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0117] In embodiments of the present invention, words such as "exemplarily" and "for example" are used to indicate that something is an example, illustration, or description. Any embodiment or design described as "exemplary" in the present invention should not be construed as being more preferred or advantageous than other embodiments or designs. Rather, the use of the term "exemplary" is intended to present the concept in a specific manner.

[0118] like Figure 1 The diagram shows an overall structural schematic of an embodiment of the simulation test system for the deterioration and collapse of unstable rock under multi-field coupling of the present invention. The system includes: a flexible stress loading device 1, an unstable rock mass sample 2, a corrosion device 3, and a data acquisition device 4.

[0119] The flexible stress loading device 1 is used to provide vertical stress to the unstable rock mass sample 2 so that the unstable rock mass sample 2 has the same stress level as the natural state. It can restore the natural gravity in the room by using flexible loading in accordance with the gravity of the unstable rock mass in the natural state. The flexible loading allows uneven deformation of the contact surface. For example, in the tilting and falling collapse mode, the unstable rock mass is allowed to slide along the weak zone 201, while the unstable part remains unchanged in displacement.

[0120] The unstable rock mass sample 2 is installed below the hydraulic cushion 101 of the flexible stress loading device 1, and flexible pressure is applied to its upper surface by the hydraulic cushion 101; the unstable rock mass sample 2 is divided into stable rock mass 204 and unstable rock mass 205 by the weak zone; by changing the angle of the weak zone in different unstable rock mass samples 2, combined with the scouring of the outlet of the weak zone 201, different degrees of hollowing zone 203 are formed, thereby realizing the stress on the sliding ( Figure 3 (a) and tilting type ( Figure 3 (b) and falling ( Figure 3 The preparation of unstable rock mass sample 2 under the collapse mode in (c) shows that by preparing different unstable rock masses, it is possible to simulate multiple collapse modes.

[0121] The angle of the weak zone is the angle between the weak zone 201 and the horizontal plane;

[0122] When the angle of the weak zone of the unstable rock mass sample 2 is less than 90°, it is a sliding collapse mode;

[0123] When the angle of the weak zone of the unstable rock mass sample 2 is equal to or greater than 90° and there is a hollowed-out area at the outlet of the weak zone, but the hollowed-out area is not connected to the weak zone, it is a tilting collapse mode.

[0124] When the angle of the weak zone of the unstable rock mass sample 2 is equal to or greater than 90° and there is a hollowed-out area at the outlet of the weak zone, the hollowed-out area is connected to the weak zone, which is a falling collapse mode.

[0125] The corrosion device 3, installed below the flexible stress loading device 1, is capable of accommodating the flexible stress loading device 1. Firstly, it provides a wet-dry cycle environment for the unstable rock mass sample from the outside, causing corrosion and deterioration on the surface of the unstable rock mass. Secondly, it provides an osmotic pressure environment for the unstable rock mass sample from the inside, causing corrosion and deterioration under seepage action inside the unstable rock mass. Thirdly, a second high-pressure water pump 312 is used to flush the outlet position of the weak zone of the unstable rock mass sample 2, simulating the formation process of the hollowed-out zone of the unstable rock mass sample 2 in its natural state, thereby simulating various collapse modes.

[0126] The data acquisition device 4 is used to monitor the surface displacement, acoustic characteristics, and external factors of the weak zone in the unstable rock mass sample 2. The external factors include the type and concentration of corrosive ions, osmotic pressure, vertical stress, number of wet-dry cycles, and time.

[0127] The damage degree calculation device 5 is used to calculate the location of the fracture point in the weak zone of the rock mass based on the acoustic features collected by the data acquisition device 4, construct a through fracture surface based on the location of the fracture point, obtain a damage model based on the through fracture surface, and further calculate the damage degree of the dangerous rock mass under multi-field coupling.

[0128] The safety factor calculation device 6 is used to obtain the residual shear strength test value of the weak zone 201 of the rock mass under multi-field coupling based on the vertical stress of the weak zone 201 when the unstable rock mass sample 2 is unstable, and to obtain the relationship model between the residual shear strength test value and the external factors based on the residual shear strength of multiple sets of tests and external factors. Based on the relationship model and the specific external factors of the unstable rock mass, the device predicts the residual shear strength under the specific external factors, and further obtains the safety factor based on the residual shear strength prediction value under the specific external factors, the volume and shape of the unstable rock mass.

[0129] The safety assessment device 7 is used to construct an assessment model based on the safety factor and the degree of damage to assess the safety status of the dangerous rock mass and to provide graded early warning.

[0130] Specifically, such as Figure 2The diagram shows a schematic of a flexible loading device in an embodiment of the multi-field coupling simulation test system for rockfall degradation and collapse of the present invention. The flexible stress loading device 1 includes: a hydraulic pillow 101, a high-pressure oil pump 102, a pad 103, a ball bearing assembly 104, and a reaction frame 105.

[0131] The hydraulic pillow 101 is placed on the upper surface of the unstable rock mass sample 2, and the pad 103 is placed on the hydraulic pillow 101. By selecting pads 103 of different thicknesses, the gap between the unstable rock mass sample 2 and the reaction frame 105 can be filled.

[0132] The hydraulic pillow 101 is slightly smaller than the top surface of the unstable rock mass sample 2 to prevent the bottom surface of the hydraulic pillow 101 from being damaged due to the loss of the reverse constraint of the top surface of the unstable rock mass sample 2.

[0133] The ball bearing 104 is arranged on the pad 103 and contacts the reaction frame 105. It is used to make the rock mass sample 2 slide between the reaction frame 105 and the rock mass sample 2, so as to prevent the reaction frame 105 from hindering the horizontal deformation of the rock mass sample 2.

[0134] The high-pressure oil pump 102 is connected to the hydraulic pillow 101 and provides high-pressure hydraulic oil to the hydraulic pillow 101 to meet the pressure applied by the hydraulic pillow 101 to the unstable rock mass sample 2.

[0135] The reaction frame 105 is a 12-sided steel frame welded from structural steel. A thick steel plate is arranged on the top and bottom of the reaction frame 105 as the top plate and bottom plate, respectively, to provide reaction force for the hydraulic pillow 101. The four side columns on the side of the 12-sided steel frame can extend and retract vertically to adjust the height of the reaction frame 105 according to the height of the unstable rock mass sample 2.

[0136] Specifically, such as Figure 3 The diagram shown is a schematic diagram of a rock mass sample in an embodiment of the multi-field coupling simulation test system for rock mass deterioration and collapse of the present invention. The rock mass sample 2 includes: a weak zone 201, a water injection hole 202, and a hollowed-out zone 203.

[0137] The weak zone 201 is located in the middle of the unstable rock mass sample 2. When making the cuboid sample, unstable rock mass samples 2 with different dip angles containing the weak zone 201 are made by controlling the cutting boundary.

[0138] When simulating a sliding collapse mode, the angle of the weak zone is designed to be less than 90°; when simulating a toppling collapse mode or a falling collapse mode, the angle of the weak zone is designed to be equal to or greater than 90°.

[0139] A water injection hole 202 is opened in the middle of the upper half of the unstable rock mass sample 2 to provide an osmotic pressure environment for the unstable rock mass sample from the inside, so as to cause corrosion and deterioration of the weak zone 201 inside the unstable rock mass under the action of seepage.

[0140] When simulating a tilting collapse mode, the spray gun 315 is used to flush out the hollowed-out area at the outlet of the weak zone 201, but the hollowed-out area is not connected to the weak zone 201; when simulating a falling collapse mode, the spray gun 315 is used to flush out the hollowed-out area at the outlet of the weak zone 201, and the hollowed-out area is connected to the weak zone 201.

[0141] By controlling the dip angle and hollowing-out area of ​​the weak zone 201, it is possible to produce unstable rock mass specimen 2 that meets the sliding, tilting, and falling collapse modes.

[0142] Specifically, such as Figure 4 The schematic diagram shown is of a corrosion device in an embodiment of the multi-field coupling simulation test system for rockfall degradation and collapse of the present invention. The corrosion device 3 includes:

[0143] Corrosion chamber 301, solution storage tank 302, water pump 303, water pumping pipe 304, drain pipe 305, solenoid valve 306, first high-pressure water pump 307, first water inlet pipe 308, first water outlet pipe 309, self-sealing water injection head 310, water pressure sensor 311, second high-pressure water pump 312, second water inlet pipe 313, second water outlet pipe 314, spray gun 315, corrosion solution 316.

[0144] The corrosion chamber 301, solution storage tank 302, water pump 303, water pumping pipe 304, drainage pipe 305 and solenoid valve 306 constitute a dry and wet circulation device, which is used to provide a dry and wet circulation environment for the dangerous rock mass sample from the outside, and to cause corrosion and deterioration on the surface of the dangerous rock mass.

[0145] The corrosive solution 316 is a mixed solution composed of different types and corresponding concentrations of corrosive ions, and is stored in the solution storage tank 302;

[0146] The water pump 303 is located inside the solution storage tank 302 and is connected to the corrosion tank 301 via the water pumping pipe 304, and is used to inject the corrosion solution into the corrosion tank 301.

[0147] The solution storage tank 302 is connected to the corrosion tank 301 via a drain pipe 305, which is used to discharge the corrosion solution in the corrosion tank 301 to the solution storage tank 302. A solenoid valve 306 is installed on the drain pipe 305 to control the opening and closing state of the drain pipe 305. By alternating the operation of the water pump 303 and the solenoid valve 306, a dry and wet cycle corrosion environment is provided for the unstable rock sample 2 in the corrosion tank 301.

[0148] The first high-pressure water pump 307, the first inlet pipe 308, the first outlet pipe 309, the self-sealing water injection head 310, the hollow steel pipe 3101, the rubber sleeve 3102 and the water pressure sensor 311 constitute a high-pressure permeation device, which is used to provide an osmotic pressure environment for the unstable rock mass sample from the inside, and to generate corrosion and deterioration under the seepage action inside the unstable rock mass.

[0149] The first high-pressure water pump 307 is used to provide the seepage water pressure inside the unstable rock mass sample 2; a water pressure sensor 311 is installed at the outlet of the first high-pressure water pump 307 to monitor the seepage water pressure provided by the first high-pressure water pump 307 to the inside of the unstable rock mass sample 2.

[0150] The first high-pressure water pump 307 is connected to the solution storage tank 302 through the first inlet pipe 308; the first high-pressure water pump 307 is connected to the self-sealing water injection head 310 through the first outlet pipe 309; the self-sealing water injection head 310 is installed in the water injection hole 202 in the upper middle part of the unstable rock mass sample 2;

[0151] The self-sealing water injection head 310 can inject high-pressure corrosion solution into the water injection hole 202, and uses its self-sealing function to prevent the high-pressure corrosion solution from flowing out of the hole; the self-sealing water injection head 310 is composed of an inner hollow steel tube 3101 and an outer rubber sleeve 3102 (e.g., ...). Figure 6 As shown); the outer rubber sleeve 3102 is wrapped around the outer side of the inner hollow steel tube 3101. The two ends of the outer rubber sleeve 3102 are tightly fixed to the outer side of the inner hollow steel tube 3101, forming a cavity; there is a connecting hole between the outer rubber sleeve 3102 and the inner hollow steel tube 3101, which is used to allow pressurized solution to enter the cavity, thereby making the outer rubber sleeve 3102 adhere to the inner wall of the water injection hole 202 by water pressure to form resistance and achieve a self-sealing function;

[0152] The second high-pressure water pump 312, the second inlet pipe 313, the second outlet pipe 314 and the spray gun 315 constitute a high-pressure flushing device, which is used to provide high-pressure water erosion flow to the outlet position of the weak zone 201 when the unstable rock mass sample is subjected to the tilting collapse mode test, so as to cause local scouring at the outlet position of the weak zone 201.

[0153] The second high-pressure water pump 312 is used to provide high water pressure to the spray gun 315 to erode the outlet position of the weak zone 210;

[0154] The second high-pressure water pump 312 is connected to the solution storage tank 302 through the second inlet pipe 313; the second high-pressure water pump 312 is connected to the spray gun 315 through the second outlet pipe 314.

[0155] The spray gun 315 is fixed to the reaction frame 105, with the outlet facing the outlet position of the weak zone 201.

[0156] Specifically, such as Figure 5 The schematic diagram shown is of the data acquisition device of the simulation test system for rockfall degradation and collapse under multi-field coupling of the present invention. The data acquisition device 4 includes: a digital image correlation (DIC) deformation measurement system 401, an acoustic emission (AE) measurement system 402, an ion meter 403, and a data logger 404.

[0157] The DIC deformation measurement system 401 is installed on the side wall of the corrosion chamber 301, facing the surface of the unstable rock mass sample 2, and is used to measure the surface displacement, strain distribution and image data of the collapse process of the unstable rock mass sample 2.

[0158] The acoustic emission measurement system 401 is deployed on two opposite sides of the unstable rock mass sample 2, with one system deployed diagonally on each side. Figure 5 (a) represents side A. Figure 5 (b) is side view B, used to monitor the acoustic characteristics when the weak zone 201 ruptures;

[0159] The ion meter 403 is installed at the bottom of the corrosion chamber 301 and is used to determine the types of ions and their corresponding concentrations in the solution.

[0160] The data logger 404 is used to record the monitoring data of the DIC deformation measurement system 401, the acoustic emission measurement system 402, and the ion meter 403.

[0161] The damage degree calculation device is specifically used for:

[0162] S61: Placement of acoustic emission probes: Place 4 acoustic emission probes on two opposite sides of the square sample. Select two opposite corners on each side and place one probe on each side. Place a total of 2 probes on each side, and denoted as side A and side B.

[0163] S62: Define a three-dimensional coordinate system: with the lower left corner probe of side A as the origin O(0,0,0), the x-axis is horizontally to the right along side A, the y-axis is horizontally from side A to side B, and the z-axis is vertically upward along side A.

[0164] S63: Determine the coordinates of each probe: Let the horizontal distance (x-axis direction) between two probes on the same side be L, the distance between two sides (y-axis direction) be W, and the vertical distance (z-axis direction) between two probes on the same side be H. Then the coordinates of the four probes can be defined as follows: Side A (y=0): Probe P1(0,0,0), Probe P2(L,0,H); Side B (y=W): Probe P3(L,W,0), Probe P4(0,W,H);

[0165] S64: Solving for the distance between the rupture point and the probe: Let the three-dimensional coordinates of the rupture point be S(x,y,z), and the acoustic emission signal propagates from S to the i-th probe P. ᵢ The time is t ᵢ Then the signal propagation distance d ᵢ With time t ᵢ satisfy:

[0166] (1);

[0167] In the formula, v is the speed of sound wave propagation;

[0168] S65: Calculate the time difference of each probe: Based on the arrival time difference of the signals received by the four probes, take the probe that first receives the acoustic emission signal as the time reference, denoted as t0, and calculate the time difference of the other three probes relative to the reference probe:

[0169] (2);

[0170] S66: Construct a system of three-dimensional coordinate equations: According to the spherical propagation model, the distance from the rupture point S(x,y,z) to any two probes P ᵢ P ⱼ The distance difference satisfies:

[0171] (3);

[0172] Probe P ᵢ The distance to any point is:

[0173] (4);

[0174] Substituting equation (4) into equation (3), and selecting three independent probe combinations, such as P1 and P2, P1 and P3, and P1 and P4, we obtain the three-dimensional coordinate equation system:

[0175] (5);

[0176] S67: Solving for the coordinates of the fracture point: Based on iterative fitting of multiple sets of data, the "Newton-Raphson iteration method" is used to solve formula (5) to obtain the coordinates S(x,y,z) of the fracture point; First, initialize the coordinates of the fracture point S0(x0,y0,z0), which can be taken as the geometric center coordinates of the sample, i.e. (L / 2,W / 2,H / 2); Then, linearize the nonlinear equation system at S0, construct the Jacobian matrix, and solve for the iterative correction quantities Δx, Δy, and Δz; Next, update the coordinates of the fracture point: S k+1 =S k +(Δx,Δy,Δz), and calculate the residual u=|f(S) k+1)|, where f is the difference between the left and right sides of the equation system; finally, if the residual u < the set threshold, a threshold of 10 is recommended. -4 If the value of mm is reached, the iteration converges, and the coordinates of the break point S(x,y,z) are output; otherwise, the above iteration steps are repeated until convergence.

[0177] It should be noted that the Newton-Raphson method is a second-order convergent numerical iterative method based on Taylor expansion. It constructs a function by approximating the original function with the tangent line at the iteration point, and uses the intersection of the tangent line and the coordinate axis as the new iteration point to gradually approximate the root of the nonlinear equation (system). It can also be used to solve the extrema of functions, optimization problems, and equilibrium solutions in nonlinear mechanics. It is a classic method for solving nonlinear problems in numerical analysis. The least squares method is a numerical fitting and parameter estimation method based on minimizing the sum of squared errors. By minimizing the sum of squared residuals between the observed values ​​and the calculated values ​​of the model, it determines the optimal parameters of the model to be fitted, achieving the best fit to the data, or estimating the optimal values ​​of unknown parameters from observation data containing errors. It is a fundamental mathematical method in regression analysis, data fitting, parameter identification, and other fields.

[0178] S68: Constructing the fracture surface: By continuously monitoring multiple sets of acoustic emission signals, the coordinates of multiple fracture points S1(x1,y1,z1), S2(x2,y2,z2), ..., S n (x n ,y n ,z n To construct a plane, at least three points are required, therefore at least three sets of acoustic emission signals must be obtained, meaning n must be greater than or equal to three. The least squares method is used to fit the equation of the rupture surface.

[0179] ax+by+cz+d=0 (6);

[0180] Where a, b, c, and d are fitting coefficients that minimize the sum of the squared distances from all fracture points to the plane. The plane equation is obtained through fitting, and the area s of the fracture surface in the square specimen is obtained by using the outermost fracture point on the plane as the boundary. t ;

[0181] S69: Constructing the damage model: Based on the fracture surface area and the initial area s0 of the weak zone in the sample, the damage model is obtained:

[0182] (7);

[0183] S610: Based on the damage model, the degree of damage at time t is calculated using the cumulative acoustic emission signal at time t. .

[0184] The safety factor calculation device is specifically used for:

[0185] S71: Select five external factors as independent variables, design an orthogonal experiment with five independent variables and four levels, and use Lo... 16 (4 5 An orthogonal experimental table (16 groups of experiments, including 1 blank column for error analysis) was prepared, and orthogonal experimental tests were conducted to calculate the residual shear strength test value under each combination. The five external factors included: the type and corresponding concentration of corrosive ions, osmotic pressure, vertical stress, number of wet and dry cycles and time.

[0186] It should be noted that L 16 (4 5 An orthogonal experimental table is a 4-level, 5-factor orthogonal experimental table, belonging to the classic type of four-level orthogonal table. The total number of experiments is 16, and a maximum of 5 four-level experimental factors can be arranged. It can arrange experiments in a uniform and comparable manner, and is suitable for scenarios that need to investigate the influence of multiple four-level factors on experimental indicators.

[0187] S72: Normalize the independent variables and map them uniformly to the [0,1] interval to eliminate the differences in the dimensions and value ranges of the five independent variables; among them, the normalized value of the number of wet-dry cycles is X1, the normalized value of the types of corrosive ions and their corresponding concentrations is X2, the normalized value of vertical stress is X3, the normalized value of osmotic pressure is X4, and the normalized value of time is X5.

[0188] S73: Establish a model relating five normalized values ​​to residual shear strength test values:

[0189] (8);

[0190] In the formula, This represents the residual shear strength test value; This represents the initial shear strength of the weak zone. is a natural constant, approximately equal to 2.71828; a, b, c, d, and f are the main effect weights of their respective independent variables, determined through regression fitting of experimental data. A larger weight corresponds to a greater impact of the independent variable on the dependent variable. The more significant the effect, the more significant the influence; g, h, m, and n are the interaction effect coefficients between the two factors, reflecting the influence of the synergistic effect of the independent variable on the dependent variable, such as "wet-dry cycle-chemical erosion" (X1 and X2), "permeable water pressure-time" (X4 and X5), "tangential stress-permeable water pressure" (X3 and X4), and "erosion ions-time" (X2 and X5).

[0191] S74: Based on the results of 16 orthogonal experiments, the least squares method was used to fit the model parameters, obtaining parameters a, b, c, d, f, g, h, m, and n, which were then substituted back into the relational model. The relationship model expressions between the five normalized values ​​and the residual shear strength test values ​​were obtained as follows:

[0192] (9); including:

[0193] First, data preprocessing was performed: the normalized values ​​of the independent variables X1~X5 and the measured values ​​of the dependent variables from the 16 orthogonal experiments were organized. ;

[0194] Then, perform initial fitting: substitute the data X1~X5 into the model. The least squares method is used for preliminary parameter fitting to obtain the theoretical value of the dependent variable. Compared with measured values The sum of squared errors is minimized, i.e. ;

[0195] Next, stepwise regression optimization was performed: significant interaction terms were screened using the F-test (significance level α=0.05), insignificant interaction terms were removed, the model structure was optimized, and the fitting accuracy was improved.

[0196] Finally, the accuracy was verified: the coefficient of determination (R²) and root mean square error (RMSE) were used to verify the model's fit. The requirements were R² ≥ 0.92 and RMSE ≤ 0.05 MPa, ensuring the model could accurately predict the dependent variable under different combinations of independent variables. .

[0197] S75: Based on the actual five external factors and the relational model expression, obtain the predicted value of the residual shear strength under these external factors. It should be noted that the residual shear strength test value is the measured value obtained from 16 sets of tests; after substituting the measured values ​​(dependent variable) obtained from 16 sets of tests and 5 external factors (independent variables) into formula (8) to obtain parameters a, b, c, d, f, g, h, m, n, the parameters a, b, c, d, f, g, h, m, n are then substituted back into formula (8) to obtain formula (9). At this time, the part on the left side of formula (9) becomes the predicted value of residual shear strength. ;

[0198] S76: Based on the volume and shape of the unstable rock mass and the residual shear strength under these external factors. The safety factor of the unstable rock mass is calculated using either the strength reduction method or the limit equilibrium method. .

[0199] It should be noted that the strength reduction method involves gradually reducing the material strength parameters (here referring to residual shear strength). The first method, combining finite element iterative solution with a reduction factor as the safety factor, is a numerical method for analyzing the stability of soil and rock masses without the need for a pre-slip surface. Its core advantage is its ability to automatically identify the slip surface and output the distribution of stress, deformation, and plastic zones. The second method, the limit equilibrium method, is a classic stability assessment method in geotechnical engineering. Based on the Mohr-Coulomb shear strength criterion, this method divides the potential slip body into several blocks and solves for the inter-block forces and the overall safety factor through static equilibrium (force / moment equilibrium). This method is computationally simple and has clear physical meaning, making it the mainstream method recommended by engineering specifications, and is particularly suitable for routine stability analysis of rock slopes, unstable rock masses, and rock foundations.

[0200] The security assessment device is specifically used for:

[0201] S81: Extract safety factor based on test data and damage severity indicators ;

[0202] S82: A comprehensive evaluation model is constructed using a combination of weighted fusion and threshold determination.

[0203] (10);

[0204] In the formula, ; For comprehensive evaluation index; The weight of the safety factor The weight assigned to the degree of damage;

[0205] S83: Based on the comprehensive evaluation index and in accordance with the evaluation rules, the safety status is obtained. The evaluation rules are as follows:

[0206] when At this time, it is at Level I, extremely safe, with no warning, and is in a stable state. It is characterized by slight deterioration, no risk of instability, and good long-term safety. Continuous monitoring is sufficient.

[0207] when At present, Level II is relatively safe. Blue alert, low risk, basically stable, with slight deterioration. There is no risk of instability in the short term, but long-term attention should be paid to the accumulation of deterioration.

[0208] when At that time, Level III, critical safety, yellow warning, medium risk, is a critical stable state with obvious deterioration and local minor ruptures. Extreme conditions (such as rainstorms and earthquakes) may exacerbate the risk of instability.

[0209] when At that time, it was classified as Level IV, an unstable state, with a red alert and high risk. It was an unstable state with severe deterioration, and the rupture surface had been connected or developed over a large area, posing an immediate risk of instability and collapse.

[0210] like Figure 7 As shown in the figure, this invention also provides a method for simulating the deterioration and collapse of unstable rock under multi-field coupling, which is carried out using the aforementioned simulation test system for unstable rock under multi-field coupling. The method includes the following steps:

[0211] (1) Prepare rock mass specimen 2: Select a rock mass in its natural state containing a weak zone. When simulating a sliding collapse mode, design the angle of the weak zone to be less than 90°; when simulating a tilting collapse mode or a falling collapse mode, design the angle of the weak zone to be greater than 90°; cut out a square rock mass specimen containing a weak zone according to the designed angle of the weak zone.

[0212] (2) Install flexible stress loading device 1: Use steel sections to weld a 12-sided frame that can be extended vertically as a reaction frame 105. Place the unstable rock mass sample 2 at the bottom of the frame. Arrange the hydraulic pillow 101, pad 103 and ball bearing 104 on the unstable rock mass sample 2 in sequence. Adjust the height of the reaction frame 105 so that the ball bearing 104 contacts the reaction frame 105. Connect the hydraulic pillow 101 and the high pressure oil pump 102 with a high pressure oil pipe.

[0213] (3) Install corrosion device 3: Connect solution storage tank 302, water pump 303, water pipe 304, drain pipe 305, solenoid valve 306 to corrosion tank 301 to complete the installation of dry and wet circulation device; connect first high pressure water pump 7, first inlet pipe 308, first outlet pipe 309, water pressure sensor 311 to self-sealing water injection head 310, and install self-sealing water injection head 310 to water injection hole 202 of dangerous rock mass sample 2 to complete the installation of high pressure permeation device; connect second high pressure water pump 312, second inlet pipe 313, second outlet pipe 314 to spray gun 315, and install spray gun 315 on the side of reaction frame 105 and aim it near the rock layer outlet of dangerous rock mass sample 24 to complete the installation of high pressure flushing device;

[0214] (4) Install data acquisition device: Place 4 acoustic emission probes on two opposite sides of the square sample, and place 1 probe on each of the two opposite corners of each side, for a total of 2 probes on each side, denoted as side A and side B; place the DIC deformation measurement system 401 on the side wall of the corrosion chamber 301, facing the surface of the unstable rock sample 2; place the ion meter 403 at the bottom of the corrosion chamber 301; connect the above devices to the data recorder 404 using a data cable;

[0215] (5) Scouring to form a hollow zone: When simulating the collapse mode, a high-pressure scouring device is used to scour the weak zone outlet to form a hollow zone, but the hollow zone is not connected with the weak zone; when simulating the collapse mode, a high-pressure scouring device is used to scour the weak zone outlet to form a hollow zone, and the hollow zone is connected with the weak zone.

[0216] (6) Conduct collapse simulation tests: Set up 5 external factors: vertical stress, carry out test work, and record test data;

[0217] (7) Calculate the degree of damage: Calculate the location of the fracture point in the weak zone of the rock mass based on the acoustic characteristics collected by the acoustic emission measurement system, construct the through fracture surface based on the location of the fracture point, and obtain the damage model based on the through fracture surface to further calculate the degree of damage of the dangerous rock mass under multi-field coupling.

[0218] (8) Calculate the safety factor: Based on the vertical stress when the unstable rock mass sample is unstable, obtain the residual shear strength test value of the weak zone of the rock mass under multi-field coupling, and based on the residual shear strength test value under multiple sets of external factors, obtain the relationship model between the residual shear strength test value and the external factors, and based on the relationship model and the specific external factors of the unstable rock mass, predict the residual shear strength under the specific external factors, and further obtain the safety factor based on the residual shear strength prediction value under the specific external factors, the volume and shape of the unstable rock mass;

[0219] (9) Safety assessment: Based on the safety factor and the degree of damage, an assessment model is constructed to assess the safety status of the dangerous rock mass and to conduct graded early warning.

[0220] The present invention provides a simulation test system and method for the deterioration and collapse of unstable rocks under multi-field coupling, which has at least the following advantages compared with the prior art:

[0221] 1. More realistic stress simulation: Through a flexible stress loading device including hydraulic pillows, ball bearings, etc., it can provide vertical stress loading with uneven deformation for unstable rock mass samples, which solves the stress concentration problem caused by rigid loading. It can more realistically restore the stress level of the rock mass in its natural state at a 1:1 ratio, making the test failure mechanism more in line with reality.

[0222] 2. Comprehensive coverage of failure modes: By designing weak zones at different angles and combining them with high-pressure scouring devices to form hollowed-out zones, it is possible to flexibly prepare and simulate rock mass samples with various typical collapse modes such as sliding, tilting, and falling, thus overcoming the limitation of traditional devices in simulating only one failure mode.

[0223] 3. Precise and controllable multi-field coupled environment: By integrating a corrosion device that combines dry and wet circulation, internal high-pressure infiltration and external scouring, it is possible to simulate the synergistic deterioration effect of stress field, seepage field and chemical field from both internal and external dimensions, thus realizing the simulation of the multi-field coupled environment of the entire process of "formation-deterioration-instability" of unstable rock mass.

[0224] 4. Intelligent closed-loop assessment system: By integrating multi-source data acquisition devices such as acoustic emission, pressure gauge, and ion meter, and coupling crack initiation point calculation, shear strength calculation and safety assessment devices, a complete technical chain of "multi-index synchronous monitoring → damage and strength quantification → safety status fusion assessment → risk classification and early warning" is constructed, realizing intelligent and quantitative assessment from simulation to early warning, and improving the accuracy and reliability of early warning.

[0225] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not 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 modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A simulation test system for the deterioration and collapse of unstable rocks under multi-field coupling, characterized in that, include: Flexible stress loading device, unstable rock mass sample, corrosion device, data acquisition device, damage degree calculation device, safety factor calculation device, unstable rock mass safety assessment device; The flexible stress loading device provides vertical stress to the unstable rock mass sample so that the unstable rock mass sample has the same stress level as the natural state. The flexible loading allows uneven deformation of the contact surface. The unstable rock mass sample is installed in the flexible stress loading device and is divided into stable rock mass and unstable rock mass by the weak zone. By changing the angle of the weak zone in different unstable rock mass samples, and combining it with the scouring of the weak zone outlet to form a hollowed-out zone of different degrees, it is possible to make unstable rock mass samples under sliding, tilting and falling collapse modes. By making different unstable rock mass samples, it is possible to realize the test simulation of multiple collapse modes. The corrosion device is installed below the flexible stress loading device. It provides a dry-wet cycle environment for the unstable rock mass sample from the outside, causing corrosion and deterioration on the surface of the unstable rock mass, and provides an osmotic pressure environment for the unstable rock mass sample from the inside, causing corrosion and deterioration in the weak zone inside the unstable rock mass under the action of seepage. The data acquisition device is used to record the surface displacement, acoustic characteristics and external factors of the rock mass along the weak zone. The external factors include the types and concentrations of corrosive ions, osmotic pressure, vertical stress, number of wet-dry cycles and time. The damage degree calculation device is used to calculate the location of the fracture point in the weak zone of the rock mass based on the acoustic characteristics collected by the data acquisition device, construct a through fracture surface based on the location of the fracture point, obtain a damage model based on the through fracture surface, and further calculate the damage degree of the dangerous rock mass under multi-field coupling. The safety factor calculation device is used to obtain the residual shear strength test value of the weak zone of the rock mass under multi-field coupling based on the vertical stress when the unstable rock mass sample is unstable, and to obtain the relationship model between the residual shear strength test value and the external factors based on the residual shear strength test value under multiple sets of external factors. Based on the relationship model and the specific external factors of the unstable rock mass, the device predicts the residual shear strength under the specific external factors, and further obtains the safety factor based on the residual shear strength prediction value under the specific external factors, the volume and shape of the unstable rock mass. A safety assessment device is used to construct an assessment model based on the safety factor and the degree of damage to assess the safety status of dangerous rock masses and to provide graded early warnings. The unstable rock mass sample is divided into stable rock mass and unstable rock mass by weak zone. According to the different angles of weak zone and different degrees of hollowing zone, samples with different weak zone angles and different degrees of hollowing zone are made to simulate a variety of collapse modes. The various collapse modes include sliding, toppling and falling. The side of the unstable rock mass sample has a water injection hole, which is used to provide an osmotic pressure environment for the unstable rock mass sample from the inside, and to cause corrosion and deterioration of the weak zone inside the unstable rock mass under the action of seepage. The corrosion device includes a dry-wet circulation device, a high-pressure permeation device, a high-pressure flushing device, and a corrosion solution; The dry-wet circulation device is used to provide a dry-wet circulation environment for the unstable rock mass sample from the outside, which causes corrosion and deterioration on the surface of the unstable rock mass. The high-pressure permeation device is used to provide an osmotic pressure environment for the unstable rock mass sample from the inside, thereby reducing corrosion and deterioration caused by seepage inside the unstable rock mass. The high-pressure scouring device is used to provide high-pressure water erosion flow to the weak zone outlet position when conducting the tilting and falling collapse mode tests on the unstable rock mass sample, so as to create a local erosion zone at the weak zone outlet position. The corrosive solution is a mixed solution composed of different types of corrosive ions and their corresponding concentrations.

2. The simulation test system for rockfall degradation and collapse under multi-field coupling as described in claim 1, characterized in that: The flexible stress loading device includes a hydraulic pillow, a high-pressure oil pump, pads, ball bearings, and a reaction frame; The hydraulic pillow is placed on the top surface of the unstable rock mass sample. The flexible characteristics of the hydraulic pillow are used to apply flexible pressure to the top surface, so that the top surface can undergo uneven deformation under the action of flexible pressure and the sliding action of weak zone. The reaction frame, used to provide reaction force for the hydraulic pillow, is a 12-sided steel frame welded from structural steel. A thick steel plate is arranged on the top and bottom of the reaction frame as a top plate and a bottom plate, respectively. The four side columns on the side of the 12-sided steel frame can extend and retract vertically to adjust the height of the reaction frame according to the height of the unstable rock mass sample. The pad is used to fill the gap between the hydraulic pillow and the reaction frame; The ball bearing system is used to enable the hydraulic pillow to move horizontally; The high-pressure oil pump is used to provide high-pressure hydraulic oil to the hydraulic pillow, and an oil pressure gauge is installed at the oil outlet of the high-pressure oil pump to monitor the flexible pressure.

3. The simulation test system for rockfall degradation and collapse under multi-field coupling as described in claim 2, characterized in that: The dry-wet circulation device includes: a corrosion tank, a solution storage tank, a water pump, a water pumping pipe, a drain pipe, and a solenoid valve; The water pump is located inside the solution storage tank and is connected to the corrosion tank via the water pumping pipe; The solution storage tank is used to store the corrosive solution and is connected to the corrosion tank through the drain pipe. The drain pipe is equipped with the solenoid valve to control the opening and closing state of the drain pipe. The water pump and the solenoid valve work alternately to provide a dry-wet cycle corrosion environment for the corrosion chamber; The high-pressure permeation device includes a first high-pressure water pump, a first inlet pipe, a first outlet pipe, a self-sealing water injection head, and a water pressure sensor. The first high-pressure water pump is connected to the solution storage tank through the first water inlet pipe; The first high-pressure water pump is connected to the self-sealing water injection head through the first water outlet pipe; The self-sealing water injection head is installed in the water injection hole of the unstable rock mass sample; The self-sealing water injection head can inject high-pressure corrosion solution into the water injection hole, and the self-sealing function prevents the high-pressure corrosion solution from flowing out of the hole along the water injection hole. The self-sealing water injection head includes an inner hollow steel pipe and an outer rubber sleeve. The outer rubber sleeve wraps around the outside of the inner hollow steel pipe to form a cavity. The outer rubber sleeve and the inner hollow steel pipe have a communication hole for allowing the pressurized corrosive solution to enter the cavity. The outer rubber sleeve then uses water pressure to adhere to the inner wall of the injection hole to form resistance, thereby achieving a self-sealing function. The high-pressure corrosion solution can penetrate into the unstable rock mass sample; The first high-pressure water pump is used to provide osmotic pressure to the interior of the unstable rock mass sample. The first high-pressure water pump is equipped with a water pressure sensor at the outlet position. The water pressure sensor is used to record the osmotic pressure provided by the first high-pressure water pump to the interior of the unstable rock mass sample. The high-pressure flushing device includes a second high-pressure water pump, a second inlet pipe, a second outlet pipe, and a spray gun. The second high-pressure water pump is connected to the solution storage tank through the second water inlet pipe; The second high-pressure water pump is connected to the spray gun through the second outlet pipe; The spray gun is fixed to the reaction frame, and the outlet is facing the weak zone outlet position; The second high-pressure water pump is used to provide high water pressure to the spray gun to erode the weak zone outlet position, thereby forming a hollowed-out area.

4. The simulation test system for rockfall degradation and collapse under multi-field coupling as described in claim 3, characterized in that: The data acquisition device includes a DIC deformation measurement system, an acoustic emission measurement system, an ion meter, and a data logger; The DIC deformation measurement system is installed on the side wall of the corrosion chamber, facing the surface of the unstable rock mass sample, and is used to measure the surface displacement, strain distribution and image data of the collapse process of the unstable rock mass sample. The acoustic emission measurement system is deployed on two opposite sides of the unstable rock mass sample, with one system deployed diagonally on each side, to monitor the acoustic characteristics when the weak zone ruptures. The ion meter is installed at the bottom of the corrosion chamber and is used to determine the types of ions and their corresponding concentrations in the solution. The data logger is used to record the monitoring data of the DIC deformation measurement system, the acoustic emission measurement system and the ion meter, as well as the osmotic pressure, the vertical stress, the number of wet-dry cycles and the time during the test.

5. The simulation test system for rockfall degradation and collapse under multi-field coupling as described in claim 4, characterized in that: The damage degree calculation device is specifically used for: S61: Placement of acoustic emission probes: Place 4 acoustic emission probes on two opposite sides of the square sample. Select two opposite corners on each side and place one probe on each side. Place a total of 2 probes on each side, and denoted as side A and side B. S62: Define a three-dimensional coordinate system: with the lower left corner probe of side A as the origin O(0,0,0), the x-axis is horizontally to the right along side A, the y-axis is horizontally from side A to side B, and the z-axis is vertically upward along side A. S63: Determine the coordinates of each probe: Let the horizontal distance between two probes on the same side be L, the distance between two sides be W, and the vertical distance between two probes on the same side be H. Then the coordinates of the four probes can be defined as follows: Side A: Probe P1 (0,0,0), Probe P2 (L,0,H); Side B: Probe P3 (L,W,0), Probe P4 (0,W,H); S64: Solving for the distance between the rupture point and the probe: Let the three-dimensional coordinates of the rupture point be S(x,y,z), and the acoustic emission signal propagates from S to the i-th probe P. ᵢ The time is t ᵢ Then the signal propagation distance d ᵢ With time t ᵢ satisfy: (1)； In the formula, v is the speed of sound wave propagation; S65: Calculate the time difference of each probe: Based on the arrival time difference of the signals received by the four probes, take the probe that first receives the acoustic emission signal as the time reference, denoted as t0, and calculate the time difference of the other three probes relative to the reference probe: (2)； S66: Construct a three-dimensional coordinate equation system: from the rupture point S(x,y,z) to any two probes P ᵢ P ⱼ The distance difference satisfies: (3)； Probe P ᵢ The distance to any point is: (4)； Substituting equation (4) into equation (3), and selecting three independent probe combinations, such as P1 and P2, P1 and P3, and P1 and P4, we obtain the three-dimensional coordinate equation system: (5)； S67: Solve for the coordinates of the rupture point: Based on the iterative fitting of multiple sets of data, the "Newton-Raphson iteration method" is used to solve formula (5) to obtain the coordinates S(x,y,z) of the rupture point; S68: Constructing the fracture surface: By continuously monitoring multiple sets of acoustic emission signals, the coordinates of multiple fracture points S1(x1,y1,z1), S2(x2,y2,z2), ..., S n (x n ,y n ,z n ), where n is a natural number greater than or equal to 3, and the least squares method is used to fit the equation of the rupture surface: ax+by+cz+d=0 (6); Where a, b, c, and d are fitting coefficients that minimize the sum of the squared distances from all fracture points to the fracture surface. The plane equation is obtained through fitting, and the area s of the fracture surface in the square specimen is obtained by using the outermost fracture point on the plane as the boundary. t ; S69: Constructing the damage model: Based on the fracture surface area and the initial area s0 of the weak zone in the sample, the damage model is obtained: (7)； S610: Based on the damage model, the degree of damage at time t is calculated using the cumulative acoustic emission signal at time t. .

6. The simulation test system for rockfall degradation and collapse under multi-field coupling as described in claim 1, characterized in that, The safety factor calculation device is specifically used for: S71: Select five external factors as independent variables, design an orthogonal experiment with five independent variables and four levels, and use Lo... 16 (4 5 Orthogonal experimental tables were used, and orthogonal experimental tests were conducted to calculate the residual shear strength test value for each combination. The five external factors included: the type and corresponding concentration of corrosive ions, osmotic pressure, vertical stress, number of wet-dry cycles and time. The residual shear strength test value was calculated based on the vertical stress on the top surface of the unstable rock mass, the area of ​​the top surface, the angle of the weak zone, and the area of ​​the weak zone when the unstable rock mass underwent sliding failure. S72: Normalize the independent variables and map them uniformly to the [0,1] interval to eliminate the differences in the dimensions and value ranges of the five independent variables; among them, the normalized value of the number of wet-dry cycles is X1, the normalized value of the types of corrosive ions and their corresponding concentrations is X2, the normalized value of vertical stress is X3, the normalized value of osmotic pressure is X4, and the normalized value of time is X5. S73: Establish a model relating five normalized values ​​to residual shear strength test values: (8)； In the formula, This represents the residual shear strength test value; This represents the initial shear strength of the weak zone. is a natural constant; a, b, c, d, and f are the main effect weights of their respective independent variables, determined through regression fitting of experimental data. The larger the weight, the greater the impact of the independent variable on the dependent variable. The more significant the effect, the greater the impact; g, h, m, and n are the interaction coefficients between the two factors, reflecting the influence of the synergistic effect of the independent variables on the dependent variable; S74: Based on the results of 16 orthogonal experiments, the least squares method was used to fit the model parameters, obtaining parameters a, b, c, d, f, g, h, m, and n, which were then substituted back into the relational model. Five normalized values ​​and predicted residual shear strength were obtained. Relational model expression: (9)； S75: Based on the five external factors of the actual rock mass and the relational model expression (9), the predicted value of the residual shear strength under these external factors is obtained. ; S76: Predicted residual shear strength based on the volume and shape of the unstable rock mass and the external factors. The safety factor of the unstable rock mass is calculated using either the strength reduction method or the limit equilibrium method. .

7. The simulation test system for rockfall degradation and collapse under multi-field coupling as described in claim 1, characterized in that, The security assessment device is specifically used for: S81: Extract safety factor based on test data and damage severity indicators ; S82: A comprehensive evaluation model is constructed using a combination of weighted fusion and threshold determination. (10)； In the formula, ; For comprehensive evaluation index; The weight of the safety factor The weight assigned to the degree of damage; S83: Based on the comprehensive evaluation index and in accordance with the evaluation rules, the safety status is obtained. The evaluation rules are as follows: when At this time, it is at Level I, extremely safe, with no warning, and is in a stable state. It is characterized by slight deterioration, no risk of instability, and good long-term safety. Continuous monitoring is sufficient. when At present, Level II is relatively safe. Blue alert, low risk, basically stable, with slight deterioration. There is no risk of instability in the short term, but long-term attention should be paid to the accumulation of deterioration. when At that time, Level III, critical safety, yellow warning, medium risk, is a critical stable state with obvious deterioration, local minor cracks, and may exacerbate the risk of instability under extreme working conditions; when At that time, it was classified as Level IV, an unstable state, with a red alert and high risk. It was an unstable state with severe deterioration, and the rupture surface had been connected or developed over a large area, posing an immediate risk of instability and collapse.

8. A method for simulating the deterioration and collapse of unstable rocks under multi-field coupling, characterized in that, The method utilizes the multi-field coupling simulation test system for rockfall degradation and collapse as described in any one of claims 1 to 7, and includes the following steps: (1) Prepare rock mass specimens: Select rock mass in its natural state containing a weak zone. When simulating a sliding collapse mode, design the angle of the weak zone to be less than 90°. When simulating a toppling collapse mode or a falling collapse mode, design the angle of the weak zone to be equal to or greater than 90°. Cut out a square rock mass specimen containing a weak zone according to the designed angle of the weak zone. (2) Install flexible stress loading device: Use steel profiles to weld a 12-sided frame that can be extended vertically. Place a thick steel plate on the top and bottom of the reaction frame as the top plate and bottom plate respectively. Place the unstable rock mass sample on the bottom plate. Place the hydraulic pillow, pad block and ball bearing row on the unstable rock mass sample in sequence. Adjust the height of the frame so that the ball bearing row contacts the top plate. Connect the hydraulic pillow and high pressure oil pump with high pressure oil pipe. (3) Install the corrosion device: Connect the solution storage tank, water pump, water pipe, drain pipe, and solenoid valve to the corrosion tank to complete the installation of the dry-wet cycle device; connect the first high-pressure water pump, the first water inlet pipe, the first water outlet pipe, and the water pressure sensor to the self-sealing water injection head, and install the self-sealing water injection head to the water injection hole of the unstable rock mass sample to complete the installation of the high-pressure permeation device; connect the second high-pressure water pump, the second water inlet pipe, and the second water outlet pipe to the spray gun, and install the spray gun on the side of the reaction frame and aim it near the rock layer outlet of the unstable rock mass sample to complete the installation of the high-pressure flushing device; (4) Install data acquisition device: Place 4 acoustic emission probes on two opposite sides of the square sample, and place 1 probe on each of the two opposite corners of each side, for a total of 2 probes on each side, denoted as side A and side B; place the DIC deformation measurement system on the side wall of the corrosion chamber, facing the surface of the unstable rock sample; place the ion meter at the bottom of the corrosion chamber; connect the above devices to the data logger using a data cable; (5) Scouring to form a hollow zone: When simulating the collapse mode, a high-pressure scouring device is used to scour the weak zone outlet to form a hollow zone, but the hollow zone is not connected with the weak zone; when simulating the collapse mode, a high-pressure scouring device is used to scour the weak zone outlet to form a hollow zone, and the hollow zone is connected with the weak zone. (6) Conduct collapse simulation test: Set 5 external factors: the type and corresponding concentration of corrosive ions, osmotic pressure, vertical stress, number of wet and dry cycles and time, conduct test work, and record the residual shear strength test data; (7) Calculate the damage degree of the dangerous rock mass under multi-field coupling: Calculate the location of the fracture point in the weak zone of the rock mass based on the acoustic characteristics collected by the acoustic emission measurement system, construct the through fracture surface based on the location of the fracture point, and obtain the damage model based on the through fracture surface to further calculate the damage degree of the dangerous rock mass under multi-field coupling. (8) Calculate the safety factor: Based on the vertical stress when the unstable rock mass sample is unstable, obtain the residual shear strength test value of the weak zone of the rock mass under multi-field coupling, and based on the residual shear strength test value under multiple sets of external factors, obtain the relationship model between the residual shear strength test value and the external factors, and based on the relationship model and the specific external factors of the unstable rock mass, predict the residual shear strength under the specific external factors, and further obtain the safety factor based on the residual shear strength prediction value under the specific external factors, the volume and shape of the unstable rock mass; (9) Safety assessment: Based on the safety factor and the degree of damage, an assessment model is constructed to assess the safety status of the dangerous rock mass and to conduct graded early warning.

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