Device and method for researching water and mud bursting mechanism of fault argillization zone

Abstract

The invention discloses a device and a method for researching a water and mud bursting mechanism of a fault argillization zone, and belongs to the technical field of underground engineering, and the device adopts a modular design and mainly comprises a loading assembly used for applying axial stress; the sleeve assembly is used for accommodating a sample and providing confining pressure; the abutting assembly is used for transmitting a load; and the water pressure assembly is used for applying permeation water pressure and realizing uniform water supply. According to the method, by integrating the modules, the fault argillization zone occurrence environment under the high ground stress and high water pressure coupling condition can be accurately simulated, seepage path synchronous observation from microcosmic to macroscopic is achieved, and a multivariable orthogonal test can be carried out. The device has the advantages that the three technical problems of high ground stress-high water pressure coupling simulation, cross-scale seepage observation and efficient test are solved, and a special experiment platform and method are provided for deeply researching a fault argillization seepage failure mechanism and formulating engineering prevention and control measures.

Description

Technical Field

[0001] This invention relates to the field of underground engineering, and in particular to an apparatus and method for studying the mechanism of water inrush and mud inrush in fault mud zones. Background Technology

[0002] With the rapid development of infrastructure, an increasing number of deep-buried tunnels and underground engineering projects need to traverse complex geological environments such as water-rich fault zones and mudstone zones, especially in the mountainous areas of central and western China and regions with complex hydrogeological conditions. Deep-buried tunnel construction often faces unique conditions of "high ground pressure, high water pressure, and strong disturbance," which increases the risk of geological disasters such as water inrush, mudslides, collapses, and large deformations. This not only poses a potential threat to project safety but may also cause economic losses and construction safety hazards.

[0003] Due to the high self-weight stress and pore water pressure levels of the surrounding rock in deeply buried tunnels, the stress-seepage coupling effect of the surrounding rock cannot be ignored during construction. Deeply buried tunnels are prone to water inrush and mud inrush when crossing water-rich fault mudflats, which has become one of the most common and dangerous hidden dangers in tunnels and underground engineering. Therefore, studying the mechanical and hydraulic properties of the surrounding rock in deeply buried tunnels crossing water-rich fault mudflats, and exploring its stress-seepage coupling behavior under high ground stress and high water head conditions, is of great significance in preventing water inrush and mud inrush during tunnel construction.

[0004] The water and mud inrush disaster following seepage failure in a tunnel fault fracture zone is a complex system involving multiple scales and fields, encompassing hydrogeology, fluid dynamics, soil mechanics, rock mechanics, and other disciplines. It is influenced by various factors, including geostress conditions, the properties of the filling medium, groundwater, and construction methods. During construction, the combined effects of excavation disturbance and high seepage pressure cause the migration and loss of particles from the filling medium within the fault fracture zone, leading to a change in the internal equilibrium state and a dynamic instability process in which the mud-water mixture moves towards the tunnel's free face. The mechanism of water and mud inrush disasters is complex, closely related to geological structure, groundwater dynamics, and construction disturbance. When tunnel excavation exposes the fault fracture zone, the groundwater seepage field changes significantly. The groundwater level on the footwall side of the fault gradually decreases due to tunnel drainage, creating a large water level difference with the footwall side. This water level difference leads to a rapid change in groundwater dynamics, prompting groundwater to migrate rapidly along the fault zone and fracture network into the tunnel excavation space. Meanwhile, the triangular wedge-shaped structure above the tunnel collapsed under stress release, further exacerbating the deformation and damage of the clay interlayer within the fault zone. Under high groundwater pressure and seepage, the clay interlayer gradually became saturated, forming supersaturated soil with significantly reduced mechanical properties. Ultimately, under gravity, it surged into the tunnel as a debris flow, triggering water inrush and mudslide disasters. This process not only causes instability of the surrounding rock and damage to the support structure but may also alter the recharge and discharge conditions of regional groundwater, leading to secondary disasters such as surface subsidence and collapse, seriously threatening construction safety and the ecological environment. Summary of the Invention

[0005] This invention provides an apparatus and method for studying the mechanism of water inrush and mud inrush in fault mud zones. The purpose is to provide an apparatus for studying water inrush and mud inrush in fault mud zones, and to simulate the entire process of seepage failure, instability and mud inrush at the tunnel face when encountering mud zones during the construction of deep-buried tunnels.

[0006] To achieve the above objectives, embodiments of the present invention provide an apparatus for studying the mechanism of water inrush and mud inrush in fault muddy zones, comprising:

[0007] The loading component includes a reaction plate and a loading unit disposed on the reaction plate, wherein the movable end of the loading unit is provided with a top rod;

[0008] A sleeve assembly includes a front sleeve and a rear sleeve communicating with the front sleeve, wherein the loading component is disposed on the front side of the front sleeve;

[0009] A clamping assembly is disposed at the front end of the front cylinder. The clamping assembly includes a retaining ring and a piston disposed in the inner ring of the retaining ring and having open ends. An inner plug is disposed inside the piston. The piston and the inner plug form a limiting structure at the rear end of the piston. The push rod is detachably connected to the inner plug.

[0010] A water pressure assembly is located at the rear end of the rear cylinder. The water pressure assembly consists of a pressure plate, a water inlet plate, and a permeable plate from back to front. The pressure plate is fixed at the rear end of the rear cylinder and has a central hole connected to the water supply assembly. A water cavity is formed between the water inlet plate and the pressure plate. The water inlet plate has several water inlet holes. The permeable plate is in contact with the surface of the water inlet plate.

[0011] Preferably, a locking member is provided on the side of the reaction plate facing the sleeve assembly. The locking member is a three-quarter ring and is concentrically arranged with the reaction plate. The locking member is used to fix the loading unit.

[0012] Preferably, the front cylinder is provided with a first flange at its front end, the first flange is provided with a first flange hole, and the reaction plate and the retaining ring are respectively provided with a reaction hole and a through hole;

[0013] The loading assembly also includes a tie rod, which is sequentially inserted through the first flange hole, the through hole and the reaction hole. The tie rod is provided with a first front nut and a first rear nut on the front and rear sides of the reaction plate, respectively, and a second front nut and a second rear nut on the front and rear sides of the first flange, respectively.

[0014] A spring sheet is provided between the first rear nut and the reaction plate, and between the second front nut and the retaining ring; a gasket is provided between the first front nut and the reaction plate, and between the second rear nut and the first flange.

[0015] Several of the aforementioned tie rods are arranged in a centrally symmetrical manner about the center of the reaction plate.

[0016] Preferably, the rear end of the push rod is provided with a rearwardly protruding connecting part, which is screwed to the inner plug.

[0017] Preferably, the water inlet plate has a protrusion on the side facing the pressure plate, and the protrusion abuts against the pressure plate to form the water cavity.

[0018] On the other hand, this application also provides a method using the aforementioned apparatus for studying the mechanism of water inrush and mud inrush in fault muddy zones, comprising:

[0019] S10. Assemble the sleeve assembly and hydraulic assembly;

[0020] S20. Fill the sleeve assembly with soil, compact the soil and smooth the front end of the soil;

[0021] S30. Assemble the clamping component and the loading component, and use the loading component to press the clamping component against the soil. Observe the reading of the first pressure sensor. When the reading of the first pressure sensor reaches the preset pressure, close the loading component and fix the clamping component.

[0022] S40. Keep the piston in contact with the soil, remove the inner plug, and obtain the basic data of the pressure stabilization stage. The basic data includes the porosity development of each soil section along the axial direction of the sleeve assembly.

[0023] The water supply unit is activated. The water supply unit is equipped with a flow meter and a second pressure sensor. The water supply unit gradually increases the water pressure according to the preset water pressure increase, and periodically acquires and records the porosity development of each soil section as dynamic data.

[0024] After observing the phenomenon of water inrush and mud bursting, water injection was stopped, and the porosity development of each soil section was obtained and recorded as failure data.

[0025] S50. By combining basic data, dynamic data, and damage data, a complete path diagram of the "pore-fracture-pipe" transformation is constructed to obtain the evolution rate of the soil's internal structure at different stages, and then the threshold of the critical permeability gradient is determined.

[0026] Preferably, in step S40, when the flow meter reading changes abruptly, the porosity development of each soil section is immediately acquired and recorded as dynamic data.

[0027] Preferably, in step S40, ground-penetrating radar is used to scan each soil section and the front end of the soil to obtain information on pore development.

[0028] Preferably, in step S40, a high-definition camera is installed at the piston to obtain an image of the front face of the soil.

[0029] Preferably, in step S50, a complete path diagram of the transformation from "pore-crack-pipe" is constructed by comparing the initial data, dynamic data and failure data of the same soil section at the same time node.

[0030] The above-described solution of the present invention has the following beneficial effects:

[0031] This invention, through comprehensive innovation in modular structure, precise parameters, multi-scale monitoring, and intelligent analysis, innovatively simulates the entire process of seepage failure in muddy zones under deep-buried tunnel conditions (confining pressure 15 MPa, water pressure 10 MPa), solving three major technical challenges: "coupled simulation of high ground stress and high water pressure," "synchronous observation of micro- and macro-level seepage paths," and "efficient implementation of multivariate orthogonal experiments." It provides a dedicated device and experimental method for the study of mudslide mechanisms and engineering prevention in fault muddy zones.

[0032] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0033] Figure 1 This is a sectional view of the device;

[0034] Figure 2 This is a front view of the reaction plate;

[0035] Figure 3 It is a cross-sectional view of the clamping assembly and the push rod;

[0036] Figure 4 This is a front view of the water inlet tray;

[0037] Figure 5 This is a side view of the water inlet tray.

[0038] [Explanation of Labels in the Attached Image]

[0039] 10-Loading component, 11-Reaction plate, 12-Loading unit, 13-Push rod, 14-Clamping component,

[0040] 20-Sleeve assembly, 21-Front sleeve, 22-Rear sleeve, 23-First flange, 24-Tie rod, 25-First front nut, 26-First rear nut, 27-Second front nut, 28-Second rear nut, 29-Spring leaf,

[0041] 30-Clamping assembly, 31-Retaining ring, 32-Piston, 33-Inner plug, 34-Limiting structure,

[0042] 40-Water pressure component, 41-Pressure plate, 42-Inlet plate, 43-Permeable plate, 44-Protrusion. Detailed Implementation

[0043] To make the technical problems, technical solutions and advantages of the present invention clearer, a detailed description will be given below in conjunction with the accompanying drawings and specific embodiments.

[0044] like Figures 1-5As shown, an embodiment of the present invention provides an apparatus for studying the mechanism of water inrush and mud inrush in fault muddy zones, including a loading assembly 10, a sleeve assembly 20, a clamping assembly 30, and a hydraulic pressure assembly 40. The loading assembly 10 includes a reaction plate 11 and a loading unit 12 disposed on the reaction plate 11. The loading unit 12 has a movable end and a fixed end, and the force is applied by the extension and retraction of the movable end. A push rod 13 is disposed at the movable end of the loading unit 12. The push rod 13 is detachably connected to or fixedly connected to the movable end. The aforementioned sleeve assembly 20 includes a front sleeve 21 located at the front end and a rear sleeve 22 located at the rear end of the front sleeve 21. The front sleeve 21 and the rear sleeve 22 are coaxially connected end-to-end, and the loading assembly 10 is disposed on the front side of the front sleeve 21. The clamping assembly 30 is disposed between the loading assembly 10 and the sleeve assembly 20. The clamping assembly 30 includes a retaining ring 31, which has an inner ring and an outer ring. A piston 32 is fixed in the inner ring of the retaining ring 31. The piston 32 is a cylindrical ring with open ends. An inner plug 33 is disposed inside the piston 32. A limiting structure 34 is formed at the rear end of the piston 32 to limit the inner plug 33. When the inner plug 33 is in the limiting structure 34, the rear end of the inner plug 33 is flush with the rear end of the piston 32. The limiting structure 34 can also transmit the force on the inner plug 33 to the piston 32.

[0045] Preferably, both the front cylinder 21 and the rear cylinder 22 are made of polyetheretherketone (PEEK) material.

[0046] Preferably, the inner wall of the rear end of the piston 32 forms an annular convex ring portion towards the center of the piston 32, and the outer wall of the rear end of the inner plug 33 is recessed towards the center of the inner plug 33 to form a recessed portion that cooperates with the convex ring portion. The recessed portion and the convex ring portion together form a limiting structure 34.

[0047] The water pressure assembly 40 is located at the rear end of the rear cylinder 22. The water pressure assembly 40 includes, from rear to front, a pressure plate 41, a water inlet plate 42, and a permeable plate 43. The pressure plate 41 is fixed at the rear end of the rear cylinder 22. The pressure plate 41 has a central hole for connecting to the water supply assembly. The water supply assembly fills the sleeve assembly 20 with water at a preset flow rate and pressure. A water cavity is formed between the water inlet plate 42 and the pressure plate 41. The water inlet plate 42 has several water inlet holes. The permeable plate 43 is in contact with the surface of the water inlet plate 42.

[0048] In this application, the sleeve assembly 20 is used to contain the compacted soil, the water pressure assembly 40 is used on one side of the soil and forms a high-pressure water environment to create different pore water pressures, and the clamping assembly 30 is used to apply a loading force to the soil to create different confining pressures, thereby simulating the special conditions of high ground pressure and high water pressure. At the same time, during the experiment, the piston 32 and the inner plug 33 in the clamping assembly 30 directly abut against the front end face of the soil to form a stable confining pressure. After stabilizing the pressure for a period of time, the inner plug 33 is removed and the space in the piston 32 that contains the inner plug 33 is used to simulate the working face exposure condition. By injecting water, the situation of water inrush and mud inrush at the working face is observed.

[0049] This application focuses on the phenomenon of water inrush and mud bursting caused by the combined effects of high stress and water pressure when tunnels pass through muddy zones. It conducts in-depth research on the critical permeability gradient of muddy zones under high ground stress and high water head conditions. This includes constructing a research system considering the permeability law of reshaped muddy materials under deep burial conditions (confining pressure above 15 MPa and water pressure above 10 MPa). By controlling key parameters such as confining pressure and pore water pressure, the time-varying characteristics of muddy material permeability under different stress-water pressure combinations are analyzed.

[0050] A research system was constructed to study the permeability of reconstituted sludge under deep burial conditions (confining pressure above 15 MPa and water pressure above 10 MPa). By controlling key parameters such as confining pressure and pore water pressure, the time-varying permeability characteristics of sludge under different stress-water pressure combinations were analyzed. A multivariate orthogonal experimental scheme was designed to explore the critical permeability gradient threshold of reconstituted sludge under different combinations of confining pressure, water pressure, and initial density. Simultaneously, combining real-time monitoring and ground-penetrating radar non-destructive testing technology, the failure modes at the working face and the internal crack propagation modes during seepage failure were identified. A cross-scale characterization method for reconstituted sludge from micropores to macroscopic seepage channels was constructed, elucidating the "pore-fracture-channel" transformation mechanism of seepage path formation.

[0051] The aforementioned device also includes a detection component, which includes a first pressure sensor for measuring the loading force applied by the loading component 10. The detection component also includes a second pressure sensor and a flow meter for measuring the water pressure and flow velocity of the water supply component. The detection component further includes a high-definition camera for observing the front face of the soil (i.e., the simulated working face). The detection component also includes ground-penetrating radar (GPR), which records the porosity development of the soil cross-section along the axial direction of the casing component, such as water inrush conditions and failure modes. Preferably, each detection component is also connected to a kinetic analyzer so that the kinetic analyzer records the changes in the readings or images of each sensor.

[0052] In this application, a locking member 14 is provided on the side of the reaction plate 11 facing the sleeve assembly 20. The locking member 14 is a three-quarter ring, and its axial direction is consistent with the thickness direction of the reaction plate 11. The locking member 14 is coaxially fixed together with the reaction plate 11. The loading unit 12 is engaged in the locking member 14 through the notch, thereby ensuring stability during the pressurization process.

[0053] In this application, the loading unit 12 is an FCY extended hydraulic jack, which is used with a CP-800A manual pump to achieve pressure stabilization and automatic pressure relief; a first pressure sensor is installed at the oil outlet of the CP-800A manual pump for detection.

[0054] A first flange 23 with a first flange hole is provided at the front end of the front cylinder 21. The outer diameter of the retaining ring 31, the diameter of the reaction plate 11, and the diameter of the first flange 23 are the same. Understandably, the outer diameter of the retaining ring 31 is larger than the inner diameter of the front cylinder 21. When the loading assembly 10 acts on the retaining ring 31, the retaining ring 31 abuts against the first flange 23. A reaction hole is provided on the reaction plate 11, and a through hole is provided on the retaining ring 31. The number of the first flange hole, the reaction hole, and the through hole are the same.

[0055] The loading assembly 10 also includes a tie rod 24, which is sequentially inserted through the first flange hole, the through hole and the reaction hole. The tie rod 24 is provided with a first front nut 25 and a first rear nut 26 on the front and rear sides of the reaction plate 11, respectively, and a second front nut 27 and a second rear nut 28 on the front and rear sides of the first flange 23, respectively.

[0056] Specifically, the tie rod 24 has a first end and a second end, with the first end near the reaction plate 11 and the second end near the first flange 23. The first end passes through the reaction plate 11, and a first front nut 25 and a first rear nut 26 are screwed onto both sides of the reaction plate 11, with the first front nut 25 located at the front end of the reaction plate 11 and the first rear nut 26 located at the rear end of the reaction plate 11. Similarly, the second end passes through the retaining ring 31 and the first flange 23, and a second front nut 27 and a second rear nut 28 are screwed onto the front and rear ends of the retaining ring 31, respectively. The second front nut 27 is located at the front end of the retaining ring 31, and the second rear nut 28 is located at the rear end of the first flange 23.

[0057] Furthermore, spring plates 29 are provided between the first rear nut 26 and the reaction plate 11, and between the second front nut 27 and the retaining ring 31. Gaskets are provided between the first front nut 25 and the reaction plate 11, and between the second rear nut 28 and the first flange 23. The tie rod 24 passes through the spring plates 29 and the gaskets respectively. The spring plates 29 are used to absorb the instantaneous impact generated by the loading assembly 10 during the pressurization process, so as to avoid the interference of stress fluctuations on the experimental results.

[0058] The number of tie rods 24 is the same as the number of first flange holes, and several tie rods 24 are arranged in a centrally symmetrical manner about the center of the reaction plate 11.

[0059] A rearwardly protruding connecting part is provided at the rear end of the push rod 13. The connecting part has external threads and is screwed to the inner plug 33.

[0060] The water inlet plate 42 has a protrusion 44 on the side facing the pressure plate 41. Several protrusions 44 are spaced apart to form a channel for dispersing water flow. The protrusions 44 abut against the pressure plate 41 to form a water cavity between them.

[0061] In this embodiment, the water inlet holes and the protrusions 44 are alternately arranged. The permeable plate 43 is attached to the side of the water inlet plate 42 away from the protrusions 44. The permeable plate 43 is a geotechnical test permeable plate 43, which has a certain strength and permeability coefficient to ensure the uniformity and stability of the water flow.

[0062] The water supply assembly creates a stable water pressure within the water chamber, and this pressure is applied to the soil after passing through the inlet and permeable plate 43. The water supply assembly is an HS-3000B type pressure pump.

[0063] In this application, a second flange is provided at the rear end of the rear cylinder 22, and the pressure plate 41 is fixedly connected to the second flange to fix the pressure plate 41. The connection method between the second flange and the pressure plate 41 can refer to the connection method between the first flange 23 and the retaining ring 31.

[0064] Preferably, the rear end of the front cylinder 21 and the front end of the rear cylinder 22 are also connected by flanges.

[0065] The advantages of this application are:

[0066] First, the front end of the push rod 13 is detachably connected to the clamping assembly 30, while the inner plug 33 and piston 32 can be embedded and assembled, enabling rapid switching between pressurization and stabilization modes and water injection modes. In pressurization and stabilization mode, the inner plug 33 is embedded in the piston 32, and the clamping assembly 30 is pressurized by the loading assembly 10 to ensure uniform stress on the soil and stable pressurization. In water injection mode, the inner plug 33 is removed, and the piston 32, fixed by the first flange 23 and the retaining ring 31, maintains the confining pressure of the soil. The piston 32 acts on the front face of the soil, simulating the tunnel face during excavation. Removing the inner plug 33 also provides installation space for the high-definition camera.

[0067] Secondly, a limiting structure 34 is formed between the inner plug 33 and the piston 32, which effectively transmits the loading force on the inner plug 33 to the piston 32, ensuring stable contact between the piston 32 and the inner plug 33 during pressurization, and avoiding stress concentration that could cause deformation of the clamping assembly 30.

[0068] Third, multiple tie rods 24, together with adjustable limit nuts at both ends, can dynamically adjust the horizontal distance between the reaction plate 11 and the retaining ring 31 under the action of the washer and spring plate 29, so as to accurately control the precision of the confining pressure application. The spring plate 29 effectively absorbs the instantaneous impact during the pressurization process and avoids the interference of stress fluctuations on the experimental results.

[0069] Fourth, a water cavity is formed between the water inlet plate 42 and the pressure plate 41, and a protrusion 44 is formed on the water inlet plate 42. The water flow is divided through the water cavity and the water inlet hole to achieve uniform permeation under high water pressure of 10MPa, avoid the local scouring error caused by concentrated water flow in traditional devices, and ensure the accuracy of permeability coefficient measurement.

[0070] Fifth, the distribution of water-bearing pores in the soil is scanned by ground-penetrating radar, and combined with the failure modes of the working face recorded by high-definition cameras and the real-time data obtained by dynamic instruments, a complete path map of the transformation of "pore-fracture-channel" is constructed.

[0071] This application also provides an experimental method using the aforementioned apparatus for studying the mechanism of water inrush and mud inrush in fault muddy zones, comprising the following steps:

[0072] S10. Assemble the sleeve assembly 20 and the hydraulic assembly 40.

[0073] In this step, the front cylinder 21 and the rear cylinder 22 are connected, and the permeable plate 43, the water inlet plate 42 and the pressure plate 41 are installed sequentially at the rear end of the rear cylinder 22; the water supply component is connected to the pressure plate 41.

[0074] S20. Fill the sleeve with soil, compact the soil, and smooth the front end of the soil.

[0075] In this step, the prepared soil is added to the sleeve assembly 20 in several batches according to the experimental requirements, with each batch not exceeding half the volume of the sleeve assembly 20. The soil is then evenly distributed within the sleeve assembly 20. After adding the soil sample, it is compacted using a tamping tool to ensure uniform density. After compaction, the front surface of the soil sample is smoothed.

[0076] S30. Assemble the clamping component 30 and the loading component 10, and use the loading component 10 to press the clamping component 30 against the soil. Observe the reading of the first pressure sensor. When the reading of the first pressure sensor reaches the preset pressure, close the loading component 10.

[0077] In this step, the loading unit 12 is fixed to the reaction plate 11, the inner plug 33 is embedded in the piston 32, and the piston 32 is connected to the push rod 13. The pull rod 24 is passed through the reaction plate 11, the retaining ring 31, and the first flange 23. At the end of the pull rod 24 near the reaction plate 11, a first front nut 25 and a first rear nut 26 are screwed to both sides of the reaction plate 11, respectively. At the end of the pull rod 24 near the first flange 23, a second front nut 27 is screwed to the front end of the retaining ring 31, and a second rear nut 28 is screwed to the rear end of the retaining ring 31. The distance between the second front nut 27 and the second rear nut 28 at the rear end of the pull rod 24 is greater than the distance between the first flange 23 and the retaining ring 31.

[0078] The loading unit 12 is controlled to press the clamping component 30 against the soil. Then, the soil is slowly and evenly pressurized to avoid damaging the soil sample. At the same time, the reading of the first pressure sensor is observed and the pressure change is recorded. When the first pressure sensor reaches the preset pressure, the loading component 10 is turned off, and the pressure is maintained for more than 30 minutes to ensure that the soil sample is fully compacted.

[0079] After compaction, tighten the second rear nut 28. The second rear nut 28 cooperates with the second front nut 27 to clamp the retaining ring 31 and the first flange 23.

[0080] S40. Keep the piston 32 in contact with the soil, remove the inner plug 33, and obtain the basic data of the pressure stabilization stage. The basic data includes the porosity development of each soil section in the axial direction of the sleeve assembly 20.

[0081] The water supply unit is activated. The water supply unit is equipped with a flow meter and a second pressure sensor. The water supply unit gradually increases the water pressure according to the preset water pressure increase, and periodically acquires and records the porosity development of each soil section as dynamic data.

[0082] After observing the phenomenon of water inrush and mud bursting, water injection was stopped, and the porosity development of each soil section was obtained and recorded as damage data.

[0083] In this step, the loading assembly 10 is driven to move in the opposite direction, removing the inner plug 33. A high-definition camera is installed in the inner cavity of the piston 32 to observe the condition of the front face (i.e., the working face) of the soil. A ground-penetrating radar is used to perform a full-section scan of the soil. Specifically, the antenna of the ground-penetrating radar is moved parallel to the outside of the sleeve assembly 20 along the length of the sleeve assembly 20 to perform a full-section scan of the soil. The scanning range covers the entire circumferential section of the front cylinder 21 and the rear cylinder 22 to ensure that the structural changes of the soil in different radial directions are captured and the porosity development of the soil sample is recorded as basic data. Porosity development includes pore evolution and microcrack initiation.

[0084] The water supply components were started to conduct a water injection test. During water injection, the water pressure was gradually increased according to the preset water pressure increment, and then stabilized for a period of time after the water pressure was increased. During this stage, the ground-penetrating radar was used again to scan the entire cross section of the soil to obtain the porosity development of each soil section as dynamic data.

[0085] Dynamic data also includes the ability of ground-penetrating radar to scan the surface of the tunnel face through the cavity of piston 32 during the water injection experiment to obtain information on the porosity development of the tunnel face surface.

[0086] Dynamic data also includes high-definition camera images of the soil front face, such as failure patterns.

[0087] Dynamic data also includes scanning the soil immediately when the flow meter reading changes abruptly, obtaining information on the development of cracks in each soil cross-section and the front end of the soil as dynamic data.

[0088] During the water injection experiment, if the high-definition camera observes water inrush and mud bursting at the working face, water injection is immediately stopped. Ground-penetrating radar is then used with a higher scanning frequency and higher spatial resolution to scan the soil, obtain the porosity development of each soil section, and record it as damage data.

[0089] During the pressurization and stabilization phase, the initial porosity distribution of soil samples is identified and recorded through the "weak reflection zone" of radar wave reflection signals. During water injection, the weakening of reflection signals and local "strong reflection wave groups" are captured by timed scanning to characterize phenomena such as pore expansion and microcrack initiation. At the same time, the moment of crack penetration is captured by scanning during sudden changes in water pressure, reflecting the jump in reflection wave amplitude. After the occurrence of water inrush and mud inrush, the scanning frequency and spatial resolution can be increased to focus on capturing continuous reflection zones, the number and spacing of reflection zones, and the extension direction of reflection wave groups, and correspondingly record the morphology, distribution density, and spatial correlation of seepage channels with initial cracks.

[0090] S50. By combining basic data, dynamic data, and failure data, layer-by-layer comparisons are made to obtain the evolution rate of the soil internal structure at different stages, and then the threshold of critical permeability gradient is determined.

[0091] By comparing the basic data from the pressurization and stabilization phase, the dynamic data during water injection, and the post-failure data along the soil axis, structural changes at the same location are identified. Radar scan data is correlated in real time with the failure morphology of the tunnel face recorded by a high-definition camera and the pressure-flow data recorded by a dynamic instrument to establish a mapping relationship between "structural evolution - mechanical response - seepage behavior." Based on the above analysis, the pore expansion threshold, the critical condition for fracture penetration, and the indicators of pipe formation are determined. Furthermore, 3D modeling software is used to integrate pore distribution, fracture trajectory, and seepage channel morphology to generate a complete path diagram of the "pore-fracture-pipe" transformation.

[0092] During the pressurization and stabilization phase, the initial porosity distribution of the soil sample is identified and recorded through the "weak reflection zone" of the radar wave reflection signal. During water injection, the weakening of the reflection signal and local "strong reflection wave groups" are captured by timed scanning to characterize phenomena such as pore expansion and microcrack initiation. After the occurrence of water inrush and mud inrush, the scanning frequency and spatial resolution can be increased to focus on capturing continuous reflection zones, the number and spacing of reflection zones, and the extension direction of reflection wave groups, and correspondingly record the morphology, distribution density, and spatial correlation of seepage channels with the initial cracks.

[0093] The soil sample was divided into several layers along the axial direction, with each layer corresponding to an independent radar scan data unit. Data from the pressurization and stabilization stage, the water injection stage, and the post-fault stage of the same layer were aligned along the time axis. For each layer, key radar parameters at different stages were compared: the amplitude of reflected waves was used to characterize the pore concentration zone and the fracture development zone, and their continuity reflected the seepage channels; changes in travel time were used to characterize the changes in pores, fractures, and seepage channels; the combined distribution map of reflected wave amplitude and travel time was used to identify the key features of the "pore-fracture-channel" transformation, and the evolution rate was quantified and a threshold was determined; the structural evolution rate could be calculated based on the time intervals of different stages and the changes in radar parameters; when the evolution rate reached a certain critical value, the permeability gradient was inferred by combining the corresponding pressure-flow data, which is the critical threshold.

[0094] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. An apparatus for studying the mechanism of water inrush and mud inrush in fault muddy zones, characterized in that, include: The loading component (10) includes a reaction plate (11) and a loading unit (12) disposed on the reaction plate (11), wherein the movable end of the loading unit (12) is provided with a top rod (13). The sleeve assembly (20) includes a front sleeve (21) and a rear sleeve (22) communicating with the front sleeve (21), and the loading assembly (10) is disposed on the front side of the front sleeve (21); A clamping assembly (30) is disposed at the front end of the front cylinder (21). The clamping assembly (30) includes a retaining ring (31) and a piston (32) disposed in the inner ring of the retaining ring (31) and having open ends. An inner plug (33) is disposed inside the piston (32). The piston (32) and the inner plug (33) form a limiting structure (34) at the rear end of the piston (32). The push rod (13) is detachably connected to the inner plug (33). A water pressure assembly (40) is located at the rear end of the rear cylinder (22). The water pressure assembly (40) consists of a pressure plate (41), a water inlet plate (42), and a permeable plate (43) from back to front. The pressure plate (41) is fixed at the rear end of the rear cylinder (22). The pressure plate (41) is connected to the center hole of the water supply assembly. A water cavity is formed between the water inlet plate (42) and the pressure plate (41). The water inlet plate (42) is provided with several water inlet holes. The permeable plate (43) is in contact with the surface of the water inlet plate (42).

2. The apparatus for studying the mechanism of water inrush and mud inrush in fault mud zones according to claim 1, characterized in that: The reaction plate (11) is provided with a locking member (14) on the side facing the sleeve assembly (20). The locking member (14) is a three-quarter ring. The locking member (14) is concentrically arranged with the reaction plate (11). The locking member (14) is used to fix the loading unit (12).

3. The apparatus for studying the mechanism of water inrush and mud inrush in fault mud zones according to claim 2, characterized in that: The front cylinder (21) is provided with a first flange (23) at the front end, and the first flange (23) is provided with a first flange hole. The reaction plate (11) and the retaining ring (31) are respectively provided with a reaction hole and a through hole. The loading component (10) also includes a tie rod (24), which is sequentially inserted through the first flange hole, the through hole and the reaction hole. The tie rod (24) is provided with a first front nut (25) and a first rear nut (26) on the front and rear sides of the reaction plate (11), and a second front nut (27) and a second rear nut (28) on the front and rear sides of the first flange (23). A spring sheet (29) is provided between the first rear nut (26) and the reaction plate (11), and between the second front nut (27) and the retaining ring (31). A gasket is provided between the first front nut (25) and the reaction plate (11), and between the second rear nut (28) and the first flange (23). Several of the aforementioned tie rods (24) are arranged in a centrally symmetrical manner about the center of the reaction plate (11).

4. The apparatus for studying the mechanism of water inrush and mud inrush in fault mud zones according to claim 1, characterized in that: The rear end of the top rod (13) is provided with a rearward protruding connecting part, which is screwed to the inner plug (33).

5. The apparatus for studying the mechanism of water inrush and mud inrush in fault mud zones according to claim 1, characterized in that: The water inlet plate (42) has a protrusion (44) on the side facing the pressure plate (41), and the protrusion (44) abuts against the pressure plate (41) to form the water cavity.

6. A method employing the apparatus described in any one of claims 1-5 for studying the mechanism of water inrush and mud inrush in fault muddy zones, characterized in that, include: S10. Assemble the sleeve assembly (20) and the hydraulic assembly (40). S20. Fill the sleeve assembly (20) with soil, compact the soil and smooth the front end of the soil; S30. Assemble the clamping component (30) and the loading component (10), and use the loading component (10) to press the clamping component (30) against the soil. Observe the reading of the first pressure sensor. When the reading of the first pressure sensor reaches the preset pressure, close the loading component (10) and fix the clamping component (30). S40. Keep the piston (32) against the soil, remove the inner plug (33), and obtain the basic data of the pressure stabilization stage. The basic data includes the porosity of each soil section along the axial direction of the sleeve assembly (20). The water supply unit is activated. The water supply unit is equipped with a flow meter and a second pressure sensor. The water supply unit gradually increases the water pressure according to the preset water pressure increase, and periodically acquires and records the porosity development of each soil section as dynamic data. After observing the phenomenon of water inrush and mud bursting, water injection was stopped, and the porosity development of each soil section was obtained and recorded as failure data. S50. By combining basic data, dynamic data, and damage data, a complete path diagram of the "pore-fracture-pipe" transformation is constructed to obtain the evolution rate of the soil's internal structure at different stages, and then the threshold of the critical permeability gradient is determined.

7. The method according to claim 6, characterized in that: In step S40, when the flow meter reading changes abruptly, the porosity development of each soil section is immediately acquired and recorded as dynamic data.

8. The method according to claim 6, characterized in that: In step S40, ground-penetrating radar is used to scan each soil section and the front end of the soil to obtain information on pore development.

9. The method according to claim 6, characterized in that: In step S40, a high-definition camera is installed at the piston (32) to obtain an image of the front face of the soil.

10. The method according to claim 6, characterized in that: In step S50, by comparing the initial data, dynamic data and failure data of the same soil section at the same time node, a complete path diagram of the "pore-fracture-pipe" transformation is constructed.

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