A simulation test system and method for water inrush in a water-rich fracture zone of a submarine tunnel

Abstract

This invention relates to the field of subsea tunnel engineering model testing technology, and discloses a simulation test system and method for water inrush in a water-rich fault zone of a subsea tunnel. The system includes a model test chamber unit, defining the surrounding rock background, induced fracture zone, and fracture zone region; a similar material preparation unit, used to prepare a simulated material with permeability and strength gradients composed of a five-element material system; a multi-source combined loading unit, which applies constant hydrostatic pressure using an energy storage and pressure stabilization mechanism, and coordinates with the excitation module and excavation module to apply composite loads; and a monitoring and acquisition unit, used to capture physical field signals such as pore water pressure in real time and output sequential data. This invention constructs a heterogeneous model through partitioned proportioning, maintains water pressure balance under dynamic disturbances using energy storage and pressure stabilization technology, and combines multi-field coordinated mutation index calculation to achieve accurate reproduction of the entire process of water inrush disaster evolution and critical state identification.

Description

Technical Field

[0001] This invention relates to the field of submarine tunnel engineering model testing technology, specifically to a simulation test system and method for water inrush in a water-rich fault zone of a submarine tunnel. Background Technology

[0002] Submarine tunnel construction projects face complex geological environments and harsh hydrological conditions. When traversing fault zones, submarine tunnels are often subject to multiple influences, including high seawater pressure, tectonic movements, and disturbances caused by construction operations. To explore the evolution mechanism of water and mud inrush disasters in submarine tunnels and to formulate prevention and control measures, physical model tests are an important means of reproducing the mechanical behavior of deep rock masses under fluid-structure interaction environments.

[0003] Existing physical simulation experiments for submarine tunnels have limitations in the construction of scaled-down models. Physical model tests struggle to simultaneously satisfy both kinematic and dynamic similarity relationships while maintaining geometric similarity. Traditional single-component model materials cannot simultaneously reproduce the differentiated physical and mechanical behaviors of the weak fracture characteristics of the fault core and the developmental characteristics of fractures within the fault zone. Furthermore, the density, strength, and permeability parameters of the model materials often fail to create a heterogeneous structure and gradient distribution within the model test chamber that conforms to actual geological characteristics, leading to discrepancies between the self-weight stress field generated by the physical model and the engineering prototype.

[0004] When simulating the environment of deeply buried water-rich fault zones, experimental setups struggle to achieve stable loading under the coupling effects of high water pressure, intense excavation and unloading operations, and multi-field seismic dynamic disturbances. During the application of high-frequency dynamic loads conforming to seismic dynamics characteristics to the physical model by the excitation device, the fluid boundary pressure is easily disturbed by vibration, causing pulsations and leading to oscillations or failure of the hydrostatic pressure boundary conditions. These unstable boundary conditions prevent the physical model experiments from achieving decoupled control of dynamic and static loads, thus affecting the objectivity of observational data on the evolution mechanism of sudden water inrush disasters.

[0005] Conventional monitoring methods and data analysis techniques lack criteria for quantitatively characterizing the instability evolution of water-rich fault zones in submarine tunnels under the combined effects of excavation unloading and dynamic disturbances. Monitoring data often reflects isolated changes in single physical quantities such as pore water pressure or surrounding rock displacement, making it difficult to calculate comprehensive indicators reflecting the system's energy release rate and nonlinear response intensity through multi-physics field data fusion analysis. This makes it difficult for physical model tests to identify the critical time point for the water inrush channel to open. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a simulation test system and method for water inrush in seabed tunnels with water-rich fault zones. This solves the problem that existing physical simulation tests of seabed tunnels cannot simultaneously satisfy geometric, kinematic, and dynamic similarity relationships in scaled-down models, and in particular, cannot reproduce the heterogeneous water inrush disaster evolution mechanism of deeply buried water-rich fault zones under the multi-field coupling effects of high water pressure, strong excavation unloading, and seismic dynamic disturbances.

[0007] To achieve the above objectives, the first aspect of the present invention provides a simulation test system for water inrush in a water-rich fault zone of a submarine tunnel, comprising a model test chamber unit, a similar material preparation unit, a multi-source combined loading unit, and a monitoring and acquisition unit.

[0008] The model test chamber unit is configured to provide a physical space that satisfies the geometric similarity ratio and boundary constraints. This physical space defines a surrounding rock background region, an induced fracture zone region, and a fracture zone region, distributed sequentially along the axial direction. The induced fracture zone region and the fracture zone region form a spatially interconnected seepage channel to simulate the geological environment of a fracture structure.

[0009] The similar material preparation unit is used to determine and prepare the solid medium filling the model test chamber unit. The solid medium is composed of a five-element material system, specifically including induced fracture zone simulation material and fracture zone simulation material. This five-element material system constructs a heterogeneous fracture zone structure inside the model through the differentiated proportions of its components.

[0010] The multi-source combined loading unit is configured to apply composite loads to the model test chamber unit, including excitation loads conforming to seismic dynamics characteristics, constant hydrostatic pressure boundaries, and simulated excavation unloading operations. The multi-source combined loading unit includes an excitation control module, a hydraulic loading module, and an excavation simulation module, used to drive the generation of shear vibration response and seepage field evolution within the model.

[0011] The monitoring and acquisition unit is configured to capture the physical field evolution signals inside the model in real time and output standardized time-physical quantity sequence data.

[0012] Furthermore, the model test chamber unit comprises a rigid model box consisting of six orthogonal constraint planes. The front constraint panel is equipped with a horseshoe-shaped tunnel entrance reserved interface and a drainage channel interface, used to simulate the excavation free face and to drain the inrush water mixture, respectively; the upper constraint panel is equipped with uniformly distributed water injection pressure-bearing interfaces, connected to the water pressure loading module. The geological structure layout module, through spatial definition, ensures that the induced fracture zone area and the fractured zone area form a seepage channel connecting the upper water pressure boundary and the lower tunnel excavation space.

[0013] Furthermore, the five-element material system defined by the similar material preparation unit includes quartz sand, iron concentrate, white cement, gypsum, and water. By setting the iron sand ratio and white cement content as core control parameters through a partitioned proportioning module, the density and cementing strength of the materials are adjusted respectively, thereby constructing a permeability gradient and strength gradient within the model that conforms to actual geological characteristics.

[0014] Furthermore, the hydraulic loading module employs a servo-controlled constant-pressure water supply mechanism including an energy storage regulator. During the application of high-frequency dynamic loads by the vibration control module, this servo-controlled constant-pressure water supply mechanism utilizes the energy storage regulator to absorb fluid pressure fluctuations, maintaining a dynamic balance of boundary water pressure and achieving decoupled control of dynamic and static loads. The excavation simulation module is configured to perform step-by-step material removal operations and adopts a cyclical operation mode of pressure-reducing excavation and pressure-maintaining vibration to simulate stress redistribution during the tunneling process.

[0015] Furthermore, the monitoring and acquisition unit determines the axial coordinate position of the key monitoring section based on the composite width of the fault zone. Miniature pore water pressure sensors and miniature earth pressure cells are deployed within the key monitoring section, and multi-point displacement gauges are used to monitor the displacement of the surrounding rock, thereby comprehensively acquiring data on the seepage field, stress field, and displacement field.

[0016] The second aspect of this invention provides a method for simulating water inrush in a water-rich fault zone of a submarine tunnel, applied to a system for simulating water inrush in a water-rich fault zone of a submarine tunnel, comprising the following steps:

[0017] A conversion benchmark for physical quantities between the prototype and model test chamber units of the submarine tunnel project is established. Stress similarity constants, time similarity constants, and permeability coefficient similarity constants are derived using geometric similarity constants and unit weight similarity constants, thereby determining the set of target values ​​for physical and mechanical parameters.

[0018] Based on the target set of physical and mechanical parameters, the mass ratio of the five-element material system was adjusted using the partitioning and proportioning module in the similar material preparation unit to prepare simulated materials for induced fracture zones and simulated materials for fracture zones.

[0019] The aforementioned materials and surrounding rock background materials were filled into the model test chamber unit, and sensors were simultaneously embedded to form a consolidation physical model.

[0020] A constant hydrostatic pressure boundary was constructed at the boundary of the consolidation physical model using a multi-source co-loading element. The stability of the initial seepage field was determined by calculating the instantaneous fluctuation rate of the seepage field, which was based on the ratio of the pore water pressure difference between adjacent time points to the current value.

[0021] The excavation simulation module and vibration control module operate collaboratively to perform step-by-step excavation and dynamic disturbance on the consolidated physical model. The step-by-step excavation and dynamic disturbance process adopts a cyclical operation mode: first, water pressure is temporarily blocked and boundary pressure is removed, and the material at the current step distance is removed; then, the interface is closed and boundary water pressure is restored; finally, periodic dynamic loads are applied. During the step-by-step excavation and dynamic disturbance process, the critical state identification coefficient for water inrush in the fracture zone is calculated in real time. The critical state identification coefficient is calculated based on the effective vertical stress, shear strength parameters, current static pore water pressure, and the increment of dynamically excited excess pore water pressure. When the critical state identification coefficient is less than a preset safety threshold, a water inrush disaster is determined to have occurred, the experiment is stopped, and the data is saved.

[0022] The characteristics of the entire process test data are analyzed, and the multi-field synergistic mutation index of seepage stress and displacement is calculated to determine the critical time node for the breakthrough of the water inrush channel.

[0023] Furthermore, in the material preparation steps, the basic skeleton density of the model material is controlled by the iron-to-sand ratio (mass ratio of iron concentrate to quartz sand), and the cementitious strength and compressive modulus are controlled by the white cement content (proportion of white cement to total solid mass). For the simulated material of the fracture zone, compared with the simulated material of the induced fracture zone, the mass fraction of white cement is reduced and the mass fraction of water is increased to simulate the weak mechanical behavior and high permeability of fault gouge.

[0024] Furthermore, the calculation method for the multi-field synergistic mutation index of seepage stress-displacement is as follows: extract the time history curves of pore water pressure, contact stress, and surrounding rock displacement, and calculate the time change rate of each physical quantity. After normalizing the time change rate of each physical quantity by dividing it by the corresponding reference value, perform a square operation. Finally, sum the squared values ​​of each item by weight to obtain a comprehensive index reflecting the system's energy release rate and nonlinear response intensity.

[0025] This invention provides a system and method for simulating water inrush in a water-rich fault zone of a submarine tunnel. It has the following beneficial effects:

[0026] 1. This invention defines a five-element material system consisting of quartz sand, iron concentrate, white cement, gypsum, and water through a similar material preparation unit. Iron concentrate is used to adjust the material density, while white cement and gypsum are used to adjust the bonding strength and brittleness. A zoned proportioning module is used to implement differentiated mass proportioning schemes for the induced fracture zone and the fracture zone. A heterogeneous fracture zone structure with permeability and strength gradients is constructed inside the model test chamber unit, realizing the physical reproduction of the weak fracture characteristics and fracture development characteristics of the fracture zone core. This ensures that the model material simultaneously meets the similarity theory requirements in terms of density, strength, and permeability.

[0027] 2. This invention employs a servo-controlled constant pressure water supply mechanism with an energy storage regulator in the water pressure loading module of the multi-source combined loading unit. During the process of the vibration control module applying high-frequency dynamic loads to the model test chamber unit, the energy storage regulator absorbs the fluid pressure pulsations caused by vibration, and the servo-controlled constant pressure water supply mechanism maintains constant pressure at the water injection pressure interface. This eliminates the interference of dynamic disturbances on the hydrostatic pressure boundary conditions, realizes stable coupling loading of seismic dynamic loads and high-pressure fluid environment, and ensures the accuracy of boundary conditions in the water inrush simulation test.

[0028] 3. This invention adopts a cyclic operation mode of pressure reduction excavation and pressure-maintaining vibration, combined with the calculation method of multi-field synergistic mutation index of seepage stress and displacement. The monitoring and acquisition unit acquires time series data of pore water pressure, contact stress and surrounding rock displacement in real time, and performs weighted square summation analysis on the time change rate of pore water pressure, contact stress and surrounding rock displacement. It provides a criterion for quantitatively characterizing the instability evolution process of water-rich fault zone in submarine tunnel under the superposition of excavation unloading and dynamic disturbance, and can identify the critical time node of water inrush channel connection. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the overall structure of the system of the present invention;

[0030] Figure 2 This is a schematic diagram of the experimental process of the method of the present invention.

[0031] Among them, 100 is the model test chamber unit; 200 is the similar material preparation unit; 300 is the multi-source combined loading unit; and 400 is the monitoring and acquisition unit. Detailed Implementation

[0032] The technical solutions in 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 embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] See attached document Figure 1 The present invention provides a simulation test system for water inrush in a water-rich fault zone of a submarine tunnel, comprising: a model test chamber unit 100, a similar material preparation unit 200, a multi-source combined loading unit 300, and a monitoring and acquisition unit 400.

[0034] The model test chamber unit 100 is configured to provide a physical space that satisfies the geometric similarity ratio and boundary constraints. The model test chamber unit 100 defines the physical boundary of the water inrush simulation test system of the water-rich fault zone of the submarine tunnel. The model test chamber unit 100 includes a rigid model chamber.

[0035] The rigid model box adopts a cubic structure, with its internal effective length, width, and height dimensions set at 1000mm × 1000mm × 1000mm. The spatial dimensions of the rigid model box are set based on the geometric similarity constant determined by the second similarity theorem. In this embodiment, the geometric similarity constant is defined as the ratio of the characteristic length of the prototype of the submarine tunnel project to the characteristic length of the model, with a value of 100. That is, 1000mm of physical scale within the model corresponds to 100m of geological range in the actual project, thereby constructing a scaled-down physical space that meets the requirements of the deep-buried submarine tunnel environment.

[0036] The rigid model box consists of six orthogonal constraint planes: the front constraint panel, the rear constraint panel, the upper constraint panel, the lower constraint bottom plate, the left constraint side plate, and the right constraint side plate.

[0037] The front constraint panel is equipped with a horseshoe-shaped tunnel entrance pre-reserved interface and a drainage channel interface. The horseshoe-shaped tunnel entrance pre-reserved interface is used to simulate the free face of the excavation of a submarine tunnel. The position coordinates of the horseshoe-shaped tunnel entrance pre-reserved interface are determined by converting the relative position of the tunnel in the fault zone in actual engineering through geometric similarity constant conversion. The drainage channel interface connects the inside of the rigid model box with the external environment. The drainage channel interface is used to drain the gushing water and sediment mixture when a water inrush occurs, ensuring the continuity of the water inrush process.

[0038] The rear constraint panel is configured with a detachable sealing structure. The detachable sealing structure is opened after the test to clean the waste filling material and mud inside the rigid model box, realizing the recycling of the water inrush simulation test system for the water-rich fault zone of the submarine tunnel.

[0039] The upper constraint panel is equipped with evenly distributed water injection and pressure bearing interfaces. These interfaces are used to connect to external water pressure loading pipelines to apply constant water pressure to the inside of the rigid model box, simulating the hydrostatic pressure boundary conditions generated by the seawater overlying the undersea tunnel.

[0040] High-pressure sealing media are installed at all connection points of the constraint planes of the rigid model box. This high-pressure sealing media, combined with a high-strength bolt array, ensures that no fluid leakage or stiffness failure occurs at these connection points when the rigid model box is subjected to dynamic disturbances of 10 kPa hydrostatic pressure and a peak acceleration of 10.0 m / s². The structural stiffness of the rigid model box must be much greater than the elastic modulus of the internal filling material to eliminate the interference of boundary effects on the internal stress field distribution, ensuring that the model test box unit 100 can accurately reproduce the stress environment of the deep rock mass.

[0041] The model test chamber unit 100 includes a geological structure layout module, which is configured to establish the relative positional relationship between the geological model and the engineering structure in a three-dimensional spatial coordinate system inside the rigid model chamber.

[0042] The geological structure layout module divides the internal filling space of the rigid model box into a surrounding rock background area, an induced fracture zone area, and a fracture zone area. The surrounding rock background area, induced fracture zone area, and fracture zone area are distributed sequentially along the axis perpendicular to the front constraint panel.

[0043] The geological structure layout module defines a tunnel axis within the rigid model box. The tunnel axis originates at the center of the horseshoe-shaped tunnel entrance pre-reserved interface on the front constraint panel, extending horizontally and traversing the induced fracture zone and the fractured zone. The tunnel axis serves to guide the excavation direction in subsequent construction excavation simulations.

[0044] The induced fracture zone is defined as a transitional geological space surrounding or adjacent to the fracture zone. It simulates a geological environment where fractures are developed due to fault structures, but the rock mass structure remains intact. The fracture zone is defined as the core area of ​​the fault structure. It simulates a geological environment where the rock mass is extremely fractured, poorly cemented, and highly water-bearing.

[0045] The simulated widths of the induced fracture zone and the fracture zone are strictly scaled down based on the geometric similarity constant (valued at 100). That is, the simulated width of each region in the rigid model box is equal to the actual width of the corresponding geological region in the engineering prototype divided by the geometric similarity constant, thereby restoring the true spatial proportion of the fracture zone within the rigid model box.

[0046] The geological structure layout module ensures that the induced fracture zone and the fractured zone form a continuous seepage channel within the rigid model box. This continuous seepage channel connects the pressure-bearing interface of the upper constraint panel to the potential excavation space along the tunnel axis, providing the necessary spatial geometry for subsequent simulations of high-pressure seawater intrusion into the tunnel along the fracture zone. The geological structure layout module also defines the contact interfaces between the induced fracture zone and the fractured zone and the sidewalls of the rigid model box. These contact interfaces require anti-leakage treatment to ensure that the seepage field evolves only along the fracture zone's direction and vertically.

[0047] The similar material preparation unit 200 is configured to determine and prepare a solid medium for filling the model test chamber unit 100 based on similarity theory and orthogonal experimental logic.

[0048] The similar material preparation unit 200 includes a material selection module and a partitioning and proportioning module.

[0049] The materials selection module defines a five-element material system, which includes: quartz sand, iron concentrate, white cement, gypsum, and water. Each component in the five-element material system is selected based on specific physicochemical properties to meet the mechanical and seepage similarity requirements of the water-rich environment of the subsea tunnel.

[0050] Quartz sand is defined as an inert aggregate. In the five-element material system, quartz sand provides basic volumetric support and frictional strength. The particle size distribution curve of quartz sand determines the basic morphology of the initial pore structure within the material. Iron concentrate is defined as a density modifier. Iron concentrate has a density much higher than ordinary soil and rock materials. The proportion of iron concentrate added is used to increase the overall bulk density of the model material, thereby achieving density similarity while meeting the geometric similarity ratio, ensuring that the self-weight stress field generated by the model is consistent with the engineering prototype.

[0051] White cement is defined as the primary binder. White cement undergoes a hydration reaction with water to form a gel, which connects the quartz sand and iron concentrate particles, providing the model material with compressive strength and cohesion. Gypsum is defined as an auxiliary binder and brittleness modifier. The hydration products of gypsum regulate the initial setting time and residual strength of the model material after fracture. Gypsum causes the model material to exhibit brittle fracture characteristics consistent with rock properties, rather than plastic flow characteristics, upon fracture.

[0052] The material selection module determines the target parameter range of each physical quantity based on the fluid-structure interaction similarity control equation. By strictly following the similarity theory, the unit weight similarity constant is set to 1, which requires that the unit weight of the model material be consistent with that of the prototype. At the same time, the stress similarity constant and the permeability coefficient similarity constant are derived based on the geometric similarity constant (with a value of 100) to ensure that the stress field distribution and seepage field evolution in the model maintain a strict physical mapping relationship with the engineering prototype on a spatiotemporal scale.

[0053] The material selection module specifically sets up a hydrophysical stability criterion for the seabed's water-rich environment. This criterion requires that the model material not disintegrate or soften and become muddy under prolonged immersion in water. The composite cementing structure formed by white cement and gypsum endows the model material with resistance to water disintegration, ensuring that under a constant water pressure of 10 kPa and a dynamic disturbance of 5 Hz applied by the model test chamber unit 100, the skeletal structure of the induced fracture zone and broken zone remains intact. Seepage evolution occurs only through the transmission of pore water pressure and fracture propagation, rather than the dissolution and destruction of the material itself.

[0054] The partitioning module is configured to output differentiated material quality combinations for different geological spaces defined in the model test chamber unit 100, so as to reconstruct the heterogeneous fault zone structure in the physical model.

[0055] Based on the differences in the physical and mechanical properties of the rock mass within the fracture zone, the partitioning and proportioning module divides the material control targets into simulated materials for induced fracture zones and simulated materials for fracture zones. The module sets the iron sand ratio and white cement content as core control parameters. The iron sand ratio is defined as the ratio of the mass of iron concentrate to the mass of quartz sand, and is used to control the basic skeleton density of the model material. The white cement content is defined as the proportion of white cement mass to the total solid mass, and is used to adjust the cementing strength and compressive modulus of the model material.

[0056] For the induced fracture zone area, the zoning and proportioning module implements the first mass proportioning scheme. The first mass proportioning scheme aims to simulate the characteristics of well-developed fractures but relatively intact rock mass at the edge of the fracture zone. The mass ratio of each component in the first mass proportioning scheme follows a specific proportioning logic, setting the mass ratio of iron concentrate, quartz sand, white cement, gypsum, and water to 1:1.5:0.04:0.10:0.03 to ensure that the materials have the self-stabilizing capacity required to maintain the free face of the tunnel excavation.

[0057] For the fractured zone area, the zoning module implements a second mass proportioning scheme. This second scheme aims to simulate the characteristics of the core rock mass of the fault zone: extremely fractured, weakly cemented, and highly water-rich. In this scheme, the mass fraction of white cement is reduced to 0.02%, and the mass fraction of water is increased to 0.04%, while the remaining components remain unchanged. The reduction in white cement content simulates the weak mechanical behavior of fault gouge, while the increase in water content enhances internal pore connectivity, thereby forming preferential water inrush channels.

[0058] The partitioned mix design module constructs permeability and intensity gradients within the rigid model box by controlling the differences between the first and second mass mix design schemes. These gradients guide pore water pressure to be released towards the free face of the tunnel excavation along the fractured zone under dynamic disturbance, accurately recreating the water and mud inrush disaster mechanism when a submarine tunnel crosses a fault zone.

[0059] The multi-source combined loading unit 300 is configured to apply an excitation load conforming to the characteristics of seismic dynamics to the model test chamber unit 100. The multi-source combined loading unit 300 drives the induced fracture zone region and the fracture zone region inside the model test chamber unit 100 to generate a shear vibration response. The multi-source combined loading unit 300 includes an excitation control module, a hydraulic loading module, and an excavation simulation module.

[0060] The vibration control module is configured to generate acceleration time-history signals that control the output of the associated vibrator. Based on the engineering geological survey data of the undersea tunnel site, the vibration control module determines the waveform form, frequency parameters, and amplitude range of the dynamic loading. The vibration control module simplifies the complex random seismic wave signal into a standard sine wave signal, which can accurately reproduce the cyclic tension and shear effects of seismic loads on rock fractures.

[0061] The vibration control module determines the loading frequency based on the dominant period parameter of Class I site in the prototype area of ​​the undersea tunnel project. The dominant period parameter is 0.20s, corresponding to the dominant seismic wave frequency (5Hz) in the actual project. The vibration control module sets the loading frequency to 10Hz to satisfy the dynamic similarity relationship and excite the resonance response of the model material inside the model test chamber unit 100.

[0062] The excitation control module controls the output of the excitation force through the acceleration time history function, and adopts a standard sine wave form, using the peak acceleration as the amplitude control parameter and a fixed frequency of 10Hz as the time control parameter to generate a continuous simple harmonic excitation signal, which is applied to the bottom of the model test chamber unit 100.

[0063] The excitation control module is equipped with a peak ground acceleration (PGA) adjustment mechanism. This mechanism maps seismic intensity levels to specific acceleration values ​​based on the Chinese seismic intensity scale. The PGA adjustment mechanism sets the PGA to 0.65 m / s² when simulating a seismic intensity of VI, and to 5.77 m / s² when simulating a seismic intensity of IX. This PGA adjustment mechanism allows the multi-source combined loading unit 300 to continuously adjust the excitation intensity within the range of 0.65 m / s² to 5.77 m / s², covering the entire seismic intensity range from slight disturbance to extremely severe damage.

[0064] The hydrostatic loading module is configured to construct a constant hydrostatic pressure boundary at the upper constraint panel of the model test chamber unit 100. The hydrostatic loading module simulates the environment of an infinite water supply source provided by the seawater overlying the submarine tunnel.

[0065] The hydraulic loading module is connected to the water injection and pressure bearing interface of the upper constraint panel via an external hydraulic loading pipeline. The hydraulic loading module employs a servo-controlled constant pressure water supply mechanism equipped with an energy storage regulator. This mechanism can monitor and adjust the water pressure inside the model test chamber unit 100 in real time. When pressure fluctuations occur inside the model test chamber unit 100 due to vibration generated by the vibration control module or water inrush caused by excavation, the hydraulic loading module maintains the pressure through the servo-controlled constant pressure water supply mechanism, thus maintaining the dynamic balance of the hydraulic boundary pressure.

[0066] The hydraulic loading module calculates the target loading pressure at the model boundary based on the seawater depth and stress similarity constant of the prototype submarine tunnel project. After considering the geometric scaling effect and the correction of the hydraulic loading intensification coefficient, the boundary hydrostatic pressure is set to 10 kPa to generalize the simulation of the water-rich environment in which the submarine tunnel is located.

[0067] The hydraulic loading module features pressure-vibration decoupling functionality. The vibration control module controls the accompanying exciter to apply a 5Hz frequency with a maximum acceleration of 5.77 m / s². 2 During the seismic loading period, the hydraulic loading module utilizes an energy storage regulator to absorb fluid pressure fluctuations caused by high-frequency vibrations, ensuring that the boundary water pressure remains stable at the set value of 10 kPa. This stable hydraulic boundary condition guarantees the accuracy of subsequent water inrush test data and eliminates false seepage monitoring signals caused by boundary pressure oscillations.

[0068] The excavation simulation module is configured to perform step-by-step material removal operations inside a rigid model box. The excavation simulation module simulates the release and redistribution of surrounding rock stress during the excavation of an undersea tunnel.

[0069] The excavation simulation module discretizes the continuous tunnel excavation process into several independent excavation cycles. Each excavation cycle includes a material removal stage and a stress balance monitoring stage. The excavation simulation module controls the spatial advancement of the material removal stage by setting excavation step distance parameters. The excavation step distance parameters are determined based on the design cycle advance and geometric similarity constants of the prototype submarine tunnel project.

[0070] The excavation simulation module uses geometric similarity constants to scale down the design cycle advance of the engineering prototype, sets the single excavation step distance in the model test to 30mm (corresponding to 3m in the actual project), and determines the total number of excavation cycles required to traverse the entire induced fracture zone and fracture zone.

[0071] The excavation simulation module generates spatial coordinate commands during the material removal phase. These commands define the volume of solid media to be removed in the current excavation cycle. The module ensures that the material removal operation proceeds sequentially along the tunnel axis, from the front constraint panel to the rear constraint panel. The module strictly limits the volume of material removed in a single operation to prevent over-excavation from causing abrupt changes in the stress field within the rigid model box, which could mask the precursory information of a gradual water inrush disaster.

[0072] The excavation simulation module executes a static waiting procedure during the stress balance monitoring phase. This procedure is configured to maintain the current excavation face state until the surrounding rock deformation rate stabilizes after a material removal operation is completed. The duration of the static waiting procedure is determined based on the fluid-structure interaction seepage evolution time ratio to match the permeability coefficient evolution rate set in the similar material preparation unit 200.

[0073] The excavation simulation module maintains time synchronization with the vibration control module and the hydraulic loading module. The excavation simulation module employs a cyclical operation mode of depressurized excavation and pressure-maintaining vibration. During material removal operations, the input circuit of the hydraulic loading module is temporarily shut off, and a detachable sealing structure is used for rapid soil removal. The module is then immediately resealed and the hydrostatic pressure is restored to 10 kPa. Through this combined loading mode, the excavation simulation module recreates the entire process of water inrush evolution in the fracture zone under the combined effects of excavation unloading, dynamic disturbance, and high-pressure seepage in the physical model.

[0074] The monitoring and acquisition unit 400 is configured to capture in real time the physical field evolution signals inside the model test chamber unit 100 caused by dynamic disturbances and excavation unloading. The monitoring and acquisition unit 400 includes a measuring point layout module and a data processing module.

[0075] The measuring point layout module defines the three-dimensional spatial coordinate distribution of various monitoring elements within the rigid model box. The monitoring elements selected for this module include: a micropore water pressure sensor, a micro earth pressure cell, and a multi-point displacement gauge. The micropore water pressure sensor is configured to monitor changes in fluid pressure gradient within the induced fracture zone and the fractured zone. The micro earth pressure cell is configured to monitor the redistribution of surrounding rock stress and the state of compressive stress. The multi-point displacement gauge is configured to monitor tunnel arch settlement and extrusion deformation at the tunnel excavation face.

[0076] In this embodiment, the monitoring point layout module plans the spatial distribution of monitoring sections along the tunnel axis based on the principle of denser monitoring in key areas and sparser monitoring in background areas. The module focuses on high-density monitoring coverage of the fault zone's influence area. The module determines the axial coordinate position of the key monitoring sections based on the composite width of the fault zone. The formula for calculating the axial coordinate position of the key monitoring sections is as follows:

[0077] ;

[0078] ;

[0079] In the formula, Defined as the first The absolute coordinates of the key monitoring sections along the tunnel axis, with the origin at the tunnel entrance; Defined as the axial coordinate value of the geometric center of the fracture zone region; Defined as the first Location distribution coefficients of key monitoring sections The set of values ​​is set as The location distribution coefficient is used to ensure that the monitoring section completely covers the leading edge, center, and trailing edge of the fault zone; Defined as the composite simulation width of the fault zone's influence area; Defined as the simulated width of the fracture zone region; Defined as the simulated width of the induced fracture zone region.

[0080] The monitoring point layout module employs a radial arrangement of monitoring points within the two-dimensional plane of each key monitoring section. Centered on the tunnel axis, the module embeds miniature pore water pressure sensors and miniature earth pressure cells at four characteristic locations: the tunnel arch crown, arch bottom, left arch waist, and right arch waist. The module specifies that the sensing surfaces of the miniature pore water pressure sensors and miniature earth pressure cells must be perpendicular to the expected principal stress direction or seepage vector direction to maximize signal acquisition sensitivity.

[0081] The measuring point layout module performs specific path planning for the placement of multi-point displacement gauges. The multi-point displacement gauges extend from the top of the rigid model box to above the tunnel arch, perpendicular to the tunnel axis. Dynamic sealing flanges are installed at the points where the measuring rods of the multi-point displacement gauges pass through the upper constraint panel to ensure no fluid leakage occurs at the perforations in the upper constraint panel when the rods undergo relative displacement or when the model box is subjected to 10 kPa water pressure. The measuring point anchorages of the multi-point displacement gauges are located at the interface between the induced fracture zone and the surrounding rock background zone, as well as within the fractured zone. The measuring point layout module uses the differentiated deformation data from the multi-point displacement gauges to quantitatively analyze the expansion range of the loosened zone of the fractured rock mass under the action of the multi-source combined loading unit 300.

[0082] The data processing module is configured to perform digital conversion, time-series alignment, and noise reduction and cleaning on the multi-physics field analog signals obtained from the measurement point layout module, and output standardized time physical quantity sequence data.

[0083] The data processing module establishes a unified time reference axis. It synchronously activates the data recording channels of the micro pore water pressure sensor, micro earth pressure cell, and multi-point displacement gauge via hardware triggering. The data processing module uses the excitation start signal output by the multi-source combined loading unit 300 as the global trigger zero point (T0). This global trigger zero point ensures that the data recorded by all monitoring channels are strictly corresponding in the time dimension, eliminating clock drift errors between different acquisition devices.

[0084] Based on the sampling theorem, the data processing module sets the data acquisition frequency to five times the highest frequency of dynamic loading (10Hz) (i.e., 50Hz) to ensure complete reproduction of the fluctuation waveforms of pore water pressure and surrounding rock stress. The acquired analog voltage signals are converted into specific physical quantity values ​​through a pre-calibrated linear relationship. To address the high-frequency mechanical noise generated by the servo-controlled constant pressure water supply mechanism, the data processing module introduces a weighted moving average filtering algorithm with a sliding window length of 5, which removes background noise interference while preserving the low-frequency seepage evolution trend and the 5Hz dynamic response characteristics.

[0085] The data processing module calculates the abrupt change characteristic indicators of physical quantities in real time. As one of the abrupt change characteristic indicators, the data processing module identifies the onset time of a water inrush disaster by monitoring the instantaneous rate of change of pore water pressure. When the gradient of the filtered pore water pressure data between adjacent sampling points exceeds a preset threshold, the data processing module determines that a through-type failure has occurred within the fracture zone and automatically marks this onset time as the water inrush occurrence time.

[0086] See attached document Figure 2 This invention provides a method for simulating water inrush in a water-rich fault zone of a submarine tunnel, comprising the following steps:

[0087] S1. Establish a physical quantity conversion benchmark between the prototype of the submarine tunnel project and the model test box unit 100. Based on the effective internal length, width, and height dimensions of the rigid model box and the geological range (100m) of the submarine tunnel project prototype, determine the value of the geometric similarity constant. The geometric similarity constant is defined as the ratio of the characteristic length of the submarine tunnel project prototype to the characteristic length of the rigid model box, and is set to 100.

[0088] Based on the density adjustment capability of the five-element material system defined in the material selection module of the similar material preparation unit 200, the density similarity constant is determined. Since iron concentrate, as a density regulator, can increase the overall bulk density of the model material, the density similarity constant is set to 1. The density similarity constant is defined as the ratio of the density of the prototype rock mass material of the submarine tunnel project to the density of the filling material inside the model test chamber unit 100.

[0089] Based on the second similarity theorem, the stress similarity constant, time similarity constant, and permeability coefficient similarity constant are derived using geometric similarity constants and unit weight similarity constants to ensure that the physical field evolution law inside the model test chamber unit 100 is consistent with the prototype of the submarine tunnel project. The calculation formulas for the stress similarity constant, time similarity constant, and permeability coefficient similarity constant are shown below:

[0090] ;

[0091] ;

[0092] ;

[0093] In the formula, Defined as a stress similarity constant, the stress similarity constant is used to guide the boundary hydrostatic pressure value set by the water pressure loading module and the material compressive strength value set by the partition ratio module; Defined as a similarity constant, with a value of 1; Defined as a geometric similarity constant, with a value of 100; Defined as a time similarity constant, the time similarity constant is used to map the frequency and duration of the dynamic load applied by the multi-source joint loading unit 300 to the time scale of the engineering prototype; Defined as the permeability coefficient similarity constant, the permeability coefficient similarity constant is used to determine the target permeability performance index of the simulated material of the induced fracture zone and the simulated material of the fracture zone in the similar material preparation unit 200.

[0094] The specific set of target physical and mechanical parameters is calculated using the above formula. This set includes: the target value of the boundary water pressure to be applied inside the model test chamber unit 100; the target uniaxial compressive strength of the filling material in the induced fracture zone and fractured zone; and the target permeability coefficient of the filling material in the induced fracture zone and fractured zone. This set of target physical and mechanical parameters is then transmitted as input data to the similar material preparation unit 200 and the multi-source combined loading unit 300 to control subsequent material preparation processes and loading control parameters.

[0095] S2. Based on the output set of target physical and mechanical parameters, a solid medium for filling the model test chamber unit 100 is prepared using the similar material preparation unit 200. A model material that meets the mechanical and seepage similarity requirements of the water-rich environment of the submarine tunnel is constructed using the five-element material system (quartz sand, iron concentrate, white cement, gypsum, and water) defined by the material selection module.

[0096] The iron sand ratio and white cement content are set as core control parameters using the zone proportioning module. The zone proportioning module controls the basic skeleton density of the model material by adjusting the iron sand ratio, and controls the cementing strength and compressive modulus of the model material by adjusting the white cement content. The calculation formulas for the iron sand ratio and white cement content are shown below:

[0097] ;

[0098] ;

[0099] In the formula, Defined as iron-to-sand ratio; Defined as the mass of iron concentrate in a five-element material system; Defined as the mass of quartz sand in a five-element material system; Defined as white cement content; Defined as the mass of white cement in a five-element material system; Defined as the total mass of all solid components in a pentagonal material system.

[0100] The first mass proportioning scheme was implemented for the induced fracture zone area. The zonal proportioning module determined the mass proportions of each component of the simulated material for the induced fracture zone based on the first mass proportioning scheme. The first mass proportioning scheme set the mass ratio of iron concentrate, quartz sand, white cement, gypsum, and water to 1:1.5:0.04:0.10:0.03. The first mass proportioning scheme was used to simulate the physical characteristics of the rock mass at the edge of the fracture zone, where fractures were developed but the framework was relatively intact.

[0101] A second mass proportioning scheme was implemented for the fractured zone area. The zonal proportioning module determined the mass proportions of each component of the simulated material for the fractured zone based on this second scheme. The second mass proportioning scheme, based on the first scheme, adjusted the mass fraction of white cement to 0.02 and the mass fraction of water to 0.04, while keeping the mass fractions of iron concentrate, quartz sand, and gypsum unchanged. Reducing the white cement content simulates the weak mechanical behavior of fault gouge, while increasing the water content enhances the pore connectivity within the simulated material for the fractured zone.

[0102] The induced fracture zone simulation material and the fracture zone simulation material are prepared by stirring according to the determined mass ratio. The prepared induced fracture zone simulation material and fracture zone simulation material are output for subsequent steps to construct a heterogeneous fracture zone structure with permeability coefficient gradient and intensity gradient inside a rigid model box.

[0103] S3. Fill the model test chamber unit 100 with the output simulated fracture zone material, simulated fracture zone material, and surrounding rock background material. Based on the spatial relationships defined by the geological structure layout module in the model test chamber unit 100, construct the surrounding rock background area, induced fracture zone area, and fracture zone area inside the rigid model chamber. Ensure that the surrounding rock background area, induced fracture zone area, and fracture zone area are distributed sequentially along the axis perpendicular to the front constraint panel.

[0104] By defining the measuring point layout module in the monitoring and acquisition unit 400, micro pore water pressure sensors, micro earth pressure cells, and multi-point displacement gauges are simultaneously installed during the filling process. The axial coordinate position of the key monitoring section is determined based on the composite width of the fracture zone.

[0105] Within the two-dimensional plane of each key monitoring section, miniature pore water pressure sensors and miniature earth pressure cells are embedded at four characteristic locations—the tunnel arch crown, arch bottom, left arch waist, and right arch waist—with the tunnel axis as the center. The sensing surfaces of the miniature pore water pressure sensors and miniature earth pressure cells are placed perpendicular to the expected principal stress direction or seepage vector direction.

[0106] The multi-point displacement gauges were inserted from the top of the rigid model box to above the tunnel arch, perpendicular to the tunnel axis. The anchoring points of the multi-point displacement gauges were set at the interface between the induced fracture zone and the surrounding rock background zone, as well as inside the fractured zone. After the filling and installation operations were completed, a consolidated physical model was formed, containing a complete monitoring network and having a horseshoe-shaped tunnel entrance reserved interface.

[0107] S4. Introduce a fluid medium into the output consolidation physical model to simulate the high-pressure, water-rich state under the deep-buried environment of a submarine tunnel. Using the water pressure loading module in the multi-source combined loading unit 300, a constant hydrostatic pressure boundary is constructed at the upper constraint panel of the model test chamber unit 100.

[0108] Connect the water pressure loading module to the water injection pressure-bearing interface on the upper constraint panel via an external water pressure loading pipeline. Activate the servo-controlled constant pressure water supply mechanism, which is equipped with an energy storage and pressure stabilizing unit within the water pressure loading module. Based on the target values ​​of the output physical and mechanical parameters, set the output pressure of the servo-controlled constant pressure water supply mechanism to 10 kPa.

[0109] Water was continuously injected into the rigid model box until it reached saturation. The monitoring and acquisition unit 400 was used to read the values ​​from the micropore water pressure sensor in real time. The initial seepage field equilibrium was determined based on the sensor readings, eliminating unsteady turbulence interference during the initial water injection phase and ensuring that subsequent experiments were conducted on a stable hydrostatic pressure boundary. The initial seepage field equilibrium determination formula is as follows:

[0110]

[0111] In the formula, Defined as the instantaneous fluctuation rate of the seepage field; Defined as a variable Values ​​range from 1 to The operator that selects the maximum value from all the corresponding calculation result sets; Defined as the total number of miniature pore water pressure sensors; Defined as the number index of a miniature pore water pressure sensor; Defined as the current sampling time; Defined as the sampling time interval; Defined as the first The pore water pressure value measured by a miniature pore water pressure sensor at the current sampling time; Defined as the first The pore water pressure value measured by a miniature pore water pressure sensor at the previous sampling time; Defined as a very small positive number, to prevent the pore water pressure value from being too high during the initial stage of water injection. The result of the calculation diverges as it approaches zero.

[0112] The calculated instantaneous fluctuation rate of the seepage field is compared with a preset stability threshold. When the instantaneous fluctuation rate of the seepage field is less than the preset stability threshold, it is determined that a stable initial seepage field has been established inside the model test chamber unit 100. At this time, a pressure gradient decreasing from the upper constraint panel to the tunnel axis is formed inside the model test chamber unit 100. After determining that the initial seepage field is stable, the hydraulic loading module is kept running continuously to maintain a constant high-pressure hydraulic boundary inside the model test chamber unit 100.

[0113] S5. Under the established constant high-pressure hydraulic boundary and stable initial seepage field, the excavation unloading effect and blasting dynamic disturbance effect during the drilling and blasting construction process of the submarine tunnel are simulated. Through the coordinated work of the excavation simulation module and the vibration control module in the multi-source joint loading unit 300, the instability and water inrush disaster of the heterogeneous fault zone are induced.

[0114] The excavation advance of the prototype submarine tunnel project is mapped to the excavation simulation step distance inside the model test chamber unit 100. The length of a single excavation simulation step distance is set according to the established geometric similarity constant. Using the excavation simulation module, the surrounding rock background material, induced fracture zone simulation material, or fracture zone simulation material are removed step by step from the front constraint panel of the model test chamber unit 100 inwards according to the set excavation simulation step distance.

[0115] During each simulated excavation step, the water supply to the hydraulic loading module is temporarily blocked and the boundary water pressure is released. The horseshoe-shaped tunnel entrance pre-reserved interface on the front constraint panel is opened, and the surrounding rock or fault zone material within the current step is removed. The pre-reserved interface is then quickly closed, and the hydraulic loading module is restarted until the pore water pressure inside the model stabilizes again at 10 kPa. The excitation control module in the multi-source combined loading unit 300 is then activated. The excitation control module applies continuous periodic dynamic loads to the bottom of the model test chamber unit 100 to simulate the cyclic shearing effect of seismic waves on the fault zone. The output waveform of the excitation control module is set according to the following dynamic load control equation:

[0116] ;

[0117] In the formula, Defined as the excitation control module at time... Output acceleration value; Defined as the peak ground acceleration of the simulated seismic load, it is obtained by mapping the seismic intensity level (VI to IX) of the engineering prototype. Defined as the sine trigonometric function operator; Defined as the model loading frequency (set to 10Hz), it is calculated from the excellent cycle of the engineering prototype based on the time similarity constant; Defined as the duration of dynamic loading.

[0118] Throughout the application of transient dynamic loads, data from a 400Hz high-frequency monitoring and acquisition unit, a micro pore water pressure sensor, a micro earth pressure cell, and a multi-point displacement gauge were collected. The collected data was used to calculate the critical state identification coefficient for water inrush in the fault zone in real time. The formula for calculating the critical state identification coefficient for water inrush in the fault zone is shown below:

[0119] ;

[0120] ;

[0121] In the formula, Defined as the critical state identification coefficient for water inrush in the fault zone; Defined as the effective vertical stress at the key monitoring section of the fault zone, it is obtained by subtracting the pore water pressure measured by the micro pore water pressure sensor from the total stress measured by the micro earth pressure cell. Defined as the effective internal friction angle of the simulated material in the fracture zone; Defined as the effective cohesion of the simulated material in the fracture zone; Defined as the current static pore water pressure measured by a miniature pore water pressure sensor; Defined as the increase in excess pore water pressure induced by dynamic load; Defined as the pore pressure dynamic response coefficient; Defined as the peak value of the maximum dynamic stress transmitted to the monitoring point during dynamic loading.

[0122] The calculated critical state identification coefficient for water inrush in the fault zone is compared with a preset safety threshold (valued at 1.0). When the critical state identification coefficient for water inrush in the fault zone is less than the preset safety threshold, or when the monitoring and acquisition unit 400 detects a sudden surge in the flow rate of the inrush water, it is determined that a water inrush disaster has occurred inside the model test chamber unit 100, and the excavation simulation and dynamic loading operation are stopped, and the entire process test data is saved.

[0123] S6. In-depth data mining and feature analysis were performed on the entire experimental data recorded by monitoring and acquisition unit 400. Time series analysis was used to quantitatively characterize the instability evolution of heterogeneous fracture zones under the coupled action of seepage stress and deformation.

[0124] The time history curves of pore water pressure recorded by the micro pore water pressure sensor, the time history curves of contact stress recorded by the micro earth pressure cell, and the time history curves of surrounding rock displacement recorded by the multi-point displacement gauge are extracted from the database of the monitoring and acquisition unit 400. The extracted time history curves of pore water pressure, contact stress and surrounding rock displacement are then aligned with the time reference and subjected to noise filtering.

[0125] The multi-field coordinated abrupt change index of seepage stress-displacement is calculated. This index is used to quantify the system energy release rate and structural nonlinear response intensity of water-rich fault zones in submarine tunnels under dynamic disturbances. The formula for calculating the multi-field coordinated abrupt change index of seepage stress-displacement is shown below:

[0126] ;

[0127] In the formula, Defined as time The multi-field synergistic mutation index of seepage stress displacement; Defined as any sampling moment during the experiment; Defined as a time differential variable, it corresponds to the sampling time interval of the monitoring and acquisition unit 400 in numerical calculations; Defined as the weighting coefficient for the rate of change of pore water pressure; Defined as the initial hydrostatic pressure reference value; Defined as time The rate of change of pore water pressure over time; Defined as a weighting coefficient for the rate of change of contact stress; Defined as the initial reference value for surrounding rock stress; Defined as time The rate of change of contact stress over time; Defined as the weighting coefficient for the rate of change of surrounding rock displacement; Defined as the reference value for the maximum allowable deformation in tunnel design; Defined as time The rate of change of surrounding rock displacement over time; where .

[0128] Based on the calculated multi-field coordinated mutation index of seepage stress and displacement, the evolution process of water inrush in the fault zone is divided into three stages: incubation, development, and outbreak. By identifying the inflection points of the multi-field coordinated mutation index curve of seepage stress and displacement, the critical time node for the water inrush channel to be connected is determined. The catastrophic feature vector containing the critical time node, the maximum mutation index, and the corresponding peak values ​​of physical quantities is output, completing the entire process of the simulation test of water inrush in the water-rich fault zone of the submarine tunnel.

[0129] To verify the practical application effect of a simulation test system and method for water inrush in a water-rich fault zone of a submarine tunnel, this embodiment selects the F3 fault zone of a cross-sea tunnel project as the engineering prototype. The F3 fault zone is located in a seismic intensity zone of VI to IX. The F3 fault zone consists of fractured rock mass and induced fracture rock mass on both sides. The width of the F3 fault zone is 30m. The burial depth of the submarine tunnel prototype is 60m. The hydrostatic pressure of seawater that the submarine tunnel prototype withstands is approximately 0.6MPa.

[0130] The geometric similarity constant of model test chamber unit 100 is set to 100. The effective internal dimensions of the rigid model chamber are 1000mm × 1000mm × 1000mm. The geological structure layout module constructs a fault zone influence area with a total width of 300mm inside the rigid model chamber. The fault zone influence area includes a 100mm wide fracture zone area and two 100mm wide induced fracture zones on each side.

[0131] The similar material preparation unit 200 prepares a solid medium for filling. For the induced fracture zone region, the similar material preparation unit 200 prepares a simulated material for the induced fracture zone using iron concentrate, quartz sand, white cement, gypsum, and water in a mass ratio of 1:1.5:0.04:0.10:0.03. For the fractured zone region, the similar material preparation unit 200 prepares a simulated material for the fractured zone using a mass ratio of iron concentrate, quartz sand, white cement, gypsum, and water of 1:1.5:0.02:0.10:0.04.

[0132] The monitoring and acquisition unit 400's measuring point layout module embeds miniature pore water pressure sensors at vertical distances of 50mm, 100mm, and 150mm above the tunnel arch. A miniature earth pressure cell is also embedded at the center of the fractured zone within the same module. Furthermore, a multi-point displacement gauge is installed on the top of the rigid model box and inserted through the dynamic sealing flange to the tunnel arch position within the same module.

[0133] The water pressure loading module initiates the servo-controlled constant pressure water supply mechanism. The water pressure loading module applies a constant water pressure of 10 kPa to the inside of the rigid model box. The water pressure loading module maintains the 10 kPa pressure until the instantaneous fluctuation rate of the seepage field displayed by the monitoring and acquisition unit 400 is lower than 0.01.

[0134] The vibration control module sets the dynamic loading parameters. The loading frequency is set to 10Hz. Based on the IX-degree seismic intensity condition, the peak ground acceleration is set to 5.77 m / s². 2 The excitation control module generates an acceleration time history signal in the form of a standard sine wave.

[0135] The excavation simulation module performs step-by-step excavation operations. The single excavation step distance is set to 30mm. At the 5th excavation step (when the tunnel face enters the fractured zone), the excavation simulation module performs the following sequence of operations:

[0136] The input circuit is shut down and the boundary pressure is removed via the water pressure loading module. The operator opens the horseshoe-shaped tunnel opening pre-reserved interface on the front constraint panel and removes material to a depth of 30mm. The operator then closes the horseshoe-shaped tunnel opening pre-reserved interface, the water pressure loading module restarts and restores the hydrostatic pressure to 10kPa, and the vibration control module outputs a 10Hz simple harmonic vibration signal with a duration of 2 seconds (corresponding to 20 seconds for the engineering prototype).

[0137] During the output signal period of the vibration control module, the monitoring and acquisition unit 400 records the values ​​of the micro pore water pressure sensor, micro earth pressure cell, and multi-point displacement gauge at a sampling rate of 100Hz. The data processing module uses the recorded values ​​to calculate the critical state identification coefficient for water inrush in the fault zone and the multi-field coordinated abrupt change index of seepage stress and displacement.

Claims

1. A method for simulating water inrush in a water-rich fault zone of a submarine tunnel, characterized in that, Includes the following steps: Establish a physical quantity conversion benchmark between the prototype of the submarine tunnel project and the model test box unit (100). Use geometric similarity constants and density similarity constants to derive stress similarity constants, time similarity constants and permeability coefficient similarity constants to obtain a set of target values ​​for physical and mechanical parameters. Based on the set of target values ​​for physical and mechanical parameters, the mass ratio of the five-element material system is adjusted using the partitioning and proportioning module in the similar material preparation unit (200) to prepare and output simulated materials for induced fracture zones and simulated materials for fracture zones; The simulated material of the induced fracture zone and the simulated material of the fracture zone are filled into the model test chamber unit (100), and sensors are simultaneously embedded in the monitoring and acquisition unit (400) to form a consolidation physical model; A constant hydrostatic pressure boundary is constructed at the boundary of the consolidation physical model using a multi-source joint loading unit (300), and a stable initial seepage field is determined and established by calculating the instantaneous fluctuation rate of the seepage field. The excavation simulation module and vibration control module in the multi-source joint loading unit (300) are operated in a coordinated manner to perform step-by-step excavation and dynamic disturbance on the consolidated physical model until it is determined that a water inrush disaster has occurred inside the model test box unit (100), and the test data of the whole process are saved. The entire process test data is analyzed for features, and the multi-field synergistic mutation index of seepage stress and displacement is calculated. By identifying the inflection point of the multi-field synergistic mutation index curve of seepage stress and displacement, the critical time node for the water inrush channel to be connected is determined. The calculation method for the multi-field synergistic mutation index of seepage stress displacement is as follows: The pore water pressure time history curve, contact stress time history curve, and surrounding rock displacement time history curve are extracted, and the multi-field synergistic abrupt change index of seepage stress-displacement is calculated using the following formula: ； In the formula, For a moment The multi-field coordinated abrupt change index of seepage stress displacement; For any sampling moment during the experiment; As a time-differential variable, it corresponds to the sampling time interval of the monitoring and acquisition unit (400) in numerical calculation; This is the weighting coefficient for the rate of change of pore water pressure; This is the initial hydrostatic pressure reference value; For a moment The rate of change of pore water pressure over time; This is the weighting coefficient for the rate of change of contact stress; This is the initial reference value for surrounding rock stress; For a moment The rate of change of contact stress over time; This is the weighting coefficient for the rate of change of surrounding rock displacement; Reference value for the maximum allowable deformation in tunnel design; Defined as time The rate of change of surrounding rock displacement over time, of which .

2. The method for simulating water inrush in a water-rich fault zone of a submarine tunnel according to claim 1, characterized in that, The partitioning and proportioning module adjusts the mass ratio in the following manner: The basic skeleton density of the model material is controlled by the iron-sand ratio, which is defined as the ratio of the mass of iron concentrate to the mass of quartz sand in the five-element material system. The cementing strength and compressive modulus of the model material are controlled by the white cement content, wherein the white cement content is defined as the proportion of the mass of white cement to the total solid mass in the five-element material system. A second mass proportioning scheme is implemented for the simulated fracture zone material, which, compared to the first mass proportioning scheme implemented for the simulated fracture zone material, reduces the mass fraction of white cement and increases the mass fraction of water.

3. The method for simulating water inrush in a water-rich fault zone of a submarine tunnel according to claim 1, characterized in that, The excavation simulation module and the vibration control module work together in the following ways: When executing each excavation simulation step, open the horseshoe-shaped tunnel entrance reserved interface on the front constraint panel and remove the surrounding rock or fault zone material within the current step. Activate the excitation control module in the multi-source joint loading unit (300). The excitation control module applies continuous periodic dynamic loads to the bottom of the model test box unit (100) to simulate the cyclic shearing effect of seismic waves on the fault zone. The monitoring and acquisition unit (400) is used to calculate the critical state identification coefficient of water inrush in the fault zone in real time. When the critical state identification coefficient of water inrush in the fault zone is less than the preset safety threshold, it is determined that a water inrush disaster has occurred. The critical state identification coefficient for water inrush in the fracture zone is calculated using the following formula: ； ； In the formula, The critical state identification coefficient for water inrush in the fault zone; The effective vertical stress at the key monitoring section of the fault zone is obtained by subtracting the pore water pressure measured by the micro pore water pressure sensor from the total stress measured by the micro earth pressure cell. The effective internal friction angle of the material simulating the fracture zone; The effective cohesion of the material in the fracture zone is used to simulate the force of the material. The current static pore water pressure is measured by a miniature pore water pressure sensor. This refers to the increase in excess pore water pressure induced by dynamic loads. The pore pressure dynamic response coefficient; This represents the peak value of the maximum dynamic stress transmitted to the monitoring point during the dynamic loading process.

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