A multi-physical field test device for simulating synchronous grouting of a shield tail in shield construction

Abstract

This invention discloses a multi-physics field test device for simulating synchronous grouting at the tail of a tunnel boring machine (TBM), comprising: a visualization model box filled with soil, a shield shell embedded within the soil, and lining segments arranged in the gaps within the shield shell; a reconfigurable grouting system comprising multiple independently controlled grouting pipes evenly arranged circumferentially along the inner wall of the shield shell and extending axially from the front end to the tail end of the shield shell; a multi-dimensional synchronous monitoring system for synchronously collecting physical field data on grout diffusion, soil stress, segment stress, and surface settlement; a controllable propulsion system comprising a steel wire rope, one end of which is connected to the front end of the shield shell, and the other end of which is wound around a drum connected to a traction motor; and a thermal boundary condition simulation system comprising a heat exchange interlayer located in the bottom plate and / or side plate of the model box, the heat exchange interlayer being connected to an external constant temperature circulation system to provide a controllable initial temperature field for the soil.

Description

Technical Field

[0001] This invention relates to the field of tunnel construction technology, specifically to a multi-physics field test device for simulating synchronous grouting at the tail of a shield tunnel. Background Technology

[0002] In shield tunnel construction, synchronous grouting at the shield tail is a core process used to fill the gap between the shield shell and the segment lining, control surface settlement, and prevent groundwater intrusion. However, this process involves complex coupling effects between grout, soil, and segment structure (multi-physics field), and the properties of the grout change over time, resulting in significant time-varying mechanical behavior.

[0003] The existing model testing devices mainly suffer from the following bottlenecks: 1. Single monitoring dimension: Most monitoring focuses only on a single physical field such as ground settlement or grouting pressure, and cannot simultaneously capture multi-field data in the complete coupling chain of "grout diffusion-soil response-segment stress", which makes it impossible to reveal its internal interaction mechanism; 2. Rigid grouting pattern: The grouting hole position and number are fixed, lacking the ability to simulate reconfigurable grouting strategies, and unable to actively study the influence of different grouting processes (such as the number of holes, position, and timing) on ​​the grout flow state and structural stress; 3. Neglecting timeliness: Existing equipment generally does not consider the key time-varying process of slurry solidification and hardening, and cannot simulate and study the evolution of slurry properties over time on the long-term stress of the tunnel segments and the formation displacement. 4. Weak visualization capabilities: It is difficult to directly observe the diffusion morphology and filling process of the slurry in the voids, keeping the research in a "black box" stage and hindering a deeper understanding of the flow mechanism.

[0004] 5. Lack of proactive thermal boundary control capability: Existing devices can only conduct 'insulation' or 'natural heat dissipation' tests at laboratory room temperature, which leads to serious deviations between the measured key parameters such as slurry diffusion radius and buoyancy dissipation time on the segments and actual extreme working conditions.

[0005] Therefore, there is an urgent need for an experimental device that can comprehensively simulate, monitor and analyze the multi-physics coupling effect throughout the entire process of synchronous grouting, so as to provide accurate data support for theoretical research and engineering practice. Summary of the Invention

[0006] To address the aforementioned shortcomings of existing technologies, this invention provides a multi-physics field test device for simulating synchronous grouting at the tail of a tunnel boring machine, which solves the problems of insufficient monitoring dimensions, inadequate timeliness simulation, poor flexibility, and lack of visualization in existing tunnel grouting test devices.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A multiphysics test device for simulating synchronous grouting at the tail of a tunnel boring machine is provided, comprising: a visualization model box with four transparent observation panels on its four sides; the visualization model box is filled with soil, a shield shell is embedded in the soil, and lining segments are installed in the gaps inside the shield shell. The reconfigurable grouting system includes multiple independently controlled grouting pipes, which are evenly arranged circumferentially along the inner wall of the shield and extend axially from the front end to the rear end of the shield; all the grouting pipes are connected to the grouting pump via grouting hoses. A multi-dimensional synchronous monitoring system is used to simultaneously collect physical field data on slurry diffusion, soil stress, segment stress, and surface settlement. The controllable propulsion system includes a steel wire rope, one end of which is connected to the front end of the shield, and the other end of which is wound around a drum, which is connected to a traction motor drive. The thermal boundary condition simulation system includes a heat exchange interlayer located in the bottom plate and / or side plate of the model box. The heat exchange interlayer is connected to an external constant temperature circulation system to provide a controllable initial temperature field for the soil.

[0008] Furthermore, the multi-dimensional synchronous monitoring system includes several earth pressure cells arranged in the soil, several strain gauges installed on the outer surface of the lining segments, a dial gauge set on the soil surface for observing soil settlement, and a high-speed camera for recording the grout flow process.

[0009] Furthermore, a connecting plate is set at the front end of the shield shell, and a high-speed camera is located in the middle of the rear end of the shield shell. The high-speed camera is fixedly connected to the connecting plate via a connecting rod, and a steel wire rope is fixedly connected to the connecting plate.

[0010] Furthermore, the multi-dimensional synchronous monitoring system also includes a temperature field monitoring system, which includes several temperature sensors arranged in the slurry area, soil area and segment area. Several temperature sensors, earth pressure cells, strain gauges and dial gauges are electrically connected to the control terminal through a multi-channel data acquisition instrument.

[0011] Furthermore, several temperature sensors located in the segment area are evenly arranged on the outer surface of the lining segments in the axial and circumferential directions. Several temperature sensors located in the soil area are pre-embedded in the soil, forming a three-dimensional temperature measurement grid centered on the shield and measuring the soil temperature at different depths and distances from the shield. Several temperature sensors located in the grout area are arranged in the soil on the outer surface of the shield and are evenly arranged on the outer surface of the shield in the axial and circumferential directions.

[0012] Furthermore, the heat exchange jacket has built-in coils or heat-conducting plates, and the external constant temperature circulation system is a high-precision liquid bath system, maintaining the temperature of the circulating medium from -10°C to 50°C.

[0013] Furthermore, each grouting pipe is equipped with an independently controlled grout stop valve, allowing for flexible combinations of the number, location, and timing of grouting holes by opening and closing different grouting pipes.

[0014] Furthermore, the observation panel is made of high-strength acrylic sheet, and the front side of the visualization model box has a circular opening for the shield shell to pass through. Several wiring holes are also provided on the front and rear sides of the visualization model box.

[0015] Furthermore, grout-stopping rings are installed at the circular opening and at the gap between the shield tail end and the lining segments.

[0016] The beneficial effects of this invention are as follows: 1. This scheme achieves synchronous acquisition of grout diffusion, soil stress, segment stress, and surface settlement through an integrated and synchronized multi-dimensional synchronous monitoring system. In the physical model, it realizes synchronous, real-time, and accurate capture and correlation analysis of the three major physical fields: grout diffusion field, soil stress field, and segment stress field. This allows researchers to directly observe and analyze the entire chain dynamic process of "grouting driving soil deformation - soil deformation feedback acting on the segment". It realizes real-time synchronous monitoring and visualization analysis of the full coupling effect of "grout-soil-structure", revealing the deep interaction mechanism.

[0017] 2. This scheme utilizes multiple independently controllable and flexibly detachable grouting pipes, enabling operators to implement different grouting strategies, such as symmetrical / asymmetrical grouting, single-hole / multi-hole grouting, and intermittent / continuous grouting. This allows for a systematic study of the influence mechanism of grouting process parameters on grout flow pattern, filling uniformity, segment bias, and buoyancy. Consequently, grouting is transformed from an empirical operation into a quantitatively researchable and optimizable scientific process, providing a direct theoretical basis and process verification platform for intelligent grouting and precision construction.

[0018] 3. The physical model of this scheme has the ability to study the time-varying laws of stress on tunnel segments and stratum displacement throughout the entire cycle from grout injection, flow, initial setting to complete hardening. This provides data support for the study of the change of load transfer path and the dissipation law of long-term buoyancy during the solidification process of tail grout, which is of great engineering significance for predicting and controlling the long-term settlement and stability of tunnels.

[0019] 4. The purpose of setting up the thermal boundary condition simulation system in this scheme is to scientifically simulate the thermal inertia of an infinitely large stratum. By actively presetting stable and uniform thermal boundary conditions for the test soil, the thermal interaction process between the grout and the real stratum is reproduced in the physical model, thereby realizing the study of extreme working conditions such as early freezing damage of tunnel grouting bodies in cold regions and the risk of rapid setting of grout in geothermal-rich areas.

[0020] 5. This scheme achieves active control of initial thermal conditions through the linkage of an integrated temperature field monitoring system and a thermal boundary control system, thereby effectively isolating and quantifying the influence of "heat" on mechanical behavior, and providing direct theoretical and experimental basis for the design and construction process of differentiated and precise grouting materials for different regional climates and geological conditions. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly described below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. The above and other objects, features, and advantages of the present invention will become clearer through the accompanying drawings. The same reference numerals indicate the same parts in all the drawings. The drawings are not intentionally drawn to scale to actual dimensions; the focus is on illustrating the main points of the invention.

[0022] Figure 1 A schematic diagram of a multiphysics field test device for simulating synchronous grouting at the tail of a tunnel boring machine.

[0023] Figure 2 This is a cross-sectional view of the visualization model box.

[0024] Figure 3 This is a cross-sectional view of the shield.

[0025] Among them, 1. Visual model box, 11. Shield shell, 12. Lining segment, 13. Circular opening, 14. Wiring hole, 15. Grout stop ring, 21. Grouting pipe, 22. Grouting hose, 23. Grout stop valve, 24. Grouting pump, 31. Earth pressure cell, 32. Strain gauge, 33. Dial gauge, 34. High-speed camera, 35. Connecting rod, 36. Connecting plate, 37. Multi-channel data acquisition instrument, 38. Computer, 39. Support, 310. Temperature sensor, 41. Steel wire rope, 42. Traction motor, 51. Thermal circulation pump, 52. Thermal pipeline. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0027] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0028] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0029] Furthermore, the terms "first," "second," etc., are used only to distinguish descriptions and should not be interpreted as indicating or implying relative importance.

[0030] In shield tunnel construction, synchronous grouting behind the shield tail wall is a crucial construction procedure. Its main function is to simultaneously fill the gaps between the lining structure and the surrounding soil during the tunnel boring machine's excavation and segment assembly, ensuring that the pressure from the surrounding soil is evenly applied to the newly assembled lining ring, thereby achieving early stability of the lining structure. Synchronous grouting behind the shield tail wall plays a vital role in controlling tunnel surface settlement and preventing groundwater leakage from the surrounding soil into the segments. Current technology struggles to fully simulate phenomena such as grout diffusion behind the wall and segment uplift under synchronous grouting.

[0031] During synchronous grouting, interactions inevitably occur between the tunnel segments and the grout, and between the grout and the soil. Due to the time-dependent solidification of the grout, these interactions change as the grout solidifies. Furthermore, grout rheology is influenced by numerous factors, including geological conditions, grouting pressure, grout properties, and groundwater pressure. Therefore, studying the segment-grout-soil interaction solely through theoretical analysis is somewhat one-sided and cannot prove its accuracy and reliability. Thus, conducting model tests on the interaction between the strata and tunnel segment structure under synchronous grouting in shield tunnel construction is of great significance for the safety and stability of shield tunnel construction.

[0032] After the grout is injected, its hydration heat release process interacts violently with the geothermal field. The grout's solidification rate, rheological properties, and the strength of the final solidified body are all decisively affected by this heat exchange process. All existing test devices treat the model box as an adiabatic environment, completely ignoring the key physical process of "geothermal-grout heat interaction." This leads to a serious disconnect between test results and actual engineering conditions, making it impossible to predict the grouting effect and long-term safety under specific thermal environments (such as winter construction or traversing geothermal anomaly zones).

[0033] like Figures 1 to 3 As shown, the multiphysics test device for simulating synchronous grouting at the tail of a tunnel boring machine includes: The visualization model box 1 has four transparent observation panels on its four sides. The visualization model box 1 is filled with soil, and a shield shell 11 is embedded in the soil. Lining segments 12 are installed in the gaps inside the shield shell 11. The observation panels are made of high-strength acrylic plates. A circular opening 13 is opened on the front side of the visualization model box 1 for the shield shell 11 to pass through. Several wiring holes 14 are opened on the front and rear sides of the visualization model box 1. Grout stop rings 15 are installed at the circular opening 13 and at the gap between the tail end of the shield shell 11 and the lining segments 12. This arrangement not only provides a window for direct observation of the macroscopic diffusion morphology of grout, but more importantly, it lays the foundation for future application of transparent soil technology and particle image velocimetry for microscopic flow field analysis, realizing the connection of multi-physics field observation from macroscopic to microscopic.

[0034] In practice, the high-strength acrylic sheet is 10mm thick, the main body of the visualization model box 1 is welded from steel, and the bottom plate is welded from a 20mm thick steel plate. The shield shell 11 is a cylindrical structure made of steel, with an outer diameter the same as the size of the circular opening 13 and a length greater than the front-to-back distance of the visualization model box 1. The lining segment 12 is made of acrylic tubes and simulates the actual shield segment structure according to a certain similarity ratio. The lining segment 12 is fixed to the rear panel of the visualization model box 1 by two fixed components, so that the gap between the lining segment 12 and the shield shell 11 is uniform and not easy to shift, so that the gap in the middle is used for grouting. Holes are made on the lining segment 12, with 8 holes per section, for a total of three sections, to facilitate the subsequent installation of strain gauges 32. In addition, in order to better fit the actual project, the lining segment 12 can be replaced with a plaster model as needed, which is more research-oriented. The shield tail gap is equal to the difference between the inner diameter of the shield shell 11 and the outer diameter of the lining segment 12.

[0035] A reconfigurable grouting system includes multiple independently controlled grouting pipes 21, which are evenly arranged circumferentially along the inner wall of the shield 11 and extend axially from the front end to the rear end of the shield 11, with the grouting port of each grouting pipe 21 facing the tail gap. The multiple grouting pipes 21 are connected to a grouting pump 24 via quick-release couplings, grouting hoses 22, and grout stop valves 23. Each grouting pipe 21 is equipped with an independently controlled grout stop valve 23 to control the opening, closing, and flow rate of each grouting pipe 21. The system allows for flexible combinations of the number, location, and timing of grouting holes by opening and closing different grouting pipes 21. For example, operators can flexibly simulate various grouting modes such as single-hole, double-hole, four-hole, symmetrical, and asymmetrical grouting. This system overcomes the limitations of fixed-hole grouting, thereby enabling the study of the influence of grouting process parameters on the grouting effect.

[0036] The multi-dimensional synchronous monitoring system includes several earth pressure cells 31 arranged in the soil, several strain gauges 32 installed on the outer surface of the lining segment 12, a dial gauge 33 set on the soil surface via a support 39 for observing soil settlement, and a high-speed camera 34 installed inside the lining segment 12. It is used to synchronously collect physical field data on grout diffusion, soil stress, segment stress, and surface settlement. Specifically, it includes the grout diffusion field: recording the grout flow process via the high-speed camera 34; and the soil stress field: monitoring different locations and depths via the pre-embedded earth pressure cells 31. Earth pressure variation; segment stress field: grouting pressure and radial pressure provided by soil are directly measured by several strain gauges 32; surface displacement field: soil surface settlement is monitored by dial gauge 33 or laser displacement sensor; all sensor data are synchronously and in real time collected by multi-channel acquisition instrument, providing a complete and time-varying data chain for constructing the coupling relationship model of "grout-soil-structure"; a connecting plate 36 is set at the front end of the shield shell 11, and a high-speed camera 34 is located in the middle of the rear end of the shield shell 11, and the high-speed camera 34 is fixedly connected to the connecting plate 36 through a connecting rod 35.

[0037] The multi-dimensional synchronous monitoring system also includes a temperature field monitoring system, which comprises several temperature sensors 310 arranged in the grout area, soil area, and segment area. The temperature sensors 310 use T-type thermocouples or PT100 platinum resistance thermometers, which are characterized by fast response, high accuracy (±0.1°C), small size, and corrosion resistance, making them suitable for embedding in soil and immersion in grout. Several temperature sensors 310, earth pressure cells 31, strain gauges 32, and dial gauges 33 are electrically connected to the control terminal via a multi-channel data acquisition instrument 37. In specific implementation, for the grout area: temperature sensors 310 are arranged on the shield shell... Within the soil of the outer surface of the shield 11, temperature sensors 310 are uniformly arranged axially and circumferentially on the outer surface of the shield 11. A temperature measurement section is arranged every 10-15 cm along the tunnel axis. Each section has four temperature sensors 310 evenly arranged along the main path of grout diffusion, directly monitoring the heat of hydration and temperature diffusion process after grout injection. In the soil area, temperature sensors 310 are pre-embedded in the soil of the visualization model box 1, forming a three-dimensional temperature measurement grid centered on the shield 11 and measuring soil temperatures at different depths and distances from the shield 11, to capture the attenuation of the thermal gradient, for example, at different horizontal distances from the tunnel axis (e.g., 0.3 m). Temperature sensors 310 are installed at depths of 0.6m, 0.9m and different depths (such as shallow, medium and deep layers) to monitor the ground temperature gradient and the propagation range and attenuation law of grout thermal disturbance; in the pipe segment area, temperature sensors 310 are installed on the outer surface of the lining pipe segment 12 in the axial and circumferential directions (such as the arch top, arch waist and arch bottom) to monitor the temperature change of the lining pipe segment 12 itself and the thermal effects it is subjected to.

[0038] All temperature sensors 310, earth pressure cells 31, strain gauges 32, and dial gauges 33 are connected to a multi-channel data acquisition instrument 37 via shielded cables. Data is collected in strict synchronization with data from earth pressure, strain, and displacement sensors. The sampling frequency can be set as needed (e.g., 1-100Hz). The data is transmitted in real time to host computer software (e.g., LabVIEW or a custom platform) for display, recording, and fusion analysis, and a complete "force-heat-fluid" time-varying database is formed on computer 38.

[0039] The controllable propulsion system includes a steel wire rope 41, one end of which is fixedly connected to the connecting plate 36 at the front end of the shield shell 11, and the other end of which is wound around a drum. The drum is connected to the traction motor 41 for transmission. In specific implementation, a variable frequency motor can be used to drive the steel wire rope 41 to pull the shield shell 11, so as to realize stepless speed regulation of the propulsion speed. This not only simulates the actual construction conditions, but more importantly, it ensures the stability and repeatability of the propulsion process in the long-term test of studying the time-varying process.

[0040] The thermal boundary condition simulation system includes a heat exchange interlayer located within the bottom plate and / or side plates of the model box. This interlayer is connected to an external isothermal circulation system to provide a controllable initial temperature field for the soil. In practice, the heat exchange interlayer contains internal thermal pipes 52, and the external isothermal circulation system is a high-precision liquid bath system. A thermal circulation pump 51 drives the circulating medium to circulate and exchange heat within the thermal pipes 52 to achieve an isothermal effect. The temperature of the circulating medium is maintained between -10°C and 50°C, with the circulating medium used in low-temperature conditions... Ethylene glycol and silicone oil are used at high temperatures. For example, this scheme can simulate strata in cold regions at 5°C, strata in normal temperatures at 15°C, or strata in hot regions at 25°C, thus providing a stable, uniform, and settable initial thermal boundary condition for the entire test soil. This simulates the thermal environment of an infinitely large stratum in which a real tunnel is located. By actively presetting thermal boundary conditions for the soil, this scheme reproduces the thermal interaction process between the grout and the real stratum in the physical model. This makes it possible to study extreme conditions such as early freezing damage to grouting bodies in cold regions and the risk of rapid setting of grout in geothermal-rich areas.

[0041] Before the experiment began, the high-precision liquid bath system was started to keep the soil in the visualization model box 1 at a preset temperature (usually 12-24 hours to reach thermal equilibrium) to simulate the target stratum environment; the controllable propulsion system and the reconfigurable grouting system were started, and the grout (with its own initial temperature) was injected into the soil with a specific "ground temperature"; the multi-dimensional synchronous monitoring system synchronously captured: (1) thermal field: how the heat of the grout diffuses to the surrounding "cold" stratum (or "hot" stratum), and how the temperature field evolves in time and space; (2) force field: how the solidification rate of the grout changes under different thermal boundaries, and how it affects the time-varying curves of the buoyancy and lateral pressure of the pipe segment; (3) flow field: how the viscosity of the grout changes due to temperature changes, thereby affecting its diffusion radius and filling shape; throughout the process, the multi-dimensional synchronous monitoring system worked synchronously, recording the data changes of all multi-physics fields in the entire time-varying process from grout flow (liquid state) to hardening (solid state), thereby revealing the complete coupling mechanism.

[0042] During the experiment, soil materials meeting the experimental similarity ratio requirements were filled into the visualization model box 1 to prepare the geological environment surrounding the tunnel. A controllable propulsion system was activated to move the shield shell 11 forward at a set speed to simulate shield tunneling. Simultaneously, a reconfigurable grouting system was activated to inject grout into the shield tail gap according to the set grouting mode (number of holes, location, pressure, flow rate, and grout ratio). The grout diffusion pattern was directly observed through a transparent panel. A multi-dimensional synchronous monitoring system recorded in real time parameters such as surface settlement, changes in soil internal pressure (earth pressure cell), segment stress state (segment sensors), and grouting pressure. The effects of changing tunneling speed, grouting parameters, grouting mode, and geological conditions on grout diffusion, segment stress, and surface settlement were studied, with particular consideration given to the long-term effects of grout solidification time.

[0043] In summary, this scheme constructs a comprehensive test platform capable of reproducing the coupling effects of multiple physics fields. Through a reconfigurable grouting system, it enables flexible simulation and active optimization of grouting strategies. It integrates advanced monitoring technologies to record the complete time-varying process from grout injection to hardening and stabilization. Ultimately, it reveals the intrinsic mechanism of synchronous grouting, providing theoretical basis and practical guidance for intelligent construction and safety control of shield tunnels. It breaks through the "adiabatic assumption" of traditional tests and creates a test device that can actively simulate and control the thermal boundary conditions of the strata surrounding the tunnel.

[0044] Although the specific embodiments of the invention have been described in detail with reference to the accompanying drawings, this should not be construed as limiting the scope of protection of this patent; various modifications and variations that can be made by a person skilled in the art without inventive effort within the scope described in the claims are still within the scope of protection of this patent.

Claims

1. A multiphysics field test device for simulating synchronous grouting at the tail of a tunnel boring machine, characterized in that, include: The visualization model box has four transparent observation panels on all four sides; the visualization model box is filled with soil, and a shield shell is buried in the soil, with lining segments installed in the gaps inside the shield shell. A reconfigurable grouting system includes multiple independently controlled grouting pipes, which are evenly arranged circumferentially along the inner wall of the shield and extend axially from the front end to the rear end of the shield; all of the grouting pipes are connected to a grouting pump via grouting hoses. A multi-dimensional synchronous monitoring system is used to simultaneously collect physical field data on slurry diffusion, soil stress, segment stress, and surface settlement. A controllable propulsion system includes a steel wire rope, one end of which is connected to the front end of the shield shell, and the other end of which is wound around a drum, the drum being connected to a traction motor drive. The thermal boundary condition simulation system includes a heat exchange interlayer located in the bottom plate and / or side plate of the model box. The heat exchange interlayer is connected to an external constant temperature circulation system to provide a controllable initial temperature field for the soil.

2. The multiphysics field test device for simulating synchronous grouting at the tail of a tunnel boring machine as described in claim 1, characterized in that, The multi-dimensional synchronous monitoring system includes several earth pressure cells arranged in the soil, several strain gauges installed on the outer surface of the lining segments, a dial gauge set on the soil surface for observing soil settlement, and a high-speed camera for recording the grout flow process.

3. The multiphysics field test device for simulating synchronous grouting at the tail of a tunnel boring machine as described in claim 2, characterized in that, A connecting plate is provided at the front end of the shield shell, the high-speed camera is located in the middle of the rear end of the shield shell, and the high-speed camera is fixedly connected to the connecting plate via a connecting rod, and the steel wire rope is fixedly connected to the connecting plate.

4. The multiphysics field test device for simulating synchronous grouting at the tail of a tunnel boring machine as described in claim 2, characterized in that, The multi-dimensional synchronous monitoring system also includes a temperature field monitoring system, which includes several temperature sensors arranged in the slurry area, soil area and segment area. The temperature sensors, earth pressure cells, strain gauges and dial gauges are electrically connected to the control terminal through a multi-channel data acquisition instrument.

5. The multiphysics field test device for simulating synchronous grouting at the tail of a tunnel boring machine as described in claim 4, characterized in that, Several temperature sensors located in the segment area are evenly arranged on the outer surface of the lining segment in the axial and circumferential directions. Several temperature sensors located in the soil area are pre-embedded in the soil and form a three-dimensional temperature measurement grid centered on the shield and measuring the soil temperature at different depths and distances from the shield. Several temperature sensors located in the grout area are arranged in the soil on the outer surface of the shield and are evenly arranged on the outer surface of the shield in the axial and circumferential directions.

6. The multiphysics field test device for simulating synchronous grouting at the tail of a tunnel boring machine as described in claim 1, characterized in that, The heat exchange jacket has a built-in coil or heat-conducting plate, and the external constant temperature circulation system is a high-precision liquid bath system, which maintains the temperature of the circulating medium from -10°C to 50°C.

7. The multiphysics field test device for simulating synchronous grouting at the tail of a tunnel boring machine as described in claim 1, characterized in that, Each of the grouting pipes is equipped with an independently controlled grout stop valve, allowing for flexible combinations of the number, location, and timing of grouting holes by opening and closing different grouting pipes.

8. The multiphysics field test device for simulating synchronous grouting at the tail of a tunnel boring machine as described in claim 1, characterized in that, The observation panel is made of high-strength acrylic sheet. The front side of the visualization model box has a circular opening for the shield shell to pass through. The front and rear sides of the visualization model box also have several wiring holes.

9. The multiphysics field test device for simulating synchronous grouting at the tail of a tunnel boring machine as described in claim 8, characterized in that, Grout-stopping rings are installed at the circular opening and at the gap between the tail end of the shield and the lining segments.

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