Tunnel hidden defect simulation detection system

Abstract

The invention provides a tunnel hidden defect simulation detection system, and relates to the technical field of tunnel detection. The method comprises a lining structure, a hidden defect simulation assembly, a radar assembly and a signal processing assembly. The lining structure comprises reinforcing meshes with different mesh sizes and internal defect simulation components; the reinforcing meshes with different mesh sizes are used for simulating the reinforcing meshes under different conditions, and the internal defect simulation component is used for simulating a lining structure under different internal defects; the hidden defect simulation assembly comprises a frame, a hidden defect simulation component and surrounding rock; the radar assembly is used for transmitting and receiving electromagnetic waves in a preset frequency range. The signal processing assembly is used for processing radar echo signals received by the radar, determining radar signal characteristics under the conditions of internal defects of different lining structures and tunnel hidden defects according to the radar echo signals, and constructing a hidden defect simulation detection database. According to the invention, tunnel simulation detection under different working conditions can be realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of tunnel detection, in particular to a tunnel hidden defect simulation detection system. BACKGROUND

[0002] Most of the tunnel hidden defects are due to non-standard construction process, structural defects and ineffective detection and treatment of adverse geology. With the extension of tunnel service time, under the coupling action of stratum pressure, structure dead weight, earthquake, groundwater scouring corrosion and other sources, the contact surface between the lining and the surrounding stratum is further stripped, and even large-scale voids and karst caves and other diseases occur. If the hidden defects of the tunnel structure cannot be detected and treated in time, it will cause immeasurable loss and harm to personnel and property.

[0003] The test platform for detecting tunnel hidden defects by using the commonly used ground penetrating radar has problems such as difficulty in replacing related components, and is inconvenient for simulating and detecting tunnel hidden defects under different working conditions. SUMMARY

[0004] The tunnel hidden defect simulation detection system provided by the embodiments of the present application solves the problem of inconvenient tunnel simulation detection under different conditions.

[0005] In a first aspect, the embodiments of the present application provide a tunnel hidden defect simulation detection system, comprising:

[0006] a lining structure, a hidden defect simulation assembly, a radar assembly and a signal processing assembly;

[0007] The lining structure comprises a steel mesh with different grid sizes and an internal defect simulation component. The steel mesh with different grid sizes is used to simulate the steel mesh under different conditions, and the internal defect simulation component is used to simulate the lining structure under different internal defects.

[0008] The hidden defect simulation assembly is located on one side of the lining structure. The hidden defect simulation assembly comprises a frame, a hidden defect simulation component and surrounding rock. The frame and the lining structure form a cavity therebetween, and the surrounding rock with different dielectric constants is arranged in the cavity to simulate the geological properties under different conditions. The hidden defect simulation component is located in the surrounding rock, and is used to simulate hidden defects.

[0009] The radar assembly is used to emit and receive electromagnetic waves with a preset frequency range.

[0010] The signal processing assembly is used to process the radar echo signal received by the radar, determine the radar signal characteristics under the conditions of internal defects of different lining structures and tunnel hidden defects according to the radar echo signal, and construct a hidden defect simulation detection database.

[0011] In a possible implementation, the surrounding rock with different dielectric constants corresponds to different particle size combinations of fine sand and sandstone, layering characteristics and water content of fine sand.

[0012] In a possible implementation, the frame comprises a concrete plate or a wooden plate.

[0013] The frame is selected according to the surrounding rock with different dielectric constants.

[0014] In a possible implementation, the concealed defect simulation assembly further comprises a reinforcing member.

[0015] The reinforcing member is an insulating member arranged at the outer periphery of the frame and used for fixing the frame.

[0016] In a possible implementation, the concealed defect simulation assembly comprises a cavity simulation member and a water film injection member, and the concealed defect comprises a surrounding rock cavity and a surrounding rock karst cave.

[0017] The cavity simulation member with different positions, sizes and shapes simulates the surrounding rock cavity with different positions and shapes, and the water film injection member with different shapes simulates the surrounding rock karst cave with different shapes; the cavity simulation member is an expanded polystyrene board.

[0018] In a possible implementation, the shape of the cavity simulation member comprises a spherical shape, an ellipsoidal shape, a long strip shape and an irregular shape.

[0019] In a possible implementation, the internal defect simulation assembly comprises a gas injection part, a movable part and a water injection part; and the internal defect comprises a gas-containing cavity, a water-containing cavity and an interlayer contact not dense.

[0020] The gas injection part, the movable part and the water injection part are arranged at different positions in the lining structure based on a lining pouring process; the gas injection part is used for simulating the gas-containing cavity under different conditions.

[0021] The water injection part is used for simulating the water-containing cavity under different conditions.

[0022] The movable part is used for simulating the interlayer contact not dense under different conditions.

[0023] In a possible implementation, the internal defect further comprises a lining pouring quality problem and a lining structure thickness problem.

[0024] Different lining pouring defects in the lining structure simulate the lining pouring quality problem under different conditions.

[0025] Different lining pouring thicknesses in the lining structure simulate the lining structure thickness problem under different conditions.

[0026] In a possible implementation, the internal defect simulation component further comprises a steel bar corrosion simulation component for simulating steel bar corrosion.

[0027] The steel bar corrosion simulation component simulates steel bar corrosion under different conditions by using corrosion media with different injection amounts and different reaction times.

[0028] In a possible implementation, the lining structure type comprises a lining structure of a drill-and-blast tunnel and a lining structure of a shield tunnel.

[0029] The lining structure of the drill-and-blast tunnel comprises an arch, primary support, waterproof board, secondary lining and reinforcing component, the arch is connected with the primary support, the primary support is connected with the waterproof board, the waterproof board is connected with the secondary lining, and the secondary lining is connected with the reinforcing component; and the lining structure of the shield tunnel comprises a segment, bolt and grouting layer, the segment is connected with the bolt, and the segment is connected with the grouting layer.

[0030] In the embodiment, the grid size of the steel bar mesh of the lining structure is adjustable, and the dielectric constant of the surrounding rock is adjustable, so that the system can simulate various tunnel scenes and defects and has strong adaptability. By simulating different surrounding rock characteristics, the radar assembly obtains a return signal and determines the defect characteristics through signal processing, to realize high-precision detection. The system components are based on explicit parameter setting and adjustment, so that the simulation scene can be repeatedly built to ensure the repeatability and consistency of the results. Through a large number of simulation experiments, a mapping relationship between hidden defects and radar signal characteristics is established, to provide a scientific basis for ground penetrating radar detection. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 is a schematic diagram of a tunnel hidden defect simulation and detection system provided by the embodiment of the present application;

[0032] Figure 2 is a schematic diagram of a tunnel hidden defect simulation and detection test method provided by the embodiment of the present application;

[0033] Figure 3 is a schematic diagram of a B-Scan image variation rule of a mapping relationship between a ground penetrating radar detection result and a surrounding rock internal cavity provided by the embodiment of the present application;

[0034] Figure 4 is a schematic diagram of an A-Scan signal variation rule of a mapping relationship between a ground penetrating radar detection result and a surrounding rock internal cavity provided by the embodiment of the present application. DETAILED DESCRIPTION

[0035] The embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0036] The test platform commonly used for detecting tunnel hidden defects by ground penetrating radar has problems of single defect, fixed depth, uncontrolled surrounding rock medium properties, and difficult replacement of lining, and thus cannot be applied to analysis of variation rules of different depths and different forms of tunnel hidden defects in radar images, thereby limiting the application range of this type of model test.

[0037] Therefore, based on this, the present application aims at the problem of widely distributed and various forms of hidden defects inside and behind the tunnel lining structure under the condition of complex tunnel environment and the range of surrounding rock dielectric constant, and improves the compatibility of the test platform and the reliability of the test results through the following measures: precise prefabricated components, modular test device, adjustment of surrounding rock dielectric constant, reasonable arrangement of hidden defect position and form, etc.

[0038] Figure 1 The schematic diagram of the tunnel hidden defect simulation detection system provided by the embodiment of the present application is shown in Figure 1 As shown in the schematic diagram, the tunnel hidden defect simulation detection system comprises:

[0039] a lining structure 1, a hidden defect simulation assembly 2, a radar assembly, and a signal processing assembly.

[0040] The lining structure comprises steel meshes of different grid sizes and internal defect simulation components; the steel meshes of different grid sizes are used to simulate steel meshes under different conditions, and the internal defect simulation components are used to simulate lining structures under different internal defects.

[0041] The hidden defect simulation assembly 2 is located on one side of the lining structure 1, and comprises a frame 21, a hidden defect simulation component 23, and surrounding rock 22; the frame 21 and the lining structure 1 form a cavity therebetween, and the surrounding rock 22 of different dielectric constants is arranged in the cavity to simulate geological properties under different conditions; the hidden defect simulation component 23 is located in the surrounding rock 22, and is used to simulate hidden defects.

[0042] The radar assembly is used to emit and receive electromagnetic waves of a preset frequency range.

[0043] The signal processing assembly is used to process radar echo signals received by the radar, determine radar signal characteristics under the conditions of internal defects of different lining structures and tunnel hidden defects according to the radar echo signals, and construct a hidden defect simulation detection database.

[0044] Specifically, the components in the present application can be detachably arranged. The lining structure comprises steel meshes of different grid sizes and internal defect simulation components. The steel meshes of different grid sizes can simulate the conditions of the steel meshes under various construction conditions, and the internal defect simulation components are used to simulate various defects that may occur inside the lining structure. The concealed defect simulation assembly is located on one side of the lining structure and is composed of a frame, a concealed defect simulation component and surrounding rock. The frame forms a cavity with the lining structure, and the cavity is filled with surrounding rock of different dielectric constants to simulate different geological properties. The concealed defect simulation component is placed in the surrounding rock to simulate the concealed defects that may occur in the actual tunnel. The main function of the radar assembly is to transmit and receive electromagnetic waves in a specific frequency range. These electromagnetic waves will produce reflections and form radar echo signals when they encounter different media inside the tunnel, such as steel meshes, lining structures, surrounding rocks and defects. The signal processing assembly processes the echo signals received by the radar, determines the corresponding radar signal characteristics of different internal defects of the lining structure and the concealed defects of the tunnel by analyzing these signals, and constructs a concealed defect simulation detection database to provide data support and technical basis for subsequent detection and analysis.

[0045] By adjusting the grid size of the steel mesh, the dielectric constant of the surrounding rock, the position, size and shape of the concealed defect simulation component and other parameters, various different tunnel scenarios and defect conditions can be simulated. With the detachable and modular component design, it is convenient to assemble and adjust the system according to different test requirements, and to realize the simulation and detection of concealed defects in tunnels under different working conditions. With the help of ground penetrating radar technology, the radar assembly transmits electromagnetic waves. These electromagnetic waves propagate in the tunnel structure and produce reflections when they encounter different medium interfaces and defects. The signal processing assembly processes and analyzes the radar echo signals reflected back, extracts characteristic information, and then determines the type, position and size of the defects.

[0046] In this embodiment, due to the detachable and movable characteristics of the components in the present system, the mapping relationship research of using ground penetrating radar (GPR) to detect concealed defects under the influence of different forms of steel meshes can be realized. In the present application, the lining structure, the concealed defect and the surrounding rock are distinguished along the depth direction of the surrounding rock from the side wall of the lining structure.

[0047] The tunnel detection simulation platform can simulate various tunnel scenes and defects, has strong adaptability, solves the problems that the existing ground penetrating radar detection test platform is difficult to replace components and is inconvenient to simulate different working condition tunnel hidden defects, and provides a flexible and controllable experimental platform for researching detection methods and technologies of tunnel hidden defects. The tunnel hidden defects can be detected with high precision, the radar signal characteristics of the simulated defects are analyzed, and a hidden defect simulation detection database is constructed, thereby providing a scientific basis for interpretation of ground penetrating radar signals and defect identification in actual tunnel detection, and helping to timely discover and rectify tunnel structure hidden dangers and guarantee safe operation of the tunnel. The system components are based on clear parameter settings and adjustments, the simulated scene can be repeatedly built, and the repeatability and consistency of test results are ensured.

[0048] In a possible implementation, the surrounding rock with different dielectric constants corresponds to different particle size combinations of fine sand and gravel in the surrounding rock, different layering characteristics, and different water contents of the fine sand.

[0049] Specifically, the physical structure and electromagnetic properties of the surrounding rock are changed by selecting different particle size combinations of gravel particles, thereby affecting the dielectric constant. For example, using a coarse particle size combination of gravel particles can increase the porosity of the surrounding rock, thereby reducing the dielectric constant; conversely, using a fine particle size combination of gravel particles can reduce the porosity of the surrounding rock, thereby increasing the dielectric constant. Different layering structures in the surrounding rock can also cause changes in the dielectric constant. By simulating the layering characteristics of the surrounding rock under different geological conditions, such as horizontal layering and inclined layering, the dielectric constant of the surrounding rock can be adjusted. Different layering characteristics can affect the propagation path and reflection characteristics of electromagnetic waves in the surrounding rock, thereby changing the equivalent dielectric constant of the surrounding rock. The water content of the fine sand has a significant impact on the dielectric constant of the surrounding rock. Increasing the water content of the fine sand can increase the dielectric constant of the surrounding rock, because the dielectric constant of water is much greater than that of dry fine sand. During the simulation process, the water content of the fine sand can be controlled to adjust the dielectric constant of the surrounding rock.

[0050] In this embodiment, the surrounding rock is simulated by fine sand with a certain water content. The water content and the dielectric constant of the simulated surrounding rock can refer to the Herkelrath model. Before each measurement experiment, the structure and material properties of the surrounding rock can be adjusted in real time by changing the particle size combination of gravel, the layering characteristics, and the water content, so as to realize fine simulation of the dielectric constant difference between the surrounding rock and the hidden defects, and to establish a mapping relationship between the hidden defects and the GPR detection results under different stratum or surrounding rock conditions. The ratio of sand with different particle sizes can be used to simulate the influence of non-uniform soil and adverse geology on the ground penetrating radar detection results. Not only can different distribution forms of stratum environments be simulated, but also adverse geologies such as fracture zones, underground goaf, water inrush channels, and karst can be simulated.

[0051] In a possible implementation, the frame includes a concrete plate or a wooden plate.

[0052] The frame is made of concrete plates or wood plates with different dielectric constants according to the dielectric constant of the surrounding rock.

[0053] Specifically, according to the dielectric constant of the surrounding rock to be simulated, the frame is made of concrete plates or wood plates with appropriate dielectric constants. For example, if the surrounding rock to be simulated has a low dielectric constant, wood plates with a low dielectric constant are selected; if the surrounding rock to be simulated has a high dielectric constant, concrete plates with a high dielectric constant are selected. The difference between the dielectric constant of the surrounding rock and the dielectric constant of the frame is within a preset range, that is, the dielectric constants of the two are close.

[0054] In this embodiment, when the electromagnetic wave propagates at the interface between two different media, if the dielectric constants of the two media differ greatly, the electromagnetic wave will produce strong reflection at the interface. If the dielectric constant of the frame differs greatly from that of the surrounding rock, the electromagnetic wave emitted by the ground penetrating radar will produce obvious reflection wave when it reaches the interface between the frame and the surrounding rock. These reflected waves will interfere with the reflected waves from the target bodies such as hidden defects, making the signals received by the radar complex and chaotic, and it is difficult to accurately distinguish the effective signals from the hidden defects, thereby affecting the accurate detection and identification of the hidden defects in the tunnel. When the dielectric constants of the two are close, the reflection of the electromagnetic wave at the interface between the frame and the surrounding rock will be greatly weakened, and the signals received by the radar are mainly reflected from the target bodies such as hidden defects, reducing the interference factors, and facilitating clearer analysis and identification of the characteristic signals of the hidden defects. In addition, the frame is used to fix the fine sand, so that the fine sand does not flow during the detection process, causing the shape of the hidden defects to change.

[0055] In one possible implementation, the hidden defect simulation assembly further comprises a reinforcing member;

[0056] The reinforcing member is an insulating member arranged at the outer periphery of the frame for fixing the frame.

[0057] Specifically, the reinforcing member is made of an insulating material, and the reinforcing member can be a deformable member, wherein the deformable member is a nylon rope, a plastic band, a glass fiber, etc. These materials have good insulating properties and will not cause electromagnetic interference to the radar detection. The reinforcing member is arranged at the outer periphery of the frame, that is, the outer edge or the periphery of the frame, and the frame is fixed firmly in the detection system by means of binding, buckling, etc. According to the size and shape of the frame and the overall structure of the detection system, an appropriate fixing method is selected. For example, the corners and sides of the frame are bound with a nylon rope or a band to ensure that the frame does not displace or deform during the detection process.

[0058] In this embodiment, the reinforcing member maintains the integrity of the test device and ensures that the test device remains intact and does not collapse when the position and shape of the hidden defect are changed.

[0059] In a possible implementation, the concealed defect simulation component includes a cavity simulation component and a water film injection component, and the concealed defect includes a surrounding rock cavity and a surrounding rock cave;

[0060] The cavity simulation component of different positions, different sizes and different shapes simulates surrounding rock cavities of different positions and different shapes, and the water film injection component of different shapes simulates surrounding rock caves of different shapes; the cavity simulation component is an expanded polystyrene board.

[0061] Specifically, the cavity simulation component is an expanded polystyrene board, which has the characteristics of light weight, easy processing and good insulation performance. According to the needs of the test, the expanded polystyrene board is processed into cavity simulation components of different shapes and sizes. The processed expanded polystyrene board cavity simulation components are placed at specific positions of the surrounding rock to simulate surrounding rock cavities of different positions. The water film injection component is usually made of permeable materials, such as porous plastic pipes or specially designed water injection pipes. According to the shape of the cave to be simulated, the water film injection component is designed and manufactured. These components can be pipes or chambers of different shapes and can contain and inject fluids. The water film injection component is installed at a specific position of the surrounding rock, and then different types of fluids such as water, gas or solid-liquid mixture are injected to simulate surrounding rock caves of different shapes.

[0062] In this embodiment, the expanded polystyrene board is buried in the sand at a certain depth and position to simulate cavities of different shapes. The water film injection component is customized to process different types of fluids such as liquid, gas and solid-liquid mixture to simulate surrounding rock caves, achieve full coverage of concealed defects in wide area, full size and multiple shapes of tunnels, and improve the interpretability of ground penetrating radar detection results.

[0063] In a possible implementation, the shape of the cavity simulation component includes a sphere, an ellipsoid, a long strip and an irregular shape.

[0064] In this embodiment, the cavity simulation component of multiple shapes can simulate surrounding rock cavities of different shapes, thereby improving the diversity and flexibility of simulation to better meet the actual needs of tunnel detection.

[0065] In a possible implementation, the internal defect simulation component includes a gas injection component, a movable component and a water injection component; the internal defect includes a gas-containing cavity, a water-containing cavity and an interlayer contact not dense;

[0066] The gas injection component, the movable component and the water injection component are based on different positions of the lining pouring process in the lining structure, the gas injection component is used to simulate gas-containing cavities under different conditions;

[0067] The water injection component simulates water-containing cavities under different conditions;

[0068] The movable component simulates the interlayer contact not dense under different conditions.

[0069] In this embodiment, the lining structure can consider the influence of air-filled cavities, water-filled cavities, and interlayer contact non-compaction defects on the GPR detection results during pouring. By injecting gas into different positions of the lining structure through the gas injection component, air-filled cavity defects caused by insufficient gas discharge during construction or geological conditions are simulated. Water is injected into specific positions of the lining structure using the water injection component to simulate water-filled cavities formed by incomplete water removal during construction or groundwater infiltration. The movable component is used to simulate interlayer contact non-compaction between layers in the lining structure due to construction technology, material problems, or geological movements.

[0070] In a possible implementation, the internal defects further include lining pouring quality problems and insufficient thickness of the lining structure;

[0071] Different lining pouring defects in the lining structure simulate lining pouring quality problems under different conditions;

[0072] Different lining pouring thicknesses in the lining structure simulate insufficient thickness problems of different lining structures.

[0073] In this embodiment, the lining structure can consider the influence of air-filled cavities, water-filled cavities, and interlayer contact non-compaction defects on the GPR detection results during pouring. By injecting gas into different positions of the lining structure through the gas injection component, air-filled cavity defects caused by insufficient gas discharge during construction or geological conditions are simulated. Water is injected into specific positions of the lining structure using the water injection component to simulate water-filled cavities formed by incomplete water removal during construction or groundwater infiltration. The movable component is used to simulate interlayer contact non-compaction between layers in the lining structure due to construction technology, material problems, or geological movements.

[0074] In a possible implementation, the internal defect simulation component further includes a steel bar corrosion simulation component for simulating steel bar corrosion;

[0075] The steel bar corrosion simulation component simulates steel bar corrosion under different conditions by using corrosion media with different injection amounts and different reaction times.

[0076] In this embodiment, different degrees of steel bar corrosion are simulated by controlling the injection amount and reaction time of the corrosion medium, thereby more comprehensively reflecting the types of internal defects that may occur in the tunnel lining structure.

[0077] In a possible implementation, the types of lining structures include lining structures of drill-and-blast tunnels and lining structures of shield tunnels;

[0078] The lining structure of the drill-and-blast tunnel comprises an arch, primary support, waterproof board, secondary lining and reinforcing component, the arch is connected with the primary support, the primary support is connected with the waterproof board, the waterproof board is connected with the secondary lining, and the secondary lining is connected with the reinforcing component.

[0079] In the embodiment, the lining structure is a local cut block of an actual tunnel, and the detailed size can be referred to a tunnel design drawing.

[0080] The radar assembly comprises a radar antenna, a main machine, sampling control software, connecting lines and a ranging wheel, etc.

[0081] The lining structure is a local cut block of an actual tunnel, and the detailed size can be referred to a tunnel design drawing.

[0082] The lining structure is a local cut block of an actual tunnel, and the detailed size can be referred to a tunnel design drawing.

[0083] Before detection, the size of the prefabricated component and the electromagnetic property of the surrounding rock are determined according to the actual tunnel parameters, and the frequency of the radar antenna is selected according to reliable theoretical calculation and engineering application experience, generally in the range of 1MHz-1GHz, the water content and particle size ratio of the sand used for simulating the surrounding rock are calculated, and the effective detection and clear imaging of the hidden defects behind the lining wall are realized.

[0084] The present application has simple operation process. First, key components such as prefabricated lining, hidden defects and poor geology are needed, and radar measuring lines are demarcated according to the test site environment and the size of each component. Then, the frame and reinforcing members are selected, and the materials such as sand are matched according to the on-site geological exploration data. Finally, while the test platform is being built, the antenna frequency of the ground penetrating radar detection system is determined according to the medium constant properties, effective detection depth, expected test accuracy, etc., and the sampling is debugged.

[0085] The test method refers to the test design, sub-module production, test platform construction, pre-test and verification, control test, data preprocessing and rule analysis process, as shown in Figure 2 Using this test method, the mapping relationship between different structure forms and material properties of the research objects such as lining structure, surrounding rock and hidden defects and GPR detection results can be obtained. After the model test platform is built, the control conditions that need to be set are selected according to the test purpose, such as the size of the reinforcing mesh, the thickness of the lining, the interlayer contact state and shape, the properties and block shape of the surrounding rock, the stratification characteristics of the rock / soil layer, and the type, size, filling material and filling ratio of the hidden defects. According to the control variable method, while keeping other factors consistent, the setting of a certain sub-module of the test platform is changed, and the control test is carried out. According to the collected test results, the mapping relationship between different research objects and GPR detection results is summarized from the angles of B-Scan images and A-Scan signals, which provides theoretical support for tunnel site hidden defect detection and data interpretation.

[0086] The B-Scan image rule refers to the rule that the wave group shape characteristics of hidden defects in the B-Scan images collected under different test conditions change with the change of test conditions. The same data preprocessing operations such as correction of zero offset, adjustment of gain, digital filtering, background elimination, anomaly labeling and positioning are carried out on the B-Scan images collected in each test group, and the wave group shape of the hidden defect target in the image is obtained. According to the change of the wave group shape, the mapping relationship between the B-Scan image and the test condition is formed. The present application sets different mesh sizes of reinforcing mesh in the secondary lining structure, such as no reinforcing mesh, 0.1x0.1, 0.15x0.15, 0.2x0.2, 0.25x0.25, 0.3x0.3, 0.35x0.35 and 0.4x0.4 reinforcing mesh, as an example, and establishes the mapping relationship between GPR detection results and surrounding rock internal cavities, and the B-Scan image change rule is as shown in Figure 3 .

[0087] The A-Scan signal rule refers to the rule that the amplitude and spectral characteristics of the A-Scan signal collected at the hidden defect position change with the test conditions. After the same data preprocessing operation is carried out on the B-Scan image collected in each test, the path and depth position of the hidden defect in the B-Scan image are located, the frequency spectrum of the path data is obtained by using the fast Fourier transform (FFT) according to the two-way time difference method, and the electric / magnetic field intensity amplitude of the depth position is extracted. The mapping relationship of the frequency spectrum and the field strength amplitude with the test conditions is arranged, and the linear / nonlinear fitting method is used to obtain the change rule of the A-Scan signal. The present application sets different grid sizes of the steel mesh in the two-liner structure, such as: no steel mesh, 0.1*0.1, 0.15*0.15, 0.2*0.2, 0.25*0.25, 0.3*0.3, 0.35*0.35, and 0.4*0.4 steel mesh as examples, and establishes the mapping relationship between the GPR detection result and the cavity in the surrounding rock, and the A-Scan signal change rule is as shown in Figure 4

[0088] The above examples are only used to illustrate the technical solutions of the present application, but not to limit them; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.​

Claims

1. A tunnel hidden defect simulation and detection system, installed on the ground free from electromagnetic interference, characterized in that, include: Lining structure, concealed defect simulation components, radar components, and signal processing components; The lining structure includes steel meshes of different grid sizes and internal defect simulation components; Reinforcing meshes of different sizes are used to simulate reinforcing meshes under different conditions, and the internal defect simulation component is used to simulate lining structures under different internal defects; The concealed defect simulation component is located on one side of the lining structure. The concealed defect simulation component includes a frame, a concealed defect simulation component, and surrounding rock. A cavity is formed between the frame and the lining structure. Surrounding rock with different dielectric constants is set in the cavity to simulate geological characteristics under different conditions. The concealed defect simulation component is located in the surrounding rock and is used to simulate concealed defects. The radar component is used to transmit and receive electromagnetic waves within a preset frequency range. The signal processing component is used to process the radar echo signals received by the radar, determine the radar signal characteristics under different lining structure internal defects and tunnel hidden defects conditions based on the radar echo signals, and construct a hidden defect simulation detection database.

2. The tunnel hidden defect simulation and detection system according to claim 1, characterized in that, The particle size distribution, stratification characteristics, and water content of fine sand in surrounding rocks with different dielectric constants are different.

3. The tunnel hidden defect simulation and detection system according to claim 1, characterized in that, The frame includes a concrete slab or a wooden board; For surrounding rocks with different dielectric constants, the frame is made of concrete slabs or wooden boards with different dielectric constants.

4. The tunnel hidden defect simulation and detection system according to claim 1, characterized in that, The hidden defect simulation component also includes reinforcement components; The reinforcing component is an insulating element, located on the outer periphery of the frame, and is used to fix the frame.

5. The tunnel hidden defect simulation and detection system according to claim 1, characterized in that, The hidden defect simulation component includes a cavity simulation component and a water film injection component, and the hidden defects include surrounding rock cavities and surrounding rock karst caves; Void simulation components of different locations, sizes and shapes simulate cavities in surrounding rock of different locations and forms, and water film injection components of different forms simulate karst caves in surrounding rock of different forms; wherein, the void simulation component is an expanded polystyrene board.

6. The tunnel hidden defect simulation and detection system according to claim 5, characterized in that, The shapes of the cavity simulation components include spherical, ellipsoidal, elongated, and irregular shapes.

7. The tunnel hidden defect simulation and detection system according to claim 1, characterized in that, The internal defect simulation component includes an air-injection component, a movable component, and a water-injection component; the internal defects include air-containing voids, water-containing voids, and poor interlayer contact. The air injection component, movable component, and water injection component are located at different positions in the lining structure based on the lining casting process. The air injection component is used to simulate air-containing cavities under different conditions. The water injection component simulates water-bearing cavities under different conditions; The movable component simulates the non-compact interlayer contact under different conditions.

8. The tunnel hidden defect simulation and detection system according to claim 7, characterized in that, The internal defects also include: problems with the quality of the lining pouring and insufficient thickness of the lining structure; The different lining pouring defects in the lining structure simulate lining pouring quality problems under different conditions; The different lining pouring thicknesses in the lining structure simulate the problem of insufficient thickness in different lining structures.

9. The tunnel hidden defect simulation and detection system according to claim 1, characterized in that, The internal defect simulation component also includes a steel corrosion simulation component for simulating steel corrosion. The steel reinforcement corrosion simulation component simulates steel reinforcement corrosion under different conditions by using corrosive media with different injection volumes and reaction times.

10. The tunnel hidden defect simulation and detection system according to claim 1, characterized in that, The types of lining structures include the lining structures of drill-and-blast tunnels and the lining structures of shield tunnels. The lining structure of the drill-and-blast tunnel includes an arch frame, initial support, waterproof membrane, secondary lining, and reinforcing components. The arch frame is connected to the initial support, the initial support is connected to the waterproof membrane, the waterproof membrane is connected to the secondary lining, and the secondary lining is connected to the reinforcing components. The lining structure of the shield tunnel includes segments, bolts, and a grouting layer. The segments are connected to the bolts and the grouting layer.

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