Multi-field coupling test device and method for simulating deterioration of seabed shield tunnel structure

Abstract

The invention provides a multi-field coupling test device and method for simulating deterioration of a seabed shield tunnel structure, and the device comprises a segmental lining member which is annularly arranged, and the segmental lining member is formed by pouring concrete and reinforcing steel bars arranged in the concrete; the hoop force applying module comprises a force applying assembly arranged on the periphery of the segmental lining component; a filling module; a data acquisition module; wherein in the test process, erosion liquid is injected into the sealed cavity through the injection hole, and a direct-current electric field is applied between the anode piece and the cathode piece to drive erosion ions to directionally migrate in the concrete, so that the corrosion of steel bars and the degradation of the concrete are accelerated; and the data acquisition module is used for monitoring the moisture permeation state and the stress state in the segmental lining component and the water pressure value in the sealed cavity in real time.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of tunnel engineering test, in particular to a multi-field coupling test device and method for simulating the structural degradation of a submarine shield tunnel. BACKGROUND

[0002] Shield tunnel is the core structure form of modern urban subway, highway, railway, water conservancy and municipal pipeline underground engineering. The long-term safety and durability of the permanent structure, i.e. the assembled segment lining, directly relate to the operation safety of the entire underground network. The traditional tunnel design theory mainly focuses on the mechanical response of the segment under external water and soil load, and does not consider the structural performance degradation during the service process of the tunnel and the resulting long-term safety problem of the structure. However, with the development of underground space to greater depth, more complex geological conditions and more extreme service environment, shield tunnel structure is facing severe challenges, mainly in the following aspects.

[0003] Extreme erosion environment leads to structural degradation of the lining: the tunnel in the erosion environment represented by the submarine shield tunnel is subjected to the combined action of high water and soil load, high permeable water pressure and high concentration of erosion ions during its service process. The assembled segment lining inevitably appears phenomena such as steel bar corrosion, concrete cracking and spalling. Especially, the superimposed effect of the physical-chemical field and the mechanical field of structural degradation in the erosion environment makes the main structure of the tunnel (segment lining) present a spiral accelerating degradation process, which greatly shortens the service life of the structure.

[0004] Chain hazards of joint leakage: the segment joint is the first line of defense for waterproofing of the shield tunnel, but also the weakest link. Under the action of bending load, structural deformation and long-term load, the joint sealing material may fail, leading to leakage. The leakage water carries erosion ions (such as chloride ions and sulfate ions) into the interior of the concrete, inducing corrosion of the bolts and joint steel bars, degradation of the concrete near the joint, and reduction of the joint stiffness and strength, which will increase the structural deformation and weaken the sectional safety redundancy, seriously affecting the safety and applicability of the tunnel structure in long-term service. SUMMARY

[0005] The present application provides a multi-field coupling test device for simulating the structural degradation of a submarine shield tunnel, which realizes the simulation and evaluation of the structural degradation behavior of the submarine shield tunnel under the multi-field coupling action of micro-electric field, high-pressure seepage and continuous load. In addition, the present application also provides a test method suitable for the above-mentioned multi-field coupling test device for simulating the structural degradation of a submarine shield tunnel.

[0006] In order to achieve the above-mentioned purpose, the present application provides the following technical solutions: A multi-field coupling test device for simulating the structural degradation of a submarine shield tunnel, comprising: A segmental lining component is arranged in a ring shape and is formed by pouring concrete and reinforcing steel into the concrete. A hoop force applying module includes a force applying assembly arranged on the outer periphery of the segmental lining component. A filling module includes a first sealing cover sealing the first end of the segmental lining component, a second sealing cover sealing the second end of the segmental lining component, a connecting rod assembly connecting the first sealing cover and the second sealing cover, and a water injection pump, the first sealing cover is located on top of the second sealing cover, and the first sealing cover is provided with an injection hole, a water stop is arranged between the first sealing cover and the segmental lining component and between the second sealing cover and the segmental lining component, and the first sealing cover, the second sealing cover and the segmental lining component form a sealed cavity. A data acquisition module includes an electrode array embedded in the concrete, a resistivity acquisition instrument electrically connected to the electrode array, a water pressure sensor, and a component internal force sensor and a data acquisition instrument used in conjunction with the component internal force sensor. During the test, the erosion liquid is injected into the sealed cavity through the injection hole, and the erosion liquid is pressurized based on a preset penetration water pressure, the pressurized erosion liquid drives the erosion ions inside to migrate to the inside of the concrete, thereby inducing steel corrosion and concrete deterioration, and the data acquisition module is used to monitor the water penetration state, stress state inside the segmental lining component and water pressure value in the sealed cavity in real time.

[0007] Optionally, the multi-field coupling test device for simulating the deterioration of the subsea shield tunnel structure further includes an electrochemical corrosion module, the electrochemical corrosion module includes a cathode arranged coaxially with the segmental lining component and a power supply for conducting an anode and the cathode, the steel forms the anode, and a direct current electric field is applied between the anode and the cathode to drive the erosion ions in the erosion liquid to migrate directionally in the concrete, thereby accelerating the steel corrosion and concrete deterioration.

[0008] Optionally, the multi-field coupling test device for simulating the deterioration of the subsea shield tunnel structure, the connecting rod assembly is composed of a plurality of stretchable pull rods.

[0009] Optionally, the multi-field coupling test device for simulating the deterioration of the subsea shield tunnel structure, the force applying assembly includes a metal wire wound around the outer peripheral wall of the segmental lining component and a tensioning device for tensioning the metal wire.

[0010] Optionally, in the multi-field coupling test device for simulating the deterioration of a shield tunnel structure under the seabed, the segment lining member is composed of a plurality of annular segments combined along the axial direction of the segment lining member; or, the segment lining member is composed of a plurality of arc-shaped segments; or, the segment lining member is composed of a single annular segment.

[0011] Optionally, in the multi-field coupling test device for simulating the deterioration of a shield tunnel structure under the seabed, the electrode array is embedded in the concrete and arranged in an array along the circumferential direction of the segment lining member.

[0012] Optionally, in the multi-field coupling test device for simulating the deterioration of a shield tunnel structure under the seabed, the data acquisition module further comprises a distributed optical fiber sensor arranged on the outer peripheral wall and the inner peripheral wall of the segment lining member along the circumferential direction of the segment lining member.

[0013] Optionally, in the multi-field coupling test device for simulating the deterioration of a shield tunnel structure under the seabed, the first sealing cover is provided with a through hole, the second sealing cover is provided with a groove on the side facing the sealed cavity, and the cathode member penetrates through the through hole and is embedded in the groove, wherein the axis of the through hole and the groove coincides with the axis of the segment lining member.

[0014] Optionally, in the multi-field coupling test device for simulating the deterioration of a shield tunnel structure under the seabed, the first sealing cover and the second sealing cover are both made of metal, the side of the first sealing cover and the second sealing cover facing the sealed cavity is provided with an insulating layer, and an insulating sealing member is arranged between the through hole and the cathode member.

[0015] A multi-field coupling test method for simulating the deterioration of a shield tunnel structure under the seabed, which is applicable to the multi-field coupling test device for simulating the deterioration of a shield tunnel structure under the seabed and comprises the following steps: Step 1: Start the tensioning device, use the tensioning device to apply circumferential constraint to the segment lining member through the metal strand, and gradually increase the tensioning force in a preset number of steps until the uniform pressure on the outer peripheral wall of the segment lining member reaches a first preset value; Step 2: Start the water injection pump, inject the erosion liquid into the sealed cavity, and gradually pressurize the erosion liquid in the sealed cavity until the uniform water pressure on the inner peripheral wall of the segment lining member reaches a second preset value; Step 3: Connect the positive electrode of the power supply to the anode member, and connect the negative electrode of the power supply to the cathode member; Step 4: Start the data acquisition module.

[0016] This application provides a multi-field coupled test device for simulating the structural deterioration of a submarine shield tunnel. It applies circumferential constraint force to the lining components using a hoop force application module, and injects corrosive liquid containing corrosive ions into a sealed cavity via an injection module. The injection pump is pressurized based on a preset seepage water pressure, causing the corrosive ions within the pressurized liquid to migrate into the concrete, thereby inducing steel corrosion and concrete deterioration. A data acquisition module monitors in real time the water seepage state, stress state, and water pressure within the sealed cavity of the lining components. This allows for the simulation and evaluation of the structural deterioration behavior of a submarine shield tunnel under the multi-field coupled action of micro-electric field – high-pressure seepage – continuous loading.

[0017] In this way, this application overcomes the problem of traditional tests that only consider the influence of a single factor, and realistically simulates the complex working conditions of high water pressure, low oxygen seawater infiltration, chloride ion corrosion, electrochemical corrosion of steel bars and continuous loading in the actual service environment of submarine tunnels; the electroosmotic pressure module accelerates the corrosion process of steel bars, significantly shortens the test cycle and improves simulation efficiency; through the setting of the data module, various state parameters of the tunnel lining components can be monitored in real time, thus reflecting the deterioration behavior of the tunnel lining components under multi-field coupling. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0019] Figure 1 This is a structural schematic diagram of the segment lining component provided in this application; Figure 2 A structural schematic diagram of a segment lining component consisting of a single annular segment provided in this application; Figure 3 A structural schematic diagram of a segment lining component composed of multiple annular segments provided in this application; Figure 4 A structural schematic diagram of a segment lining component composed of multiple arc-shaped segments provided in this application; Figure 5 A schematic diagram of the internal structure of the segment lining component provided in this application; Figure 6 Assembly process diagram of the segment lining components provided in this application; Figure 7 A schematic diagram of the arrangement of the water pressure sensors provided in this application; Figure 8 schematic diagram of an electrode arrangement provided for the present application; Figure 9 schematic diagram of a fiber optic sensor arrangement provided for the present application; Figure 10 schematic diagram of a segment lining member outer peripheral wall under radial pressure provided for the present application; Figure 11 schematic diagram of a segment lining member inner peripheral wall under radial pressure provided for the present application; Figure 12 schematic diagram of a segment lining member under radial pressure provided for the present application.

[0020] 1, segment lining member; 2, reinforcing bar; 3, first sealing cover; 4, second sealing cover; 5, connecting rod assembly; 6, water injection hole; 7, cathode; 8, electrode array; 9, water pressure sensor; 10, distributed fiber optic sensor; 11, metal strand; 12, tensioning device; 13, anchor bolt. DETAILED DESCRIPTION

[0021] The present application provides a multi-field coupling test device for simulating the structural degradation of a submarine shield tunnel, which realizes the simulation and evaluation of the structural degradation behavior of a submarine shield tunnel under the multi-field coupling action of a micro electric field, high pressure seepage and sustained load. In addition, the present application also provides a test method suitable for the above-mentioned multi-field coupling test device for simulating the structural degradation of a submarine shield tunnel.

[0022] As Figures 1-12As shown, the application provides a multi-field coupling test device for simulating the deterioration of a seabed shield tunnel structure, comprising: a segment lining component 1 arranged in a ring shape, the segment lining component 1 being cast from concrete and steel bars 2; a hoop force applying module comprising a force applying assembly arranged on the outer periphery of the segment lining component 1; a filling module comprising a first sealing cover 3 sealing the first end of the segment lining component 1, a second sealing cover 4 sealing the second end of the segment lining component 1, a connecting link assembly 5 connecting the first sealing cover 3 and the second sealing cover 4, and a water filling pump, the first sealing cover 3 being located on top of the second sealing cover 4, and the first sealing cover 3 being provided with an injection hole, water stopping elements being arranged between the first sealing cover 3 and the segment lining component 1 and between the second sealing cover 4 and the segment lining component 1, and the first sealing cover 3, the second sealing cover 4 and the segment lining component 1 forming a sealed cavity; a data acquisition module comprising an electrode array 8 embedded in the concrete, a resistivity acquisition instrument electrically connected to the electrode array 8, a water pressure sensor 9, and a component internal force sensor and a data acquisition instrument used in conjunction with the component internal force sensor; wherein, during the test, the sealed cavity is filled with an erosion liquid through the injection hole, and the filling pump is pressurized based on a preset osmotic water pressure, the pressurized erosion liquid drives the erosion ions inside it to migrate to the inside of the concrete, thereby inducing corrosion of the steel bars 2 and deterioration of the concrete, and the data acquisition module is used to monitor the water permeation state, stress state and water pressure value in the sealed cavity inside the segment lining component 1 in real time.

[0023] It should be noted that the water stopping element is a water stopping adhesive tape; the water filling pump is preferably a high pressure water filling pump; the erosion liquid is sea water in the environment of the segment lining component 1 or sea water prepared by chemical experiments, and the erosion liquid is a liquid containing specific erosion ions, including Cl - , SO4 2- , Mg 2+ ; the water pressure sensor 9 is used to monitor the water pressure value of the erosion liquid in the sealed cavity; the electrode array 8 and the resistivity acquisition instrument electrically connected to the electrode array 8 are used to reflect the water permeation state inside the segment lining component 1.

[0024] It should also be noted that the component internal force sensor is a distributed optical fiber sensor 10, which is arranged along the axial direction of the steel bars 2 and along the circumferential direction on the inner and outer peripheral wall surfaces of the segment lining component 1, and preferably, the distributed optical fiber sensor 10 is arranged equidistantly along the circumferential direction on the inner and outer peripheral wall surfaces of the segment lining component 1, and the data acquisition instrument is an optical fiber demodulator, the component internal force sensor is used to sense the strain or internal force state of the segment lining component 1 under complex loads and environmental actions, and the matched data acquisition instrument is responsible for collecting, converting and transmitting the signals, and the two work together to realize real-time monitoring and quantitative evaluation of the mechanical properties of the structure.

[0025] Specifically, the segmental lining component 1 is poured by concrete and steel bars 2, and is the test object of the application, and the size of the segmental lining component 1 and the size of the object to be simulated are in a specified geometric scale ratio, at the same time, the segments forming the segmental lining component 1 and the joint structure between the segments are designed according to the actual engineering segment scale, for simulating the assembled segmental lining ring of the shield tunnel in the actual engineering. Based on the thin-walled cylinder theory, by applying external radial pressure and internal radial water pressure, the two are respectively converted into hoop compressive stress (the specific formula will be explained later) and tensile stress (the specific formula will be explained later) on the cross section of the segmental lining component 1 according to the principle of elasticity, and the two are superimposed on each other, so as to accurately control the complex stress state of the model cross section, and make it reach the preset stress state of the test.

[0026] It should be noted that the water pressure in the sealed cavity not only generates hoop tension in the segmental lining component 1, but also acts as a permeation water pressure, and truly simulates the leakage development process of key parts such as segmental lining and joints under high water pressure environment, and the stress state and the permeation water pressure environment are kept uniform and consistent in each ring scale segmental lining unit.

[0027] More specifically, the force applying assembly is arranged on the outer peripheral wall of the segmental lining component 1 and is used for applying radial restraint force to the outer peripheral wall of the segmental lining component 1. The radial hydrostatic pressure is applied to the segmental lining component 1 by injecting the erosion liquid into the sealed cavity through the water injection pump, so as to apply the hoop tension and the bearing permeation water pressure in the segmental lining test piece, and the difference between the hoop tension and the hoop compression is adjusted, so as to realize the permeation of water in the segmental lining under the specified stress state and the permeation water pressure.

[0028] It should be noted that the force applying assembly can apply the radial restraint force to the segmental lining component 1 in stages, and the pressure of the erosion liquid injected into the sealed cavity by the water injection pump can also be gradually increased.

[0029] In this way, the application overcomes the problem of only considering a single factor in the traditional test process, and truly simulates the complex working conditions of high water pressure, low oxygen seawater permeation, chloride ion erosion, steel bar 2 electrochemical corrosion and sustained load in the actual service environment of the submarine tunnel; the electrochemical permeation pressure module accelerates the corrosion progress of the steel bar 2, significantly shortens the test period, and improves the simulation efficiency; through the setting of the data module, the state parameters of the segmental lining component 1 can be monitored in real time, so as to more comprehensively reflect the deterioration behavior of the segmental lining component 1 under the multi-field coupling action.

[0030] Further, the device further comprises an electrochemical corrosion module, including a cathode 7 coaxially arranged with the segment lining member 1 and a power supply for conducting the anode and the cathode 7, and the reinforcing steel 2 constitutes the anode, wherein a direct current electric field is applied between the anode and the cathode 7 to drive the corrosion ions in the corrosion liquid to migrate in the concrete in a directional manner, thereby accelerating the corrosion of the reinforcing steel and the deterioration of the concrete.

[0031] The positive electrode of the direct current stabilized power supply is connected with the reinforcing steel 2, and the negative electrode is connected with the copper rod, thereby establishing a stable electric potential field between the sealed cavity and the corrosion liquid. Specifically, the negatively charged chloride ions (Cl - ) in the corrosion liquid migrate to the anode (reinforcing steel 2) in a directional manner under the action of the electric field force. The electrochemical reaction of iron occurs on the surface of the anode (reinforcing steel 2): Fe → Fe 2+ + 2e - , and the chloride ions migrating to the surface of the reinforcing steel 2 will destroy the stability of the passivation film and form a corrosion cell; and the hydrogen evolution oxygen reduction reaction occurs on the surface of the cathode 7 (copper rod). The entire system constitutes a complete electrolytic circuit. By adjusting the output voltage or current of the direct current stabilized power supply, the electric field strength is controlled to drive the anions (such as chloride ions) in the corrosion liquid to migrate to the anode in a directional manner, thereby achieving the following two functions: one is to accelerate the penetration speed of the corrosive medium in the concrete, and the other is to promote the electrochemical corrosion reaction on the surface of the reinforcing steel 2. The electrochemical corrosion module works synchronously with the ring force applying module and the filling module to form a test environment of micro-electric field-high pressure seepage-continuous load multi-field coupling, thereby providing an efficient test means for studying the long-term durability evolution of the shield segment under high water pressure environment. The data acquisition module is used to monitor the water penetration state and stress state inside the segment lining member 1 and the water pressure value in the sealed cavity in real time, thereby realizing the simulation and evaluation of the structural deterioration behavior of the submarine shield tunnel under the action of micro-electric field-high pressure seepage-continuous load multi-field coupling.

[0032] It should be noted that the cathode 7 is a copper rod, and the power supply is a direct current stabilized power supply.

[0033] The connecting rod assembly 5 is composed of a plurality of pull rods with telescopic function. During the simulation experiment, the height of the segment lining member 1 is based on the simulation object, and in the simulation process, there is a case of disassembling a specific segment. It should be noted that when the segment lining member 1 is composed of a plurality of segments, it can be disassembled based on the test requirements, which will cause the height of the segment lining member 1 to be different. The pull rod has a telescopic function, which can dynamically adjust the length according to the change of the number of assembled layers of the segment lining member 1 in the test process, thereby improving the practicability of the pull rod.

[0034] It should be noted that the outer peripheral wall of the pull rod is provided with threads, and the first sealing cover 3 and the second sealing cover 4 are firmly pressed against the two ends of the segment lining member 1 by screwing the threads with the anchor bolts 13.

[0035] In an optional embodiment, the force applying assembly comprises metal strands 11 arranged around the outer peripheral wall of the segmental lining member 1 and tensioning devices 12 for tensioning the metal strands 11. The metal strands 11 can be, but are not limited to, steel strands, and the metal strands 11 are provided in multiple, the tensioning devices 12 can be, but are not limited to, hydraulic jacks or servo electric tensioners, and the two ends of the metal strands 11 are connected with the tensioning devices 12. By synchronously tensioning all the metal strands 11 through the tensioning devices 12, a uniform radial restraint force is applied to the segmental lining member 1, which, according to the thick-walled cylinder theory in the elastic mechanics, can be directly equivalent to a uniform hoop stress on the segmental cross section, facilitating accurate setting of the initial stress level and improving the test repeatability and scientificity. At the same time, the steel strand bundle is used to simulate the external pressure, replacing the complex multi-jack loading system, greatly reducing the cost and complexity of the device.

[0036] In this way, the synchronous tensioning of the multiple metal strands 11 ensures the continuous and symmetrical distribution of the radial pressure along the circumferential direction of the segment, avoiding local stress concentration and truly reproducing the mechanical characteristics of the formation confining pressure; the combination of the metal strands 11 and the tensioning devices 12 is flexible, suitable for segment models of different sizes and different reinforcement forms, and the tensioning devices 12 can be adjusted in real time to support the staged loading and long-term load holding test.

[0037] In an optional embodiment, the segmental lining member 1 is composed of multiple annular segments arranged along the axial direction of the segmental lining member 1; or, the segmental lining member 1 is composed of multiple arc-shaped segments; or, the segmental lining member 1 is composed of a single annular segment. It can be understood that when multiple annular segments are longitudinally connected in series, the influence of the longitudinal segment joint on the seepage path can be investigated; when further using arc-shaped segments and implementing staggered joint assembly, the more complex three-dimensional seepage behavior under the staggered joint assembly condition in actual engineering can be simulated. This design greatly expands the research dimension and simulation capability of the test device.

[0038] In other optional embodiments, the segmental lining member 1 can also use a single annular module, which is suitable for one-dimensional radial seepage analysis of the segment ring under simplified conditions.

[0039] Among them, the electrode array 8 is embedded in the concrete and is distributed equidistantly along the circumferential direction of the segmental lining member 1.

[0040] When the electrode array 8 is distributed along the circumferential direction, the corrosion state of the steel bars caused by joint leakage and local cracks can be identified.

[0041] The electrode array 8 can also be distributed in a grid shape along the circumferential direction, and the electrode array 8 is guided and led out to a data acquisition instrument for inverting the water penetration depth and distribution through the resistivity change.

[0042] In other optional embodiments, the electrode array 8 is embedded in the concrete and arranged in an array along the circumference of the segment lining member 1.

[0043] In optional embodiments, the data acquisition module further comprises a distributed optical fiber sensor 10 arranged along the circumference of the segment lining member 1 on the outer peripheral wall and the inner peripheral wall of the segment lining member 1, so as to monitor the structural stress state and local strain changes.

[0044] In optional embodiments, the first sealing cover 3 is provided with a through hole, and the second sealing cover 4 is provided with a groove on the side facing the sealing cavity, and the cathode 7 passes through the through hole and is embedded in the groove, wherein the axis of the through hole and the groove coincides with the axis of the segment lining member 1. Specifically, a smooth copper rod is vertically inserted into the groove from top to bottom, and during the insertion process, a special positioning clamp is used to ensure that the axis of the copper rod always coincides with the central axis of the segment lining member 1. In this way, firstly, the symmetry and uniform distribution of the electric field are improved; secondly, the stability of the cathode 7 in the sealing cavity is improved.

[0045] In optional embodiments, the first sealing cover 3 and the second sealing cover 4 are both made of metal, the side of the first sealing cover 3 and the second sealing cover 4 facing the sealing cavity is provided with an insulating layer, and an insulating sealing element is arranged between the through hole and the cathode 7. The insulating sealing element is preferably a high-pressure waterproof insulating sealing element. Specifically, the upper end of the copper rod (referring to the end protruding from the first sealing cover 3 and away from the sealing cavity) is processed with external threads, and after passing through the first sealing cover 3, it is screwed with the internal threaded hole of the high-pressure waterproof insulating sealing element. The insulating sealing element adopts a multi-layer structure design, from bottom to top, it includes a fluororubber sealing ring, a polytetrafluoroethylene insulating bushing and a stainless steel compression flange. By symmetrically tightening the bolts on the compression flange, the sealing ring is uniformly deformed in the radial direction, achieving reliable sealing in a high-pressure water environment.

[0046] The insulating layer is an insulating layer sprayed on the inner surface (the side facing the sealing cavity) of the first sealing cover 3 and the second sealing cover 4.

[0047] In this way, electrical insulation and pressure sealing in a high-pressure water environment are achieved.

[0048] It should be noted that the first sealing cover 3 and the second sealing cover 4 are both made of high-strength steel plates.

[0049] A multi-field coupling test method for simulating the deterioration of a shield tunnel structure under the sea, which is applicable to the multi-field coupling test device for simulating the deterioration of a shield tunnel structure under the sea and comprises: Step 1: Start the tensioning device 12, use the tensioning device 12 to apply a circumferential constraint to the segment lining member 1 through the metal strand 11, and gradually increase the tensioning force in a preset number of steps until the uniform pressure (i.e., the hoop force) on the outer peripheral wall of the segment lining member 1 reaches a first preset value.

[0050] The surface of the steel bar 2 at the predetermined monitoring points is treated by surface grinding, acetone cleaning, etc. The fiber Bragg grating sensor is tightly adhered to the surface of the steel bar 2 along the axial direction of the steel bar 2 using high-temperature epoxy glue. All fiber leads are fixed along the direction of the steel bar 2 and are concentrated out of the concrete protective layer and connected to the fiber demodulator. In this way, the fiber Bragg grating sensor converts the local strain of the steel bar 2 into a change in the wavelength of light, and the fiber demodulator reads and analyzes the wavelength change of the FBG and outputs accurate strain data. After the steel bar 2 concrete ring / arc module is prepared, thanks to the modular assembly design of the device, various test conditions can be flexibly configured according to the specific research objectives, such as a single ring segment or multiple ring segments and multiple arc segments spliced together. When assembling the segment lining member 1, a joint waterproof pad is installed at the joint according to the test requirements, and then the ring segment lining member 1 is obtained. To monitor internal penetration, an electrode array 8 is embedded in the segment lining member 1 at key sections (such as the joint affected area). The electrodes are distributed in a grid pattern, and the wires are led out to the data acquisition instrument. The surface of the segment lining member 1 is ground to ensure that its contact surface with the steel strand is flat. A number of distributed fiber optic sensors 10 are evenly arranged on the inner and outer walls of the segment lining member 1 in the axial direction to collect stress and deformation data. At the same time, a water pressure sensor 9 is arranged at the bottom of the sealed cavity to accurately monitor the internal water pressure.

[0051] The segment lining member 1 is placed on the second sealing cover 4, and a water stop rubber strip is arranged between the joint surfaces of the two. During installation, the center of the second sealing cover 4 and the segment lining member 1 should be strictly centered to ensure accurate alignment of the sealing surface. Then the first sealing cover 3 is placed on the segment lining member 1, and a water stop rubber strip is also arranged between the joint surfaces of the two. During installation, the center of the first sealing cover 3 and the segment lining member 1 should be strictly centered to ensure accurate alignment of the sealing surface. Finally, six high-strength stretchable pull rods are used to symmetrically arrange the first sealing cover 3 and the second sealing cover 4. The six pull rods are gradually screwed onto the first sealing cover 3 and the second sealing cover 4 to ensure the sealing reliability of the entire sealed cavity. A through hole, i.e. a copper rod insertion port, is accurately processed at the center of the first sealing cover 3. A smooth copper rod is vertically inserted from the top to the bottom, and a special positioning clamp is used to ensure that the axis of the copper rod always coincides with the center axis of the segment lining member 1 during insertion. The upper end of the copper rod is threaded, and after passing through the sealing cover, it is screwed with the internal threaded hole of the insulating sealing element.

[0052] When the test starts, first start the tensioning device 12 to symmetrically and stepwise tension the circumferentially uniformly arranged steel strands. The tensioning process uses force control mode and gradually increases. Each level of load lasts for 3-5 minutes, and the next level of load is applied after the data is stable until the preset external radial pressure value (i.e. the first preset value) is reached. This stage makes the segment lining member 1 form a tight hoop state in the radial direction and establishes a stable initial ring stress field in its cross section.

[0053] Step 2, start the water injection pump, inject the erosion liquid into the sealed cavity, and gradually pressurize the erosion liquid inside the sealed cavity until the uniform pressure (i.e. the expansion force) on the inner circumferential wall of the segment lining member 1 reaches a second preset value, and the reading of the water pressure sensor is the second preset value.

[0054] When the segment lining member 1 is in a pre-formed fastening state in the radial direction, the water injection pump is started to inject the erosion liquid into the sealed cavity through the two water injection holes 6 formed in the first sealing cover 3 and gradually pressurize, and finally reach the predetermined stress state. Through the distributed optical fiber sensor 10 distributed on the inner and outer surfaces of the segment lining member 1, the strain and deformation data of the segment lining member 1 under the load are collected in real time, and the actual stress distribution state of the segment lining member 1 is dynamically obtained based on the analysis and inversion of the monitoring data by the elastic mechanics theory. As shown in Figure 10 , specifically, the hoop stress (positive section vertical principal stress) inside the segment lining member 1 under the action of the external pressure is: ; ; ; Wherein: a is the inner radius; b is the outer radius; t is the wall thickness; is the hoop stress (positive section vertical principal stress) inside the segment lining member 1 under the action of the external pressure; P o is the external radial pressure; F is the total tension of the steel strand; L is the axial length of the circular ring specimen; D is the average circumference of the circular ring specimen.

[0055] As shown in Figure 11 , specifically, the hoop stress (positive section vertical principal stress) inside the segment lining member 1 under the action of the internal pressure is: ; Wherein: a is the inner radius; b is the outer radius; t is the wall thickness; p i is the internal radial pressure; is the hoop stress (positive section vertical principal stress) inside the segment lining member 1 under the action of the internal pressure.

[0056] As shown in Figure 12 , specifically, the hoop stress (positive section vertical principal stress) of the segment lining member 1 under the combined action of the external and internal pressures is: ; Wherein: a is the inner radius; b is the outer radius; p i is the internal radial pressure; p o is the external radial pressure; t is the wall thickness; The circumferential stress (vertical principal stress of the normal section) of the segment lining member 1 under the combined action of external and internal pressure.

[0057] Based on the above formula, it can be seen that the annular stress of the lining segment component can be adjusted by adjusting the total tension of the steel strand and the injection pressure.

[0058] The circumferential strain of the inner and outer walls of the segment lining component 1 is measured by a distributed fiber optic sensor 10, and the average circumferential strain is calculated. The stress state of the ring is deduced based on the principles of elasticity. Specifically: ; ; : Circumferential stress; E: Elastic modulus of reinforced concrete segment; : Cross-sectional area; Circumferential strain on the outer wall of the tube segment; Circumferential strain of the inner wall of the tube segment; : Average circumferential strain of the tube segment.

[0059] During the experiment, it is necessary to first determine the internal stress σ of the segment lining structure required for the experiment. 目标值 and osmotic pressure p 目标值 Then, the test load is input based on the following process: (1) Based on the seepage water pressure and inner radial pressure p of the segment lining component to be studied. i Based on the principle of equality, the circumferential stress inside segment lining member 1 under internal pressure is obtained. (1) Vertical principal stress of the cross section); (2) Circumferential stress of the segment lining member 1 under the combined action of external and internal pressures that need to be studied. (Vertical principal stress of the cross section,) It should be equal to σ 目标值 ), and deduce the total tension F of the steel strand, and use the above p i The value of F is the initial value for loading, used to input p. i The values ​​of F and F cause the circumferential stress within the structure to reach σ. 目标值 (3) The structural stress σ derived from the strain obtained by the distributed optical fiber sensor and the target circumferential stress σ are compared. 目标值 Compare, such as with σ 目标值 If discrepancies exist, the value of F is further adjusted until the reading of the distributed fiber optic sensor matches the strain corresponding to the preset stress value (i.e., σ = σ). 目标值 ).

[0060] Step 3: Connect the positive terminal of the power supply to the anode component and connect the negative terminal of the power supply to the cathode component 7.

[0061] The steel bar 2 embedded in the concrete is used as an anode and is connected to a direct current stabilized power supply through an insulated wire. The positive pole of the direct current stabilized power supply is connected to the steel bar 2, and the negative pole is connected to a copper rod, thereby establishing a stable direct current electric field between the pipe lining component 1 and the copper rod. Under the action of the direct current electric field, anions (such as Cl - ) dissolved in the corrosive liquid migrate to the anode (steel bar 2). This process significantly accelerates the penetration speed of corrosive media such as chloride ions in the concrete and their enrichment on the surface of the steel bar 2, thereby accelerating the penetration: greatly shortening the time required for chloride ions to penetrate to the surface of the steel bar 2 and reach the critical concentration. Accelerating corrosion: directly accelerating the anodic electrochemical reaction of the steel bar 2 through electrochemical action, inducing and accelerating the corrosion of the steel bar 2.

[0062] Step 4, start the data acquisition module.

[0063] When the test reaches a certain stage, the electrode array 8 embedded in the concrete and the resistivity acquisition instrument electrically connected to the electrode array 8 are used to capture and analyze the seepage path, penetration depth, and leakage amount of the corrosive liquid in the pipe concrete in real time. Through the optical fiber sensor closely adhered to the surface of the steel bar 2 at key positions, the local strain mutation caused by the volume expansion of the corrosion product of the pipe lining component 1 is monitored in real time, and when the characteristic continuous strain growth is monitored and the influence of mechanical load is excluded, the starting point, development range, and corrosion degree of the steel bar 2 corrosion are accurately positioned and quantitatively evaluated. When the test reaches a certain time node, the internal water pressure and external radial pressure can be unloaded to a safe state in stages according to the preset program, and the internal water body is drained. Subsequently, the constraints of the first sealing cover 3 and the second sealing cover 4 on the pull rod are released, the device is disassembled, and the specified layer of the pipe ring (or arc-shaped pipe) is taken out as the research sample at this time node. The sample can be used for microstructure observation, penetration depth determination, material performance analysis, etc. After sampling, the remaining pipe rings and components can be reassembled according to the established assembly process by adjusting the extension length of the pull rod to adapt to the total height of the remaining assembled pipe, restoring the original sealing and load conditions, and continuing the test in the subsequent stage. Thus, the seawater penetration, structural deterioration, and failure process of the shield tunnel pipe lining under the combined action of different stress states and different seawater pressures are simulated.

[0064] The basic principles of the application are described above in conjunction with specific embodiments, but it should be noted that the advantages, advantages, effects, etc. mentioned in the application are only examples and not limitations, and these advantages, advantages, effects, etc. cannot be considered as the must-have of each embodiment of the application. In addition, the above specific details are only for the purpose of example and understanding, and are not limited to the application of the above specific details.

[0065] The block diagrams of the devices, apparatuses, equipment, systems referred to in the present application are only illustrative examples and are not intended to require or imply that the connection, arrangement, configuration must be as shown in the block diagrams. These devices, apparatuses, equipment, systems can be connected, arranged, configured in any manner as will be appreciated by those skilled in the art. Words such as "include", "contain", "have", and the like are open-ended words, mean "including but not limited to", and can be used interchangeably with each other. The words "or" and "and" used herein mean the word "and / or", and can be used interchangeably with each other, unless the context clearly indicates otherwise. The word "such as" used herein means the phrase "such as but not limited to", and can be used interchangeably with each other.

[0066] It should also be noted that in the devices, apparatuses and boxes of the present application, each component or each step can be disassembled and / or reassembled. These disassembly and / or reassembly should be considered as equivalent solutions of the present application.

[0067] The above description of the disclosed aspects is provided to enable any person skilled in the art to make or use the present application. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein can be applied to other aspects without departing from the scope of the present application. Thus, the present application is not intended to be limited to the aspects shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0068] It should be understood that the adjectives "first", "second", "third", "fourth", "fifth" and "sixth" used in the embodiments of the present application are only used for more clearly describing the technical solutions and cannot be used to limit the protection scope of the present application.

[0069] The above description has been given for the purpose of illustration and description. Furthermore, this description is not intended to limit the embodiments of the present application to the forms disclosed herein. Although a number of example aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, changes, additions and sub-combinations thereof.

Claims

1. A multi-field coupled test device for simulating the structural deterioration of an underwater shield tunnel, characterized in that, include: The segment lining components are arranged in a ring, and the segment lining components are cast from concrete and steel bars set in the concrete. The hoop force application module includes a force application component disposed on the outer periphery of the segment lining member; The injection module includes a first sealing cap that seals a first end of the segment lining member, a second sealing cap that seals a second end of the segment lining member, a connecting rod assembly that connects the first sealing cap and the second sealing cap, and a water injection pump. The first sealing cap is located on top of the second sealing cap and has an injection hole. Water-stopping elements are provided between the first sealing cap and the segment lining member, and between the second sealing cap and the segment lining member. The first sealing cap, the second sealing cap, and the segment lining member enclose a sealed cavity. The data acquisition module includes an electrode array embedded in concrete, a resistivity acquisition instrument electrically connected to the electrode array, a water pressure sensor, a component internal force sensor, and a data acquisition instrument used in conjunction with the component internal force sensor. During the experiment, corrosive liquid was injected into the sealed cavity through the injection hole, and the injection pump was pressurized based on a preset permeation water pressure. The pressurized corrosive liquid drove the corrosive ions inside to migrate into the concrete, thereby inducing steel corrosion and concrete deterioration. The water permeation state, stress state and water pressure value inside the sealed cavity were monitored in real time by the data acquisition module.

2. The multi-field coupled test device for simulating the structural deterioration of a submarine shield tunnel as described in claim 1, characterized in that, It also includes an electrochemical corrosion module, which includes a cathode coaxially arranged with the segment lining component and a power supply for conducting the anode and the cathode. The anode is formed by reinforcing steel bars. A DC electric field is applied between the anode and the cathode to drive the corrosion ions in the corrosive liquid to migrate directionally in the concrete, thereby accelerating the corrosion of the reinforcing steel bars and the deterioration of the concrete.

3. The multi-field coupled test device for simulating the structural deterioration of a submarine shield tunnel as described in claim 1, characterized in that, The linkage assembly consists of multiple telescopic rods.

4. The multi-field coupled test device for simulating the structural deterioration of a submarine shield tunnel as described in claim 1, characterized in that, The force-applying component includes a metal strand wound around the outer periphery of the segment lining member and a tensioning device for tensioning the metal strand.

5. The multi-field coupled test device for simulating the structural deterioration of a submarine shield tunnel as described in claim 1, characterized in that, The segment lining component is composed of multiple annular segments arranged along the axial direction of the segment lining component; or, the segment lining component is composed of multiple arc-shaped segments; or, the segment lining component is composed of a single annular segment.

6. The multi-field coupled test device for simulating the structural deterioration of an underwater shield tunnel as described in claim 5, characterized in that, The electrode array is embedded inside the concrete and is distributed in an array along the circumference of the segment lining component.

7. The multi-field coupled test device for simulating the structural deterioration of a submarine shield tunnel according to claim 1, characterized in that, The data acquisition module also includes distributed fiber optic sensors, which are arranged along the circumference of the segment lining component on the outer and inner peripheral walls of the segment lining component.

8. The multi-field coupled test device for simulating the structural deterioration of a submarine shield tunnel according to claim 2, characterized in that, The first sealing cover has a through hole, and the second sealing cover has a groove on the side facing the sealing cavity. The cathode component passes through the through hole and is embedded in the groove, wherein the axis of the through hole and the groove coincides with the axis of the segment lining component.

9. The multi-field coupled test device for simulating the structural deterioration of an underwater shield tunnel as described in claim 8, characterized in that, Both the first sealing cap and the second sealing cap are made of metal. Both the first sealing cap and the second sealing cap have an insulating layer on the side facing the sealing cavity, and an insulating seal is provided between the through hole and the cathode.

10. A multi-field coupled test method for simulating the structural deterioration of an undersea shield tunnel, applicable to the multi-field coupled test apparatus for simulating the structural deterioration of an undersea shield tunnel as described in any one of claims 1-9, and comprising: Step 1: Start the tensioning device and use the tensioning device to apply circumferential constraints to the segment lining member through the metal strands, and gradually increase the tension force according to the preset level until the uniform pressure on the outer peripheral wall of the segment lining member reaches the first preset value. Step 2: Start the water injection pump to inject corrosive liquid into the sealed cavity, and gradually pressurize the corrosive liquid inside the sealed cavity until the uniform water pressure on the inner peripheral wall of the segment lining component reaches the second preset value. Step 3: Connect the positive terminal of the power supply to the anode component and connect the negative terminal of the power supply to the cathode component. Step 4: Start the data acquisition module.

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