Device and method for long-term waterproofing durability test of shield segment sealing joint

Abstract

This invention discloses a test device and method for the long-term waterproof durability of shield tunnel segment sealing joints. It solves the problem that existing testing devices mainly focus on the sealing of the sealing components themselves, without addressing the waterproof performance of the joints. This invention ensures the accuracy of the test results. The specific solution is as follows: The test device for the long-term waterproof durability of shield tunnel segment sealing joints includes a detachably connected clamping component, a first mold, and a second mold. After the shield tunnel segment sealing component is inserted, a gap is formed between the first and second receiving components. A water inlet is provided in either the first or second mold, communicating with the gap. An infrared thermal imager is placed on the outside of the first or second mold. The infrared thermal imager acquires image information of the joints between the two shield tunnel segment sealing components. When the control unit determines that water seepage occurs at the joints between the two shield tunnel segment sealing components in the image acquired by the infrared thermal imager, it records the current value of the data acquisition unit.

Description

Technical Field

[0001] This invention relates to the field of shield tunnel technology, and in particular to a test device and method for the long-term waterproof durability of shield tunnel segment sealing joints. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] With the continuous development of urban underground space, shield tunnels have been widely used in important projects such as subways, river-crossing passages, and integrated utility tunnels. The long-term safe operation of shield tunnels is highly dependent on the waterproof performance of the segment joints. Once the waterproofing fails, it can easily lead to water leakage, structural corrosion, and even affect the normal operation of the tunnel. Therefore, joint waterproofing technology has always been a key research focus in shield tunneling projects.

[0004] In actual service, the waterproofing performance of tunnel segment joints is affected by a variety of factors. From the perspective of sealing material characteristics, commonly used composite rubber gaskets rely on high-pressure extrusion for sealing, resulting in a relatively large thickness that can easily lead to increased joint opening, posing a challenge to long-term waterproofing reliability. While water-swellable sealing strips offer good adhesion, they may develop micro-cracks after expansion, and their long-term durability remains to be verified. Simultaneously, the tunnel service environment is complex and variable, including varying water pressures and different water types (such as freshwater, seawater, and groundwater containing chemicals). These environmental factors accelerate the aging and performance degradation of sealing materials, posing a severe test to the long-term stability of the waterproofing system.

[0005] In summary, the core of waterproofing shield tunnels lies in ensuring that the sealing gaskets maintain sufficient contact pressure to resist water seepage throughout long-term service. Once the joint opening increases, the waterproofing effect will significantly decrease. However, current technology for testing the waterproofing durability of shield tunnel segments mainly focuses on the entire sealing component, without considering the waterproofing issue at the joint between two sealing components. The waterproofing issue at the joint is also of great significance for the development of related research. Moreover, simply filling the container with water and relying on the naked eye to observe whether there is any leakage is inaccurate. Furthermore, when the naked eye observes leakage, it means that the leakage has been going on for quite some time, which introduces a certain lag and affects the accuracy of the test results.

[0006] In addition, existing testing devices simply inject water and passively obtain test results: that is, after setting a fixed clamping force and constant water pressure, they wait for the gasket to fail naturally or leak over a long period of time. During the test, the operating conditions cannot be actively changed, nor can the real service environment such as water pressure fluctuations, joint dynamic deformation, and water quality alternation be simulated. This passive waiting testing method can only answer "whether it will leak under a certain fixed condition", but cannot actively study "under what dynamic conditions it will leak and how it will leak", which seriously limits the forward-looking and engineering guidance value of long-term durability research of sealing materials. Summary of the Invention

[0007] To address the shortcomings of existing technologies, the purpose of this invention is to provide a long-term waterproof durability testing device for the joints of shield tunnel segment seals. This device enables waterproof testing of the joints of shield tunnel segment seals, allowing for immediate detection of water seepage at the joints without delay, thus effectively ensuring the accuracy of the test results.

[0008] To achieve the above objectives, the present invention is implemented through the following technical solution: The long-term waterproof durability test device for shield tunnel segment sealing joints includes a detachably connected clamping component, a first mold, and a second mold. The first mold is placed on one side of the second mold, and the clamping component is placed on the side of the first mold away from the second mold. A first receiving component is provided on the side of the first mold, and a second receiving component is provided on the side of the second mold. The first and second receiving components are used to place the shield tunnel segment sealing components. After the shield tunnel segment sealing components are placed, a gap is formed between the first and second receiving components. A water injection port is provided in either the first or second mold, and the water injection port communicates with the gap. A switch is provided at the water injection port. Data acquisition units are provided in the first and second molds. An infrared thermal imager is provided on the outside of the first or second mold. The infrared thermal imager acquires image information of the joint between the two shield tunnel segment sealing components and sends it to the control unit. When the control unit determines that water seepage occurs at the joint between the two shield tunnel segment sealing components in the image acquired by the infrared thermal imager, it records the value of the data acquisition unit at the current moment.

[0009] As described above, in the shield tunnel segment sealing joint long-term waterproof durability test device, the control unit stores theoretical values ​​of different water injection volumes. The control unit is connected to the switch, and the control unit injects different water injection volumes into the test device by opening and closing the switch. A flow meter is installed at the water injection pipeline. The control unit obtains the actual value of the water injection volume into the test device based on the flow rate value obtained by the flow meter and the water injection time. When the actual value of the water injection volume is equal to the theoretical value of the water injection volume, the control unit controls the switch to close.

[0010] The shield tunnel segment sealing joint long-term waterproof durability test device described above uses a valve, needle valve, or peristaltic dripping component as the switch. A programmable booster pump is installed at the water injection pipeline.

[0011] As described above, in the long-term waterproof durability test device for the joint of the shield tunnel segment seal, the control unit is connected to the alarm unit. When the control unit determines that water seepage occurs at the joint of the two shield tunnel segment seals in the image acquired by the infrared thermal imager, it controls the alarm mechanism to sound an alarm. The data acquisition unit includes a pressure sensor disposed between the clamping member and the first mold and a displacement sensor disposed on the side of the first mold. The pressure sensor and the displacement sensor are respectively connected to the control unit separately.

[0012] The shield tunnel segment sealing joint long-term waterproof durability test device described above connects the clamping member, the first mold and the second mold with connecting bolts, or connects the clamping member to the force application mechanism. The clamping force can be adjusted by connecting bolts or force application mechanism. The setting position of the fastening bolts exceeds the setting of the first receiving member and the second receiving member. The second mold is equipped with a positioning pin, and the first mold is equipped with a positioning hole. The positioning pin can pass through the positioning hole.

[0013] As described above, the shield tunnel segment sealing joint long-term waterproof durability test device forms a water injection cavity between the first mold and the second mold after the first and second receiving parts are connected. The water injection port is connected to the water injection cavity. The first receiving part is embedded in the first mold, and the second receiving part is embedded in the second mold. The outer sides of the first receiving part and the second receiving part are in contact, and gaps are left on both the outer and inner sides between the first receiving part and the second receiving part. The first receiving member is detachable relative to the first mold, and the second receiving member is detachable relative to the second mold. The first receiving member can be fitted with multiple second receiving members, and the spacing between the inner side of different second receiving members and the first receiving member is different.

[0014] As described above, in the shield tunnel segment sealing joint long-term waterproof durability test device, the displacement sensor is located on the periphery of the first mold, the bottom of the displacement sensor is supported by the second mold, the pressure sensor is located on the periphery between the clamping member and the first mold, and the pressure sensor is placed above the shield tunnel segment sealing member.

[0015] As described above, the shield tunnel segment sealing joint long-term waterproof durability test device includes a clamping plate as the clamping component, a first mold as the first template with a pressure relief port, a second mold as the second template, a first receiving component with a first receiving groove, and a second receiving component with a second receiving groove.

[0016] Secondly, the present invention also provides a method for testing the long-term waterproof durability of the joints of shield tunnel segment seals, including the following: A detachable test device is set up, the seal to be tested is set up inside the test device, the test device is equipped with a water inlet, the water inlet is connected to the water inlet pipeline, a switch is set at the water inlet pipeline, and an infrared thermal imager is set up on one side of the second mold. The control unit stores theoretical values ​​for different water injection volumes, and controls the amount of water injected into the test device via a switch. The infrared thermal imager acquires image information of the joint between the two shield tunnel segments and sends it to the control unit. When the control unit determines that water seepage has occurred at the joint between the two shield tunnel segments in the image acquired by the infrared thermal imager, it records the data of the data acquisition unit at the current moment.

[0017] As described above, the test method for the long-term waterproof durability of shield tunnel segment sealing joints involves changing the injected solvent and conducting the test again after a set of shield tunnel segment sealing tests are completed. After the test of one set of shield tunnel segment seals was completed, the first and second molds were disassembled, another set of shield tunnel segment seals were replaced, and the test was conducted again.

[0018] The beneficial effects of the present invention are as follows: 1) The test device provided by this invention has a reasonable structure, including a first mold and a second mold. A first receiving member is set on one side of the first mold, and a second receiving member is set on one side of the second mold. The two receiving members are used to place shield tunnel segment seals. When the first receiving member and the second receiving member are connected, they form a connected shield tunnel segment seal, which realizes the waterproof test of the joint of the shield tunnel segment seal. The first mold is equipped with a water injection port to supply water into the test device. During the test, the data acquisition unit acquires relevant data, and the infrared thermal imager acquires image information of the joint of the two shield tunnel segment seals and sends it to the control unit. When the control unit determines that water seepage occurs at the joint of the two shield tunnel segment seals in the image acquired by the infrared thermal imager, it records the value of the data acquisition unit at the current moment. In this way, water seepage can be detected in time without human visual observation, so as to ensure that the data on the moment of water seepage is accurate.

[0019] 2) The test method provided by this invention stores theoretical values ​​of different water injection volumes in the control unit. The control unit actively changes the water injection volume through a switch to achieve adjustment under different working conditions. It considers the impact of changes in working conditions on the test results, changes the existing passive detection method to active detection, and actively studies under what dynamic conditions leakage will occur and how leakage will occur. Through the study of waterproofing test at the joint of sealing material, it has forward-looking and engineering guiding value for the long-term durability study of shield tunnel segment seals. Attached Figure Description

[0020] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0021] Figure 1 This is a schematic diagram of a test device for the long-term waterproof durability of shield tunnel segment sealing joints according to one or more embodiments of the present invention.

[0022] Figure 2 This is a schematic diagram of a section of the structure in the shield tunnel segment sealing joint long-term waterproof durability test device according to one or more embodiments of the present invention.

[0023] Figure 3 This is a schematic diagram of a portion of the structure of the shield tunnel segment sealing joint long-term waterproof durability test device according to one or more embodiments of the present invention.

[0024] Figure 4 This is a schematic diagram of the positioning pin and fastening bolt in the long-term waterproof durability test device for the joint of the shield tunnel segment seal according to one or more embodiments of the present invention.

[0025] Figure 5 This is a trend diagram of the contact stress-time variation of the composite rubber gasket in the long-term waterproof durability test method for the joint of the shield tunnel segment sealing component according to one or more embodiments of the present invention.

[0026] Figure 6 This is a trend diagram of the contact stress-time variation of the sealing strip that expands upon contact with water in the long-term waterproof durability test method for the joint of the shield tunnel segment sealing component according to one or more embodiments of the present invention.

[0027] Figure 7 This is a stress-strain relationship trend diagram of the composite rubber sealing gasket in the long-term waterproof durability test method for the joint of the shield tunnel segment sealing component according to one or more embodiments of the present invention.

[0028] The diagram exaggerates the spacing or dimensions between parts to show their positions; the diagram is for illustrative purposes only.

[0029] The components include: 1. Water pressure gauge; 2. Shield tunnel segment seal; 3. Liquid tank; 4. Pressure sensor; 5. Fastening bolt; 6. Water injection chamber; 7. Data acquisition device; 8. Infrared thermal imager; 9. Computer; 10. Water injection port; 11. Vent; 12. First mold; 13. Second mold; 14. First receiving part; 15. Second receiving part; 16. Positioning pin; 17. Nut; 18. Clamping part; 19. Displacement sensor. Detailed Implementation

[0030] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0031] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, unless otherwise expressly indicated by the invention, the singular form is also intended to include the plural form. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof. As described in the background section, existing testing devices mainly address the sealing issues of the seals themselves, without considering the waterproof performance of the seal joints. To address these technical issues, this invention proposes a long-term waterproof durability testing device for the joints of shield tunnel segment seals.

[0032] Example 1 In a typical embodiment of the present invention, reference is made to Figure 1 As shown, the long-term waterproof durability test device for shield tunnel segment sealing joints includes a detachably connected clamping member 18, a first mold 12, and a second mold 13. The first mold 12 is the upper mold, and the second mold 13 is the lower mold. The first mold 12 is placed above the second mold 13, and the clamping member 18 is placed above the first mold 12. A first receiving member 14 is provided on one side of the first mold 12, and a second receiving member 15 is provided on one side of the second mold 13. The first receiving member 14 and the second receiving member 15 are used to place the shield tunnel segment sealing member 2. The first mold is provided with a water injection port 10, which is connected to a water injection pipeline. A switch is provided at the water injection pipeline. Data acquisition form. The unit includes a pressure sensor 4 and a displacement sensor 19. The pressure sensor 4 is installed between the clamping component and the first mold 12, and the displacement sensor 19 is installed on the side of the first mold 12. The switch, pressure sensor 4, and displacement sensor 19 are each connected to the control unit separately. An infrared thermal imager 8 is installed on one side of the second mold 13. The infrared thermal imager 8 acquires image information of the joint between the two shield tunnel segments and sends it to the control unit. When the control unit determines that water seepage occurs at the joint between the two shield tunnel segments in the image acquired by the infrared thermal imager 8, it records the data of the pressure sensor 4 and the displacement sensor 19 at the current moment.

[0033] Specifically, the first mold 12 and the second mold 13 are both groove-shaped structural components, which are arranged opposite each other and have no gaps on the outer side after they are connected. The first receiving component 14 and the second receiving component 15 are respectively provided with grooves to accommodate the shield tunnel segment seal 2. The shape of the groove is the same as the shape of the shield tunnel segment seal 2. The clamping component 18 is a flat structural component, which simplifies the overall structure and forms a modular structure, making it convenient to build a complete test platform. The device has a reasonable structure and simple operation process. Only basic operations such as seal installation, clamping force application, and liquid injection need to be completed to carry out the test, which significantly reduces the complexity of the equipment and the difficulty of operation, and improves the testing efficiency.

[0034] It should be noted that, in order to achieve active control, the control unit stores theoretical values ​​for different water injection volumes. The control unit controls the amount of water injected into the test device through switches (such as valves). A flow meter is installed at the water injection pipeline. The control unit obtains the actual value of the water injection volume into the test device based on the flow rate value obtained by the flow meter and the water injection time (when the flow rate is constant: the actual value of the water injection volume = flow rate × time is used directly; when the flow rate changes with time: the flow rate needs to be integrated with respect to time, that is, the actual value of the water injection volume = ∫flow rate dt (integration with respect to time)). The flow rate is adjusted by the opening of the switch, and the water injection volume is changed by the length of the water injection time to achieve the required actual value of the water injection volume to meet the requirements of changing different operating conditions.

[0035] It should be noted that the purpose of water injection in the experiment is to actively simulate leakage behavior. The switch can be a valve, needle valve, or peristaltic dripping component. When the switch is a valve, the control unit can control the opening degree of the switch to achieve continuous injection of water at a set flow rate. In some examples, the switch is a needle valve or peristaltic dripping component to adjust the leakage parameters, which can be precisely set to a certain number of drops per minute (e.g., 1 drop / minute, 10 drops / minute). The leakage mode can also be adjusted: whether it is continuous leakage, intermittent leakage (e.g., leakage for 30 minutes every 12 hours), or phased incremental leakage (e.g., doubling the rate every 24 hours). The leakage start and end time can be set to start or stop at any time after the start of the experiment.

[0036] It is easy to understand that the control unit is connected to the alarm unit. When the control unit detects water seepage at the joint of the two shield tunnel segments in the image obtained by the infrared thermal imager, it controls the alarm mechanism to sound an alarm. The alarm unit is an alarm light or a buzzer so that the staff can discover it in time and stop the test in time to avoid wasting time. The control unit is connected to computer 9. The control unit is a PLC controller or other type of controller.

[0037] In this embodiment, reference Figure 4As shown, the fastening bolt 5 is positioned beyond the first receiving member 14 or the second receiving member 15. The clamping member 18, the first mold 12, and the second mold 13 are detachably connected by the fastening bolt 5 and the nut 17. The first mold 12 is subjected to a preset clamping force by the fastening bolt 5 at the four corners, and the pressure sensor 4 is used to monitor it in real time to establish a basic sealing test environment. The second mold 13 is provided with a positioning pin 16, and the first mold 12 is provided with a positioning hole. The positioning pin 16 can pass through the positioning hole to quickly position the connection between the first mold 12 and the second mold 13.

[0038] In some examples, the first mold 12 and the second mold 13 are connected, and the clamping member 18 is connected to the force-applying mechanism, which can be an existing hydraulic drive mechanism. The force-applying mechanism is connected to the control unit, which controls the force-applying mechanism to apply pressure to the clamping member in order to adjust the clamping force of the clamping member 18 acting on the first mold 12.

[0039] It should be explained that after the first receiving part 14 and the second receiving part 15 are connected, a water injection cavity is formed between the first mold 12 and the second mold 13. The water injection port 10 is connected to the water injection cavity 6. The first receiving part 14 is embedded in the first mold 12, and the second receiving part 15 is embedded in the second mold 13. There is a gap on the inner side of the first receiving part 14 and the second receiving part 15. In some examples, the first receiving member 14 is detachable relative to the first mold 12 and the second receiving member 15 is detachable relative to the second mold 13. The first receiving member 14 can be fitted with multiple second receiving members 15. The spacing between the inner side of different second receiving members 15 and the first receiving member 14 is different. By changing the different second receiving members 14, the size of the gap between the first receiving member 14 and the second receiving member 15 can be changed, thereby changing the speed at which water in the water injection chamber 6 enters the shield tunnel segment seal, so as to simulate the effect of the change in the amount of seepage water on the waterproof performance of the shield tunnel segment seal in actual working conditions.

[0040] It is easy to understand that the displacement sensor 19 is located on the periphery of the first mold 12, with one displacement sensor 19 on each side. The bottom of the displacement sensor 19 is supported by the second mold 13. The pressure sensor 19 is located on the periphery (at the four corners) between the clamping member 18 and the first mold 12. The pressure sensor 4 is placed above the shield segment seal 2 and is used to obtain the clamping force between the first mold 12 and the clamping member 18.

[0041] In some examples, the first receiving member 14 and the first mold 12 are either an integral structure or separate structures, as long as the first receiving member 14 can be embedded in the first mold 12. The second receiving member 15 and the second mold 13 are either an integral structure or separate structures, as long as the second receiving member 15 can be embedded in the second mold 13. The first receiving member 14 is provided with a first receiving groove, and the second receiving member 15 is provided with a second receiving groove. The first receiving groove and the second receiving groove are set as rectangular shapes and are formed by cutting. After the shield tunnel segment sealing member 2 (existing shield tunnel segment sealing gasket or water-swellable sealing strip) is assembled into the first receiving groove and the second receiving groove, a sealed water injection cavity 6 is formed. In addition, by replacing different types of shield tunnel segment seals (composite rubber gaskets / rainwater-expanding sealing strips) and testing them under the same clamping force, water pressure, and water quality conditions, stress-strain characteristic curves of different sealing materials are obtained, providing benchmark data for comparing the long-term waterproof durability performance of different materials. In some examples, the shield tunnel segment seal 2 is designed as a circular structure, which can further optimize the sealing boundary conditions and improve the applicability and accuracy of the test.

[0042] It should be explained that the water injection pipeline is connected to the liquid tank 3 via the pressurization pump 3, which is used to inject liquid into the water injection chamber. At the same time, the vent is opened to expel air to ensure uniform pressurization. The pressurization pump 3 is a programmable pressurization pump, which realizes dynamic programming control of water pressure. The system is no longer limited to constant water pressure loading. Through programming, it can automatically execute non-constant working conditions such as periodic fluctuating water pressure (simulating tidal changes), step impact water pressure (simulating instantaneous overpressure), and long-term drifting water pressure (simulating slow changes in groundwater level), thereby realistically reproducing the dynamic evolution characteristics of water pressure during tunnel service.

[0043] After the liquid is filled, the vent 11 is closed, and the pressure is continued to reach the set water pressure. The internal water pressure is monitored by the pressure gauge 18. Multiple liquid tanks 3 are set, and the composition of different liquid tanks 3 is different. This allows for changing different liquid tanks and the type of liquid in the water injection chamber 6, such as clean water, salt water, or other chemical solutions. After the air is removed, the pressure is increased to the set water pressure, which can accurately simulate the water pressure and water quality environment under different geological conditions and obtain accurate data on the long-term waterproof durability of the shield tunnel segment seals. In other words, the device supports a "wetting-drying-wetting" dry-wetting cycle mode. That is, first, liquid is introduced and pressurized to soak for a set time, then the device is opened, the liquid is drained, and hot air is introduced to dry it. Then, another liquid is switched to continue soaking. Overall, it can realistically simulate the complex underground chemical environment and the impact of alternating wet and dry conditions on the durability of the sealing material.

[0044] Pressure gauge 18 acquires the water pressure in injection chamber 6, while pressure sensor 4 acquires the clamping force between the clamping plate and the first mold. This continuous monitoring of water pressure and clamping force transmits the data in real time to the control unit, which is computer 9, enabling automated recording and analysis of the testing process. The system supports long-term uninterrupted operation and can capture the performance evolution patterns of the shield tunneling seals during long-term service.

[0045] Among them, the infrared thermal imager 8 enables non-contact continuous monitoring of leakage, which can not only accurately locate the location of micro-leakage, but also record the time history of leakage development, providing a visual basis for studying the long-term durability performance of sealing materials.

[0046] The test apparatus provided in this embodiment forms a shield tunnel segment seal 2 when the first receiving member 14 and the second receiving member 15 are connected. The first mold is equipped with a water injection port 10, through which water is supplied to the test apparatus. During the test, the pressure sensor 4 acquires relevant pressure data, the displacement sensor 4 acquires relevant displacement data, and the infrared thermal imager 8 acquires image information of the joint between the two shield tunnel segment seals 2 and sends it to the control unit. When the control unit determines that water seepage occurs at the joint between the two shield tunnel segment seals in the image acquired by the infrared thermal imager 8, it records the data of the pressure sensor and the displacement sensor at the current moment. In this way, water seepage can be detected in time without human visual observation, so as to ensure that the data on the moment of water seepage is accurate.

[0047] The test apparatus provided in this embodiment, based on the real-time monitoring signals of the infrared thermal imager 8, pressure sensor 4, and displacement sensor 19, allows the force-applying mechanism to remain inactive during initial water seepage, or the control unit to apply force to the clamping component through the force-applying mechanism to achieve self-recovery of the seal, thereby broadening the test path and upgrading this device from a traditional "passive detection device" to an "active simulation test platform." It can actively create, regulate, and record the performance response of the sealing material under various dynamic working conditions, providing a brand-new experimental paradigm for the research on the waterproof durability of shield tunnel segment seals.

[0048] Example 2 This embodiment discloses a test method for the long-term waterproof durability of the joints of shield tunnel segment seals, including the following: A detachable test device is set up. The test device contains the shield tunnel segment seal 2 to be tested. The test device is equipped with a water inlet 10, which is connected to the water inlet pipeline. A switch is set at the water inlet pipeline. The test device is equipped with a pressure sensor 4 and a displacement sensor 19. The switch, pressure sensor 4, and displacement sensor 19 are each connected to the control unit separately. An infrared thermal imager is set on one side of the second mold. The control unit stores theoretical values ​​for different water injection volumes, and controls the amount of water injected into the test device via a switch; The infrared thermal imager acquires image information of the joint between the two shield tunnel segments and sends it to the control unit. When the control unit determines that water seepage has occurred at the joint between the two shield tunnel segments in the image acquired by the infrared thermal imager 8, it records the data of the pressure sensor and displacement sensor at the current moment.

[0049] The control unit stores theoretical values ​​for different water injection volumes. The control unit actively changes the water injection volume through a switch to adjust for different operating conditions, taking into account the impact of changes in operating conditions on the test results.

[0050] When the shield tunnel segment seal 2 is a composite rubber gasket, through testing and reference... Figure 5 As shown, the trend of contact stress-time variation of composite rubber gasket can be obtained.

[0051] Analysis of the stress-time variation trend of composite rubber gaskets under different opening conditions (0 mm, 3 mm, 6 mm) reveals that the contact stress of the gasket exhibits a nonlinear trend of "rapid initial decay followed by gradual flattening" with the extension of service time. In the initial service period (approximately the first 5 years), the stress reduction under each condition is significant. As the compression increases (i.e., the opening decreases), the initial stress decay rate accelerates. This phenomenon may be related to the increased damage to the internal network structure of the rubber material under high compressive strain conditions, leading to more pronounced stress relaxation behavior. After entering the long-term service stage, the stress decay rate under each condition gradually decreases, and the curves tend to converge, indicating that the material gradually enters a relatively stable relaxation state during long-term use.

[0052] Based on the above curve morphology characteristics, a logarithmic decay model was used to conduct nonlinear regression analysis on the contact stress-time relationship under various working conditions, and the empirical formulas for stress evolution under different compression states were obtained as follows: Operating condition with 0 mm opening:

[0053] Operating condition with an opening of 3 mm:

[0054] Operating condition with an opening of 6 mm:

[0055] Parameter meaning: P is the contact stress of the composite rubber gasket, which is usually understood as MPa.

[0056] x represents the service period, which corresponds to "year" in the text.

[0057] ln(x) is the natural logarithm of time, used to describe the nonlinear decay of stress over time.

[0058] It should be noted that the above fitting results are only a mathematical approximation of the image trend based on limited experimental data. The selection of the logarithmic function form is mainly based on the curve morphology characteristics, and its parameter values ​​are directly related to the regression samples, but are not uniquely determined. Extrapolating the fitting formulas for each working condition to 100 years later, the estimated contact stress values ​​are all higher than the common design water pressure requirements (0.2 MPa), indicating that under the model assumptions, the gaskets under different compression states all have long-term waterproofing potential. However, factors such as material aging, temperature cycling, and water quality conditions in actual service environments are not included in this model. The above fitting formulas should be used as a theoretical reference under ideal conditions. In engineering applications, they need to be modified according to actual conditions and sufficient safety margins should be retained.

[0059] After a set of shield tunnel segment seal tests were completed, the injected solvent was changed, and the test was conducted again.

[0060] After the test of a set of shield tunnel segment seals was completed, the first and second molds were disassembled, another set of shield tunnel segment seals (water-swellable sealing strips) were replaced, and the test was conducted again.

[0061] refer to Figure 6 As shown in the curve of contact stress-time variation of the water-swellable sealing strip plotted based on experimental data, the contact stress exhibits an evolutionary characteristic of first rapidly increasing and then slowly decreasing with service time, eventually stabilizing. In the early stage of service (approximately the first 2.5 years), as water gradually penetrates, the volume expansion of the sealing strip leads to a rapid increase in compressive stress, with the stress rise rate showing a trend of first accelerating and then slowing down. When the water absorption approaches saturation, the viscoelastic relaxation effect of the polymer material gradually becomes dominant, and the contact stress decreases, with the decay rate gradually slowing down over time, eventually approaching a certain stable value.

[0062] To quantitatively describe the above evolutionary patterns, an empirical model was established based on the curve morphology characteristics using a piecewise function fitting method. The peak point... ( The year corresponds to the peak contact stress. ( ) serves as the dividing line, during the expansion enhancement period ( (The expansion of the sealing strip due to water absorption leads to increased stress) A third-order polynomial fitting was used during the stress relaxation period ( The stress decrease due to material viscoelastic relaxation is fitted using an exponential decay model, yielding the following expression: Expansion enhancement period:

[0063] Stress relaxation period:

[0064] In the formula, 0.5319 is the long-term asymptotic stress, which reflects the residual contact stress that the material can maintain after an infinitely long time; 0.3926 is the relaxation rate constant, which characterizes the rate of stress decay.

[0065] Parameter meaning: yes The contact stress at any given time can be expressed in MPa.

[0066] It refers to the service time, measured in years (a).

[0067] It is the peak point (peak time), which is a.

[0068] Peak contact stress, is MPa.

[0069] It should be noted that the above fitting results are only a mathematical approximation of the image trend based on limited experimental data. The model form and parameter values ​​are not unique, and the extrapolation prediction results have a certain degree of uncertainty. The estimated contact stress after 10 years of service is approximately 0.567 MPa. This value is higher than the long-term asymptotic stress, indicating that under the assumptions of the model, the sealing strip can still maintain a certain contact pressure over a 10-year timescale. In actual engineering applications, factors such as material aging and temperature cycling need to be considered to retain sufficient safety margin.

[0070] The contact stress evolution curves of the two sealing materials in the segment joints show significantly different morphological characteristics, which is mainly due to the essential differences in their functional positioning, initial state and loading mechanism in the joints.

[0071] When water-swellable sealing strips are applied to tunnel segment joints, their contact stress curve exhibits a typical "rise then fall" characteristic. In the initial stage of joint installation, the sealing strip is not yet in contact with water and is in a dry, contracted state, resulting in low initial contact stress. As groundwater gradually seeps into the joint, the sealing strip absorbs water and expands, generating continuously increasing compressive stress within the confined space of the joint. This expansion effect dominates in the early stages of service, manifesting as a rapid increase in stress. Once the water absorption approaches saturation, the expansion driving force weakens, and the viscoelastic relaxation effect of the sealing strip under continuous compressive stress gradually emerges. The stress begins to decay over time and eventually tends towards the long-term residual stress determined by the material's cross-linked network structure. This evolution process is essentially the result of the inverse relationship between the expansion and relaxation effects within the joint.

[0072] In contrast, the contact stress-time curves of composite rubber gaskets under different opening conditions exhibit a monotonically decreasing characteristic, without an initial upward phase. The fundamental reason for this is that these gaskets are already in a pre-compressed state during segment joint installation, and the initial contact stress is directly established by the initial closing pressure of the joint. During service, only stress relaxation remains as the dominant mechanism. It is noteworthy that the change in joint opening directly reflects the initial compression degree of the gasket: the smaller the opening, the tighter the joint closure, the greater the initial compression of the gasket, and the higher the initial strain experienced by the internal network structure of the material. This results in more significant chain segment damage and stress attenuation rates. Therefore, as the opening decreases from 6 mm to 0 mm, the initial stress attenuation rate accelerates, and the overall decrease in the curve is more pronounced.

[0073] In summary, the difference between the two types of curve shapes essentially reflects the different design philosophies of the segment joint sealing systems: water-swellable sealing strips rely on water seepage in the joint to trigger expansion and achieve self-sealing, and their stress evolution is jointly regulated by expansion and relaxation; while conventional sealing gaskets rely on initial compression during joint installation to establish sealing stress, and their long-term performance is mainly controlled by viscoelastic relaxation behavior. This comparative analysis shows that when predicting the long-term waterproof performance of segment joints, it is necessary to select an appropriate mathematical model based on the specific functional mechanism and initial state of the sealing material in the joint in order to accurately assess its long-term reliability under different service conditions.

[0074] Based on the stress-strain relationship graph of the composite rubber gasket, refer to Figure 7 As shown, the curve exhibits a "peak-shaped" characteristic of rising first and then falling, which can be divided into two stages for description: the first stage is a linear rising segment, reflecting the elastic response of the material in the initial stage of compression; the second stage is a linear falling segment, characterizing the softening behavior of the material after reaching its peak strength or the decrease in load-bearing capacity caused by contact nonlinearity.

[0075] The location of the peak point can be determined by visual estimation based on the scale relationship of the image coordinate axes (assuming the origin is 0): x-axis Approximately corresponding to the 3rd large scale mark, ordinate This corresponds approximately to the 7th major scale division; when the x-coordinate reaches approximately the 10th major scale division at the end of the curve, the y-coordinate decreases to the 5th major scale division. Based on this, the piecewise linear model is as follows: when Time (ascending phase): ,

[0076] when Time (descent segment): ,

[0077] Parameter meaning: It should be adapted to Stress at that time; Strain indicates the degree of material deformation; It is the peak strain; It is the peak stress; It is the slope of the rising segment, reflecting the stiffness of the material during the elastic loading stage; It is the slope of the descending segment, reflecting the softening rate after the peak; It is the stage of increasing elasticity; It is the softening or non-linear decline phase after the peak.

[0078] The parameters mentioned above are only mathematical approximations based on image proportions. The piecewise linear model form is chosen primarily based on curve morphology characteristics and is not a precise description of the material constitutive relationship. (Slope of the rising segment) This reflects the stiffness characteristics of the material during the elastic loading stage, with the peak point... This can be considered as the strength or yield strength of the material under this loading condition, with the slope of the descending segment being... A negative value represents the softening rate or stress relaxation degree of the material after reaching its peak. It should be noted that this model is only an empirical description of the image trend. For precise numerical fitting or engineering applications such as finite element analysis, it is recommended to recalibrate the model parameters based on measured data.

[0079] Existing equipment primarily tests the sealing performance of the gasket itself, neglecting testing the joints of the sealing components. Furthermore, existing testing devices can only passively wait for the gasket to fail naturally under prolonged pressure, making it impossible to predict the timing, location, and rate of leakage. Moreover, the leakage behavior of the same material under identical conditions often exhibits significant randomness, resulting in poor experimental repeatability and low data comparability. The method provided in this embodiment, through its overall structural design, achieves the following breakthroughs: ① Repeatability: Under the same parameter settings, the same leakage process can be accurately reproduced multiple times, which is convenient for standardized comparative testing of different sealing materials; ②Programmability: The time series and rate change curve of leakage can be designed arbitrarily according to research needs to simulate the entire process from initial micro-leakage to gradual aggravation and then to self-sealing recovery; ③ Early intervention capability: Without waiting for the material to fail naturally, leakage in the set mode can be actively stopped in the early stage of the experiment by tightening bolts or applying force, which greatly shortens the test cycle and obtains richer dynamic response data.

[0080] Moreover, researchers can pre-set a "working condition spectrum" containing multiple stages, with multiple parameters changing synchronously within each stage, thereby studying the synergistic degradation mechanism and failure boundary of sealing materials under the combined action of multiple factors in a complex environment.

[0081] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A test device for the long-term waterproof durability of shield tunnel segment sealing joints, characterized in that, The system includes a detachably connected clamping component, a first mold, and a second mold. The first mold is placed on one side of the second mold, and the clamping component is placed on the side of the first mold away from the second mold. A first receiving component is provided on the side of the first mold, and a second receiving component is provided on the side of the second mold. The first and second receiving components are used to place shield tunnel segment seals. After the shield tunnel segment seals are placed, a gap is formed between the first and second receiving components. A water inlet is provided in either the first or second mold, and the water inlet communicates with the gap. A switch is provided at the water inlet. Data acquisition units are provided in the first and second molds. An infrared thermal imager is provided on the outside of the first or second mold. The infrared thermal imager acquires image information of the joint between the two shield tunnel segment seals and sends it to the control unit. When the control unit determines that water seepage occurs at the joint between the two shield tunnel segment seals in the image acquired by the infrared thermal imager, it records the value of the data acquisition unit at the current moment.

2. The long-term waterproof durability test device for shield tunnel segment sealing joints according to claim 1, characterized in that, The control unit stores theoretical values ​​for different water injection volumes. The control unit is connected to the switch. The control unit injects different water injection volumes into the test device by opening and closing the switch. A flow meter is installed at the water injection pipeline. The control unit obtains the actual value of the water injection volume into the test device based on the flow rate value obtained by the flow meter and the water injection time. When the actual value of the water injection volume is equal to the theoretical value of the water injection volume, the control unit controls the switch to close.

3. The long-term waterproof durability test device for shield tunnel segment sealing joints according to claim 1, characterized in that, The switch is a valve, a needle valve, or a peristaltic dripping component; A programmable booster pump is installed at the water injection pipeline.

4. The long-term waterproof durability test device for shield tunnel segment sealing joints according to claim 1, characterized in that, The control unit is connected to the alarm unit. When the control unit determines that water seepage occurs at the joint of the sealing parts of the two shield tunnel segments in the image acquired by the infrared thermal imager, the control unit controls the alarm mechanism to sound an alarm. The data acquisition unit includes a pressure sensor disposed between the clamping member and the first mold and a displacement sensor disposed on the side of the first mold. The pressure sensor and the displacement sensor are respectively connected to the control unit separately.

5. The long-term waterproofing durability test device for a shield segment seal joint according to claim 1, characterized by, The connecting bolts connect the clamping member, the first mold, and the second mold, or the clamping member connects to the force-applying mechanism. The clamping force can be adjusted by the connecting bolts or the force-applying mechanism. The fastening bolts are positioned beyond the first and second receiving members. The second mold is equipped with a positioning pin, and the first mold is equipped with a positioning hole. The positioning pin can pass through the positioning hole.

6. The long-term waterproofing durability test device for a shield segment seal joint according to claim 1, characterized by, After the first receiving member and the second receiving member are connected, a water injection cavity is formed between the first mold and the second mold. The water injection port is connected to the water injection cavity. The first receiving member is embedded in the first mold, and the second receiving member is embedded in the second mold. Gaps are left on both the outer and inner sides between the first receiving member and the second receiving member. The first receiving member is detachable relative to the first mold, and the second receiving member is detachable relative to the second mold. The first receiving member can be fitted with multiple second receiving members, and the spacing between the inner side of different second receiving members and the first receiving member is different.

7. The long-term waterproofing durability test device for a shield segment seal joint according to claim 4, characterized by, The displacement sensor is located on the periphery of the first mold, and the bottom of the displacement sensor is supported by the second mold. The pressure sensor is located on the periphery between the clamping member and the first mold, and is positioned above the shield tunnel segment seal.

8. The long-term waterproofing durability test device for a shield segment seal joint according to claim 1, characterized by, The clamping component is a clamping plate, the first mold is a first template with a pressure relief port, the second mold is a second template, the first receiving component has a first receiving groove, and the second receiving component has a second receiving groove.

9. A method for testing the long-term waterproofing durability of a shield segment seal joint, characterized in that Includes the following: A detachable test device is set up, the seal to be tested is set up inside the test device, the test device is equipped with a water inlet, the water inlet is connected to the water inlet pipeline, a switch is set at the water inlet pipeline, and an infrared thermal imager is set up on one side of the second mold. The control unit stores theoretical values ​​for different water injection volumes, and controls the amount of water injected into the test device via a switch. The infrared thermal imager acquires image information of the joint between the two shield tunnel segments and sends it to the control unit. When the control unit determines that water seepage has occurred at the joint between the two shield tunnel segments in the image acquired by the infrared thermal imager, it records the data of the data acquisition unit at the current moment.

10. The method for long-term waterproof durability test of shield tunnel segment sealing joints according to claim 9, characterized in that, After a set of shield tunnel segment seal tests were completed, the injected solvent was changed and the test was conducted again. After the test of one set of shield tunnel segment seals was completed, the first and second molds were disassembled, another set of shield tunnel segment seals were replaced, and the test was conducted again.

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