Shield tunnel joint multi-sealing gasket waterproof performance test method based on cascade pressure transfer (CPT) mechanism

Abstract

The invention discloses a method for testing the waterproof performance of a plurality of sealing gaskets of a shield tunnel joint based on a cascade pressure transfer (CPT) mechanism, and aims to fill up the technical blank that the field of waterproof performance evaluation of a plurality of sealing gaskets of a shield tunnel joint with an ultra-large section is lack of a standardized and high-precision test method. The core of the method is as follows: firstly, decomposing a plurality of sealing gaskets into test modules capable of independently setting deformation, and accurately setting different joint opening and slab staggering quantity combinations for each sealing gasket; secondly, the pressure cavities of all the modules are connected in series through pressure transmission pipelines, and a cascade pressure transmission (CPT) waterway system is constructed; according to the system, the failure pressure of a preceding stage module can be transmitted to a backward stage module, so that the failure process of each sealing gasket is triggered and observed in sequence. According to the invention, the real deformation of the segment joint can be accurately simulated, the test flexibility and precision are improved, and a direct technical means is provided for researching the linkage failure rule of multiple sealing gaskets.

Description

Technical Field

[0001] This invention belongs to the field of shield tunnel engineering testing technology, specifically relating to a test method for the waterproof performance of multi-layer sealing gaskets in shield tunnel joints based on the cascaded pressure transfer (CPT) mechanism. Background Technology

[0002] Modern shield tunnel engineering is evolving towards extreme conditions such as ultra-large cross-sections and high water pressure, posing unprecedented challenges to its long-term waterproofing reliability. Currently, the engineering community generally uses single or double sealing gasket combinations to ensure the reliability of joint waterproofing. However, facing potentially more severe conditions in the future, relying solely on existing technological reserves may be insufficient. Therefore, exploring the use of waterproofing arrangements with more sealing gaskets (such as three or more) to enhance its ultimate bearing capacity has become a forward-looking research direction for ensuring the safety of mega-projects.

[0003] While exploring the application of multi-layer gaskets holds significant promise, a lack of scientific testing methods to evaluate the actual waterproofing effect and working mechanism of this novel arrangement remains a gap. Currently, the industry lacks a universally accepted testing procedure and specification to effectively verify its performance. This deficiency in verification means that our understanding of multi-layer gasket performance remains at the level of theoretical deduction, compromising the reliability of our conclusions and posing challenges to related engineering design and optimization efforts.

[0004] Simply following traditional testing methods can lead to misleading conclusions due to the limitations of their core assumptions. The theoretical basis of traditional testing methods is the assumption that segment joints remain parallel during deformation, resulting in equal compression of each gasket. However, in actual tunnel structures, under complex loads, joints more often undergo angular, non-parallel deformation, inevitably causing significant compression differences among the multiple gaskets. Because traditional methodologies cannot reproduce this crucial "unequal compression" scenario, their test results fail to reflect real-world conditions and are unsuitable for guiding the design of novel multi-gasket systems.

[0005] Therefore, developing a new experimental method that can fill the above gaps, and realistically simulate the differentiated stress states of multiple sealing gaskets and systematically reveal their linkage failure mechanisms, has irreplaceable theoretical value and significant engineering practical significance for promoting the transformation of new joint waterproofing technology from conceptual exploration to scientific application. Summary of the Invention

[0006] The purpose of this invention is to address the significant technological gap in the lack of applicable testing methods for the multi-layer sealing gasket waterproofing system unique to ultra-large cross-section shield tunnel engineering. This invention provides a testing method for the waterproofing performance of multi-layer sealing gaskets in shield tunnel joints based on the Cascaded Pressure Transfer (CPT) mechanism, thereby solving key problems of existing methods in terms of simulating real deformation, operational flexibility, and testing costs.

[0007] To achieve the above objectives, the present invention adopts the following technical solution.

[0008] A test method for the waterproof performance of multi-layer sealing gaskets in shield tunnel joints based on the cascaded pressure transfer (CPT) mechanism is proposed. The core idea of ​​this method is to decompose the multi-layer sealing gaskets, originally integrated onto a single steel plate, into at least two independent test module units for load-bearing and loading. The specific steps are as follows:

[0009] 1) Construction of the experimental system

[0010] The test system has at least two independent test module units, which are connected in series through pressure transmission pipelines to form a cascaded pressure transmission water system. Each test module unit includes an upper steel plate and a lower steel plate, with a pressure chamber formed between them. Each test module unit is equipped with a water inlet, a pressure gauge, a pressure transmission outlet, and a water-stop bolt connection hole. One end of the pressure transmission pipeline is connected to the pressure transmission outlet of the previous test module unit, and the other end is connected to the water inlet of the next test module unit. The pressure transmission outlet extends through the pressure chamber formed by the main test sealing gasket, auxiliary sealing gasket, upper steel plate, and lower steel plate. The water-stop bolt connection hole is sealed with a water-stop bolt.

[0011] A main test sealing gasket is installed between the upper and lower steel plates, and auxiliary sealing gaskets are installed in all units except the last test module unit.

[0012] 2) Decomposition of load-bearing capacity and differentiated deformation settings

[0013] Each test module unit is assigned and locked with a preset deformation condition, which includes the joint opening amount and / or the joint misalignment amount.

[0014] 3) Step-by-step loading and failure observation procedures

[0015] The test water pressure is applied to the first test module unit through the water inlet and gradually increased until the main test gasket it carries leaks and fails. The failure pressure is then transmitted to the subsequent test module units through the pressure transmission pipeline, and each main test gasket is loaded and failure is judged in turn, until the last main test gasket fails.

[0016] The test module unit also includes a slider, a hydraulic jack, and an adjusting and locking nut; the upper steel plate is slidably connected to the lower steel plate via the slider to adjust and lock the misalignment of the joint; the lower steel plate is connected to the support frame via the hydraulic jack to apply normal load; the hydraulic jack cooperates with the high-strength screw via the adjusting and locking nut to set and lock the joint opening.

[0017] The step-by-step loading and failure observation process also includes: using a water pressure gauge installed on each test module unit to monitor the pressure changes in each pressure chamber in real time, and recording the corresponding critical leakage pressure value when each of the main test gaskets fails due to leakage.

[0018] The main test gasket is installed in a symmetrical groove, which is the corresponding main test gasket groove on the upper and lower steel plates; the auxiliary sealing gasket is installed in an asymmetrical groove, which is the auxiliary sealing gasket groove on the lower steel plate.

[0019] The gradual increase in test water pressure during the step-by-step loading and failure observation process is carried out by gradually increasing and maintaining pressure.

[0020] The failure determination is specifically as follows: by observing a continuous decrease in the reading of the water pressure gauge, or by observing water leakage at the water-stop bolt connection hole of the next test module unit, it is determined that the previous main test gasket has failed due to leakage.

[0021] The termination condition of the method is the failure of the main test gasket of the last test module unit.

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] 1. A systematic test method is proposed: This invention proposes a test approach of "modular load-bearing, differentiated loading, and cascading failure", which provides a feasible test procedure for evaluating the synergistic waterproofing performance of multiple sealing gaskets in ultra-large cross-section shield tunnels, and helps to conduct scientific and detailed research on this kind of cutting-edge issue.

[0024] 2. Achieves accurate simulation of real deformation conditions: The method of this invention, through its core testing concept of "modular bearing and differentiated loading", allows for setting different opening and misalignment amounts for each sealing gasket, thereby realistically reproducing the non-equal deformation state of multiple sealing gaskets caused by non-parallel deformation of the segment joints. This overcomes the deformation simulation distortion problem caused by the use of integral steel plates in the background technology.

[0025] 3. Significantly improves the flexibility and economy of experimental research: The method of this invention transforms the test object from a large, bulky, and expensive monolithic steel plate into multiple small, independent modular plates. When different gaskets need to be studied, this method only requires replacing the corresponding modular plates, rather than the entire large device. This fundamentally solves the problems of poor structural adaptability and high cost existing in the background technology, and provides great convenience for systematic comparative studies.

[0026] 4. Significantly improved operational convenience and loading accuracy: The modular testing approach eliminates the need for inefficient bolt fastening methods traditionally relied upon for heavy steel plates. This method allows for the use of more efficient and precise loading and locking mechanisms (such as hydraulic jacks and locking nuts), which not only solves the operational inconvenience caused by bulky equipment in the prior art but also significantly improves the accuracy of loading and deformation control. Attached Figure Description

[0027] Figure 1 This is a schematic diagram illustrating the principle of the cascaded pressure transmission mechanism of the present invention.

[0028] Figure 2 This is a schematic diagram of the modular panel assembly structure in one embodiment of the present invention.

[0029] Figure 3 This is a schematic diagram of the assembly structure of the main test sealing gasket and the auxiliary sealing gasket in one embodiment of the present invention.

[0030] Figure 4 This is a schematic diagram illustrating the overall structure and function of one embodiment of the present invention.

[0031] Figure 5 This is a flowchart of the waterproof performance test method of the present invention.

[0032] The meanings of the markings in the attached diagram are as follows:

[0033] 1-Upper steel plate; 2-Lower steel plate; 3-Main test sealing gasket; 4-Auxiliary sealing washer; 5-Water inlet; 6-Water-stop bolt; 7-Pressure chamber between units A and B; 8-Pressure chamber between units B and C; 9-Pressure transmission pipeline; 10-Water pressure gauge; 11-Pressure transmission outlet; 12-Water-stop bolt connection hole; 13-Water pressure gauge connection hole; 14-Fixing bolt hole; 15-Main test sealing gasket groove; 16-Auxiliary sealing washer groove; 17-Slider; 18-High-strength screw; 19-Fixing nut; 20-Adjusting and locking nut; 21-Upper reaction plate; 22-Movable plate; 23-Support frame; 24-Hydraulic jack. Detailed implementation method.

[0034] To make the objectives, technical solutions, and advantages of this invention clearer, the following description will be provided in conjunction with the appendix. Figures 1 to 5The present invention will be described in further detail below. For clarity, for components with the same structure that appear repeatedly in the same drawing, the present invention will only label some of them, and the reference numerals for the remaining identical components can be found in the corresponding labeled components.

[0035] This invention proposes a test method for the waterproof performance of multi-layer sealing gaskets in shield tunnel joints based on the cascaded pressure transfer (CPT) mechanism. The principle of the test system is as follows: Figure 1 As shown, the complete experimental setup applying this experimental principle is as follows: Figure 4 As shown. In this preferred embodiment, the device includes three independently operating test module units, namely unit A, unit B, and unit C.

[0036] Reference Figure 1 This demonstrates the core idea of ​​the cascaded pressure transmission (CPT) mechanism of this invention. Each test unit consists of an upper steel plate 1 and a lower steel plate 2 joined together, with a main test gasket 3 (the primary test object) and an auxiliary sealing gasket 4 (for sealing) installed between them. Figure 1 As can be seen from the cross-sectional diagram, to ensure reliable pressure transmission step by step, this invention employs an asymmetrical groove design. Specifically, the main test sealing gasket 3 is constrained by the groove both above and below, while the auxiliary sealing gasket 4 is only constrained by the groove at its lower part. The specific assembly structure is as follows: Figure 3 The diagram further illustrates this. Water pressure enters the first test unit (unit A) through the water inlet 5 and acts on its main test gasket 3. When the main test gasket 3 of unit A fails due to excessive pressure, the leaking high-pressure water does not immediately terminate the entire test. Instead, it enters and fills the pressure chamber 7 between units A and B through the pressure transmission line 9, thereby establishing a new pressure in the chamber and then acting on the main test gasket 3 of the second test unit (unit B). Similarly, when the main test gasket 3 of unit B fails, pressure will enter the pressure chamber 8 between units B and C through another pressure transmission line 9, ultimately acting on the main test gasket 3 of unit C. A key technical setting is that unit C, as the last test unit, may not have an auxiliary sealing gasket 4. Therefore, the failure of its main test gasket 3 represents the final failure of the entire multi-seal system, marking the termination of the test. Throughout the process, the pressure gauge 10 is used to monitor pressure changes at each level, and the water-stop bolts 6 are used to seal unnecessary fluid channels. Through this design, the method enables the stepwise transmission of pressure and the sequential observation of the failure process of each gasket.

[0037] Reference Figure 2This demonstrates the modular plate assembly structure for implementing the Cascaded Pressure Transmission (CPT) mechanism, primarily showcasing the construction of the lower steel plate 2. Each lower steel plate 2 is pre-fabricated with a main test gasket groove 15 for accommodating the main test gasket 3 and an auxiliary sealing gasket groove 16 for accommodating the auxiliary sealing gasket 4. The lower steel plate 2 also features a series of fluid interfaces, including a water inlet 5 for connecting to an external water pressure supply system, a water pressure gauge connection hole 13 for connecting to a water pressure gauge 10, a water pressure bolt connection hole 12 for installing a water pressure bolt 6, and most importantly, a pressure transmission outlet 11 for connecting to the pressure transmission pipeline 9. The periphery of the lower steel plate 2 also has fixing bolt holes 14 for securing the entire specimen support assembly to the test device.

[0038] Reference Figure 3 The invention details the assembly structure of the main test gasket and auxiliary sealing gasket in a single test module. This structure mainly consists of a lower steel plate 2, an upper steel plate 1, a main test gasket 3, and an auxiliary sealing gasket 4. To ensure the reliable operation of the cascaded pressure transfer (CPT) mechanism, the invention employs a key asymmetric design in the groove design. Specifically, for the main test gasket 3, corresponding grooves are provided on both the lower steel plate 2 and the upper steel plate 1 to simulate the stress state of the gasket in actual engineering. For the auxiliary sealing gasket 4, which serves as an external seal, an auxiliary sealing gasket groove 16 is only provided on the lower steel plate 2; the corresponding surface of the upper steel plate 1 is flat and without grooves. This asymmetrical design ensures that when the upper and lower steel plates are laterally misaligned, the auxiliary sealing gasket 4 is not sheared or constrained by the upper groove, allowing it to deform more freely to maintain an effective seal. This ensures the reliability of the external sealing system under high misalignment and high water pressure, providing a guarantee for the smooth implementation of the cascaded pressure transfer (CPT) mechanism. A slider 17 is correspondingly provided at the bottom of the upper steel plate 1 for adjusting the lateral misalignment. Unit C, as the last test module unit, does not have an auxiliary sealing gasket groove 16 on its lower steel plate 2, and its steel plate size is smaller than the previous two module units.

[0039] Reference Figure 4This diagram illustrates the functional configuration of the test apparatus that supports the aforementioned modules and implements the method of the present invention. The entire apparatus is supported by a high-rigidity support frame 23. Each test module is equipped with a hydraulic jack 24 for independently applying normal loads. The hydraulic jack 24 lifts the movable plate 22 upwards and, through preset fixing bolts passing through fixing bolt holes 14, secures the movable plate 22 to the lower steel plate 2, thereby driving the lower steel plate 2 to move upwards and applying compressive force to the sealing gasket. The upper reaction plate 21 is connected to the support frame 23 by multiple high-strength screws 18 and locked by fixing nuts 19, forming a reaction system. After the sealing gasket is compressed to a predetermined deformation amount by the hydraulic jack 24, the adjusting and locking nuts 20 set on the high-strength screws 18 can be tightened until they contact the lower surface of the movable plate 22, thereby precisely mechanically locking the preset joint opening amount and ensuring the stability of the deformation state during the high-pressure test. The external water pressure supply system and displacement gauges used to measure displacement together constitute a complete testing environment.

[0040] Specific implementation steps of the method of the present invention

[0041] Reference Figure 5 The flowchart shown illustrates the specific operational procedure of the multi-layer sealing gasket waterproof performance test method of the present invention:

[0042] The first step is specimen preparation and installation. The main test gasket and auxiliary sealing gasket are fixed to the corresponding grooves on the lower steel plate of each test module using adhesives or other methods, and the modules are then assembled. Specifically, for the test unit designated as the last to be tested, only the main test gasket needs to be installed, without the auxiliary sealing gasket.

[0043] The second step is to set differentiated deformation conditions. Based on the experimental objectives, different combinations of joint opening and misalignment are set for different test units using independent loading and adjustment mechanisms for each module. The set deformation states are then mechanically locked to simulate the non-uniform deformation states that may occur in tunnel joints in actual engineering.

[0044] The third step is to connect the CPT water system. Following the preset pressure transmission path, connect each module unit in series via pressure transmission pipelines, and connect the external water pressure supply system and each pressure gauge. Slowly fill the entire pipeline system with water, and vent air through the air vents of each unit until the system is confirmed to be full of water and free of residual air. Then, close all air vents and unnecessary fluid passages.

[0045] The fourth step is to implement the first stage of loading and data acquisition. The water pressure supply system is activated to apply water pressure to the pressure chamber of the first test unit. Preferably, the water pressure is applied in stages, for example, with each pressure increment being a preset value and each stage held for a preset time. During this period, the corresponding water pressure gauge readings are closely monitored.

[0046] Step 5: Failure detection and pressure transfer. When the water pressure gauge reading becomes unsustainable and continues to decline, or when continuous leakage is observed in the next module, the gasket is determined to have failed, and the pressure at this point is recorded as its critical leakage pressure. At this time, according to the cascaded pressure transfer (CPT) mechanism, the leaking pressure will be automatically transferred to the next test unit.

[0047] Step 6: Implement subsequent loading and testing. Continue operating the water pressure supply system to continuously increase the water pressure throughout the connected water circuit. At this time, the pressure will be applied to the main test gasket of the second test unit until it leaks, and its critical pressure is recorded. Repeat this process until the main test gasket of the last test unit (i.e., the one without auxiliary sealing gaskets) fails, at which point the test is terminated.

[0048] Step 7: Data Analysis. After the test, by comprehensively analyzing the critical leakage pressure and pressure-time history curves of each sealing gasket under different preset deformation conditions, the synergistic waterproofing performance and stepwise failure mechanism of the multi-sealing gasket system can be thoroughly evaluated.

Claims

1. A test method for the waterproof performance of multi-layer sealing gaskets in shield tunnel joints based on the cascaded pressure transfer (CPT) mechanism, characterized in that, Includes the following steps: 1) Construction of the experimental system The test system has at least two independent test module units, which are connected in series through a pressure transmission pipeline (9) to form a cascaded pressure transmission water system. Each test module unit includes an upper steel plate (1) and a lower steel plate (2), and a pressure chamber is formed between the upper steel plate (1) and the lower steel plate (2). Each test module unit is provided with a water inlet (5), a water pressure gauge (10), a pressure transmission outlet (11), and a water-stop bolt connection hole (12). One end of the pressure transmission pipeline (9) is connected to the pressure transmission outlet (11) of the previous test module unit, and the other end of the pressure transmission pipeline (9) is connected to the water inlet (5) of the next test module unit. The pressure transmission outlet (11) extends through to the pressure chamber formed by the main test sealing gasket (3), the auxiliary sealing gasket (4), the upper steel plate (1), and the lower steel plate (2). The water-stop bolt connection hole (12) is sealed with a water-stop bolt (6). A main test sealing gasket (3) is installed between the upper steel plate (1) and the lower steel plate (2), and auxiliary sealing gaskets (4) are installed in the remaining units except for the last test module unit. 2) Decomposition of load-bearing capacity and differentiated deformation settings Each test module unit is assigned and locked with a preset deformation condition, which includes the joint opening amount and / or the joint misalignment amount. 3) Step-by-step loading and failure observation procedures The test water pressure is applied to the first test module unit through the water inlet (5) and gradually increased until the main test gasket (3) it carries leaks and fails. The failure pressure is transmitted to the subsequent test module units through the pressure transmission pipeline (9) and each main test gasket (3) is loaded and failure is judged in turn until the last main test gasket (3) fails.

2. The method according to claim 1, characterized in that, The test module unit also includes a slider (17), a hydraulic jack (24), and an adjusting and locking nut (20); the upper steel plate (1) is slidably connected to the lower steel plate (2) through the slider (17) to adjust and lock the misalignment of the joint; the lower steel plate (2) is connected to the hydraulic jack (24) through the movable plate (22), and the hydraulic jack (24) is set on the base of the support frame (23) to apply normal load; the joint opening is set by moving the adjusting and locking nut (20) along the high-strength screw (18) and locking the position of the movable plate (22).

3. The method according to claim 1, characterized in that, The step-by-step loading and failure observation steps also include: using a water pressure gauge (10) set on each test module unit to monitor the pressure change in each pressure chamber in real time, and recording the corresponding critical leakage pressure value when each of the main test gaskets (3) fails to leak.

4. The method according to claim 1, characterized in that, The main test gasket (3) is installed in a symmetrical groove, which is the corresponding main test gasket groove (15) on the upper steel plate (1) and the lower steel plate (2); the auxiliary sealing gasket (4) is installed in an asymmetrical groove, which is the auxiliary sealing gasket groove (16) on the lower steel plate (2).

5. The method according to claim 1, characterized in that, The gradual increase in test water pressure during the step-by-step loading and failure observation process is carried out by gradually increasing and maintaining pressure.

6. The method according to claim 1, characterized in that, The failure determination is carried out in the following way: by observing that the reading of the water pressure gauge (10) drops continuously and cannot be maintained, or by observing that there is water leakage at the water stop bolt connection hole (12) of the next test module unit, it is determined that the previous main test gasket (3) has failed due to leakage.

7. The method according to claim 1, characterized in that, The termination condition of the method is the failure of the main test gasket (3) of the last test module unit.

Images