Internal water pressure or low vacuum shield tunnel structure performance test device and method

Abstract

The invention discloses an internal water pressure or low vacuum shield tunnel structure performance test device and method. The device comprises a shield pipe section, a steel outer support, a hydraulic bag, a steel inner support, a cover plate, a sealing support and a connector. The hydraulic bag applies continuous distribution pressure to the outer side of the pipe section to simulate external water and soil load; the steel inner support and the inner wall of the pipe section form a cavity, and two ends of the steel inner support are sealed by the cover plate and the sealing support respectively to form a closed cavity; the connector can inject water into the cavity to establish positive pressure or exhaust air to establish negative pressure, and the inner side inner pressure or low vacuum working condition is achieved. The same device can complete the structural performance test under the action of outer side continuous loading and inner side positive / negative pressure coupling, the loading condition is continuous, the sealing is reliable, and the working condition switching is convenient.

Description

Technical Field

[0001] This invention relates to a test device and method for the structural performance of shield tunnels under internal water pressure or low vacuum, belonging to the technical field of test technology for shield tunnel segment lining structures. Background Technology

[0002] Shield tunnels have a wide range of applications, and the shield tunneling method offers advantages such as high speed and minimal impact on the surrounding environment. In urban subways and power or energy transmission tunnels in soft soil strata, the vast majority are constructed using the shield tunneling method. In recent years, the application areas of shield tunnels have continued to expand, with applications in water conveyance, drainage, or water storage tunnels. Furthermore, the use of shield tunnels in future low-vacuum maglev tunnels has proven to be a feasible structural type. Unlike traditional subway, power, or energy transmission tunnels, which only bear external water and soil loads, water conveyance, drainage, or water storage tunnels often experience high water pressure internally. Low-vacuum maglev tunnels, however, generate negative pressure due to internal vacuum, resulting in significantly different internal water pressure or structural stress characteristics compared to traditional urban subway, power, or energy transmission shield tunnels.

[0003] Testing is a crucial method for obtaining the structural performance of maglev shield tunnels under internal water pressure or low vacuum conditions. However, current testing methods for internal water pressure shield tunnels primarily employ intermittent loading with jacks on both the inner and outer sides of the segment rings. This approach fails to accurately reflect the mechanical properties of the tunnel structure under internal water pressure and continuous external soil and water loads. Furthermore, there are currently no corresponding testing techniques for low vacuum maglev shield tunnels. The main reason for the difficulty in accurately conducting performance tests on internal water pressure or low vacuum maglev shield tunnel structures is the presence of internal water pressure or low vacuum within the tunnel. Existing testing methods cannot create a sealed cavity within the tunnel structure to maintain the internal water pressure or vacuum state. Summary of the Invention

[0004] The present invention provides a test device and method for testing the structural performance of shield tunnels under internal water pressure or low vacuum in order to solve the problems existing in the prior art.

[0005] The technical solutions adopted in this invention are as follows:

[0006] A test device for the structural performance of shield tunnels under internal water pressure or low vacuum, comprising:

[0007] Shield tunnel segment;

[0008] The steel outer support is located on the outside of the shield tunnel section.

[0009] Hydraulic bladders, located between the steel outer side and the shield tunnel segment, are used to apply continuous distributed pressure to the shield tunnel segment to simulate external water and soil loads.

[0010] The steel inner wall is located inside the shield tunnel section, and a cavity is formed between the outer wall of the steel inner wall and the inner wall of the shield tunnel section.

[0011] The cover plate is fixed and pressed against the corresponding end face of the shield tunnel segment to seal the upper port of the cavity;

[0012] The sealing support supports the tunnel boring machine section and seals the lower end of the cavity, making the cavity a closed cavity with both ends closed in the axial direction.

[0013] An interface, connected to the sealed cavity, is used to inject fluid into the sealed cavity to establish positive pressure inside the shield tunnel section, or to extract gas from the sealed cavity to establish negative pressure inside the shield tunnel section.

[0014] Furthermore, the sealing support is a concrete base, with an annular groove opened on the upper surface of the concrete base. An elastic sealing element is laid in the annular groove, and the shield tunnel section and the steel inner support are both placed on the elastic sealing element. After being compressed, the elastic sealing element fills and seals the lower port of the cavity.

[0015] Furthermore, multiple hydraulic bladders are evenly distributed along the circumference, and each hydraulic bladder can be pressurized independently.

[0016] Furthermore, both the outer and inner steel supports are annular components, and the shield tunnel section, the outer steel support, and the inner steel support are arranged coaxially.

[0017] Furthermore, a support platform is provided on the outside of the steel inner wall, and a fixed column is provided on the support platform. The cover plate is inserted into the fixed column, and a nut is threaded onto the fixed column.

[0018] Furthermore, the cover plate simultaneously presses against the end face of the shield tunnel section, and an elastic sealant is provided at the contact points between the cover plate and the shield tunnel section and the steel inner wall.

[0019] Furthermore, the interface is connected to a water pump for injecting water into the sealed cavity to establish positive pressure.

[0020] Furthermore, the interface is connected to a vacuum pump for extracting gas from the sealed cavity to establish negative pressure.

[0021] Furthermore, after the vacuum pump is activated, the absolute pressure inside the sealed cavity is maintained at 1×10⁻⁶. 2 Pa ~ 1×10 5 Low vacuum range of Pa.

[0022] This invention also discloses a test method for a test device for the structural performance of shield tunnels under internal water pressure or low vacuum, comprising the following steps:

[0023] (a) The shield tunnel segment is placed on a sealing support, so that the sealing support forms a seal on the lower end of the shield tunnel segment;

[0024] (b) A steel outer abutment is installed on the outside of the shield tunnel segment, and a hydraulic bladder is arranged between the steel outer abutment and the shield tunnel segment;

[0025] (c) A steel inner abutment is provided inside the shield tunnel section, so that a cavity is formed between the outer wall of the steel inner abutment and the inner wall of the shield tunnel section;

[0026] (d) Fix the cover plate to the inner steel and press it against the corresponding end face of the shield tunnel section to seal the upper port of the cavity, thereby forming a closed cavity with both ends closed in the axial direction;

[0027] (e) Activate the hydraulic bladders to apply continuously distributed pressure to the outer wall of the shield tunnel segment, wherein the load applied by any one of the hydraulic bladders is calculated according to the following formula:

[0028] ,

[0029] in:

[0030] P represents the vertical soil and water load, measured in MPa.

[0031] P n1 and P n2 For the first The horizontal soil and water load corresponding to the two ends of each hydraulic bladder is expressed in MPa.

[0032] θ n1 and θ n2 For the first The central angles between the two ends of each hydraulic bladder and the center line of the arch are expressed in degrees.

[0033] (f) Injecting fluid into the sealed cavity through the interface to establish positive pressure inside the shield tunnel section, or extracting gas from the sealed cavity to establish negative pressure inside the shield tunnel section;

[0034] (g) By applying the load in step (e), the external water and soil load is simulated and works together with the internal pressure in step (f) to complete the coupled loading test.

[0035] The present invention has the following beneficial effects:

[0036] (1) By forming a sealed cavity on the inside and connecting the interface, positive or negative pressure can be continuously maintained inside the tube segment, which is superimposed with the continuous distributed load of the hydraulic bladder on the outside, realizing the one-time loading of the "external pressure + internal pressure / negative pressure" coupled working condition, and the test conditions are closer to the actual operating state.

[0037] (2) Hydraulic bladders are used instead of traditional intermittent jacks. The external load is continuously adjustable, avoiding the use of a large number of jacks. The equipment layout and disassembly time is shortened, and the test cost is reduced.

[0038] (3) Both the sealing support and the cover plate adopt the structure of "rigid compression + elastic sealing element", which can maintain the end face sealing during the deformation of the tube segment, reduce the risk of leakage, and improve the stability of the test and the repeatability of data.

[0039] (4) The same set of equipment can cover both internal water pressure and low vacuum conditions without replacing core components, saving repeated investment and facilitating subsequent expansion to other internal and external pressure difference combination tests. Attached Figure Description

[0040] Figure 1 This is a structural diagram of the test device for the internal water pressure or low vacuum shield tunnel structure performance of the present invention.

[0041] Figure 2 In order to be in Figure 1 The structural diagram is based on the removal of the steel outer frame.

[0042] Figure 3 In order to be in Figure 2 The structural diagram shows the removal of the shield tunnel section and the upward movement of the cover plate.

[0043] Figure 4 This is a structural diagram of a sealed support.

[0044] Figure 5 This is a structural diagram showing the removal of the hydraulic bladder located on the outer perimeter of the steel structure, near the rear.

[0045] Figure 6 This is a schematic cross-sectional view of the test device for the structural performance of shield tunnels with internal water pressure or low vacuum according to the present invention.

[0046] Figure 7 A schematic diagram illustrating the application of load to the hydraulic bladder.

[0047] in:

[0048] 1. Shield tunnel segment; 2. Steel outer frame; 3. Hydraulic bladder;

[0049] 4. Steel inner support; 41. Support platform;

[0050] 5. Cover plate;

[0051] 6. Sealing support; 61. Elastic seal;

[0052] 7. Interface;

[0053] 100. Cavity. Detailed Implementation

[0054] The invention will now be further described with reference to the accompanying drawings.

[0055] like Figure 1 , Figure 2 as well as Figure 6The present invention provides a test device for the structural performance of shield tunnels under internal water pressure or low vacuum, comprising a shield tunnel section 1, a steel outer support 2, a hydraulic bladder 3, a steel inner support 4, a cover plate 5, a sealing support 6, and an interface 7.

[0056] First, a sealed support 6 is installed on the concrete surface of the test site. For example... Figure 4 As shown, the sealing support 6 is a concrete base with an annular groove on its upper surface. The inner diameter of the annular groove is larger than the outer diameter of the shield tunnel segment 1 to avoid restricting the free deformation of the segment during loading. An elastic seal 61 is laid inside the annular groove. In this embodiment, the elastic seal 61 is made of EPDM rubber. This elastic seal 61 has good compression resilience and sealing performance, and can maintain an effective seal at the lower end of the shield tunnel segment 1 even when it is subjected to stress and deformation.

[0057] Subsequently, shield tunnel segment 1 (usually composed of multiple precast concrete segments assembled into a ring) is placed on the elastic seal 61, such as... Figure 2 As shown. Ensure that the bottom of the shield tunnel segment 1 is fully in contact with the EPDM rubber pad. At this time, the elastic seal 61 initially bears the weight of the shield tunnel segment 1 and forms an initial seal.

[0058] Next, a circular steel outer abutment 2 is coaxially installed on the outside of the shield tunnel segment 1, and multiple hydraulic bladders 3 are evenly distributed along the circumference in the annular gap between the steel outer abutment 2 and the shield tunnel segment 1 (e.g., Figure 5 The hydraulic bladders are made of rubber, and during testing, each bladder provides a pressure of 0.5-0.9 MPa. Each hydraulic bladder 3 can be pressurized independently. By adjusting the pressure of hydraulic bladders 3 at different positions, non-uniform soil and water loads can be simulated; if a uniform external load needs to be simulated, each hydraulic bladder 3 applies the same pressure. The continuous distributed pressure applied by the hydraulic bladders 3 more realistically reflects the external soil and water effects experienced by actual tunnels, overcoming the discontinuity defects of traditional jack-top loading.

[0059] At the same time, a circular steel inner support 4 (such as) is coaxially installed on the inner side of shield tunnel section 1. Figure 3 and Figure 6 As shown), the inner steel support 4 is also a circular component, coaxially arranged with the shield tunnel section 1 and the outer steel support 2 to ensure balanced force distribution throughout the device. An annular cavity 100 is formed between the outer wall of the inner steel support 4 and the inner wall of the shield tunnel section 1. This cavity 100 is the core area for establishing internal water pressure or a low vacuum state. To facilitate the fixing of the cover plate 5, a support platform 41 is provided on the outside of the inner steel support 4, and vertical fixing columns (such as...) are welded onto the support platform 41. Figure 3 (As shown).

[0060] The cover plate 5 is an annular plate that is adapted to the end face size of the shield tunnel segment 1. During installation, the corresponding position of the cover plate 5 is aligned with the fixing column on the support platform 41, so that the fixing column passes through the pre-set through hole on the cover plate 5. Then, a nut is threaded to the upper end of each fixing column (and a sealing gasket is set accordingly, or an elastic sealant is provided around the nut to ensure a seal). By tightening the nut, the cover plate 5 is pressed tightly against the upper end face of the shield tunnel segment 1, and at the same time, the inner side of the cover plate 5 is in contact with the upper end face of the steel inner pad 4.

[0061] To ensure the sealing performance of the sealed cavity, elastic sealant is applied to the contact area between the end face of the cover plate 5 and the shield tunnel section 1, and to the contact area between the cover plate 5 and the upper end face of the steel inner support 4. In this embodiment, the elastic sealant is silicone sealant or polyurethane sealant. At the same time, elastic sealant is also applied to the contact area between the lower end of the steel inner support 4 and the elastic sealing element 61. Through the dual structure of "rigid compression + elastic sealing", a sealed cavity with both ends closed in the axial direction is formed between the steel inner support 4, the shield tunnel section 1, the cover plate 5 and the sealing support 6. Even if the shield tunnel section 1 deforms later, the elastic sealing element 61 and the elastic sealant can still fill the deformation gap and maintain the sealing state of the cavity.

[0062] The inner steel support 4 has a reserved interface 7. The interface 7 penetrates the wall of the inner steel support 4 and is directly connected to the inner sealed cavity. By switching the external equipment connected to the interface 7, the two test conditions can be switched.

[0063] When it is necessary to simulate the internal water pressure condition, the interface 7 is connected to the water pump and the booster pump in sequence through the pipeline. First, the outer hydraulic bladder 3 is pressurized. By adjusting the pressure of each independent hydraulic bladder 3, the water and soil loads with different distribution states on the outside of the shield tunnel segment 1 are simulated. Then, clean water is injected into the sealed cavity through the water pump until the cavity is completely filled and there are no air bubbles left. Then, the booster pump is started to gradually increase the pressure in the sealed cavity until the internal water pressure value required for the test is reached. Then, the mechanical performance of the shield tunnel segment 1 under the coupled action of "continuous water and soil load on the outside + internal water pressure on the inside" is tested.

[0064] When simulating low-vacuum conditions, interface 7 is connected to the vacuum pump via a sealed pipe. A continuously distributed load is applied through the hydraulic bladder 3 located inside the steel outer shell 2 to simulate the action of soil and water in the strata. Then, after starting the vacuum pump, air is continuously extracted from the sealed cavity, gradually reducing the absolute pressure inside the cavity to 1×10⁻⁶. 2 Pa ~ 1×10 5 The low vacuum range of Pa was used to evaluate the structural performance of shield tunnel segment 1 under the coupled condition of "outer soil and water load + inner low vacuum negative pressure".

[0065] Throughout the test, because the outer steel support 2 and the inner steel support 4 are arranged coaxially with the shield tunnel section 1, and the hydraulic bladder 3 is evenly distributed around the circumference and pressurized independently, it can accurately simulate external loads with different distribution forms.

[0066] The sealed inner cavity, protected by both the elastic sealant 61 and the elastic sealant, effectively prevents internal water pressure leakage or low vacuum failure, ensuring stable and controllable test conditions. The same device can be used to test both internal water pressure and low vacuum conditions by switching external equipment connected via interface 7, eliminating the need to replace core components such as the outer steel support 2 and the inner steel support 4, significantly improving testing efficiency and reducing equipment investment costs.

[0067] Combination Figure 7 The test method of the present invention is as follows:

[0068] (a) The shield tunnel segment 1 is placed on the sealing support 6, so that the sealing support 6 forms a seal on the lower port of the shield tunnel segment 1;

[0069] (b) A steel outer support 2 is provided on the outside of the shield tunnel section 1, and a hydraulic bladder 3 is arranged between the steel outer support 2 and the shield tunnel section 1;

[0070] (c) A steel inner wall 4 is provided inside the shield tunnel section 1, so that a cavity is formed between the outer wall of the steel inner wall 4 and the inner wall of the shield tunnel section 1.

[0071] (d) Fix the cover plate 5 to the steel inner pad 4 and press it against the corresponding end face of the shield tunnel section 1 to seal the upper port of the cavity, thereby forming a sealed cavity with both ends closed in the axial direction.

[0072] (e) Activate the hydraulic bladder 3 to apply continuously distributed pressure to the outer wall of the shield tunnel segment 1, wherein the load applied by any one hydraulic bladder is calculated according to the following formula:

[0073] ,

[0074] in:

[0075] P represents the vertical soil and water load, measured in MPa.

[0076] P n1 and P n2 For the first The horizontal soil and water load corresponding to the two ends of each hydraulic bladder is expressed in MPa.

[0077] θ n1 and θ n2 For the first The central angles between the two ends of each hydraulic bladder and the center line of the arch are expressed in degrees.

[0078] (f) Inject fluid into the sealed cavity through interface 7 to establish positive pressure inside the shield tunnel section 1, or extract gas from the sealed cavity to establish negative pressure inside the shield tunnel section 1.

[0079] (g) By applying the load in step (e), the external water and soil load is simulated and works together with the internal pressure in step (f) to complete the coupled loading test.

[0080] The above description is merely a specific implementation process of the present invention. In practical applications, those skilled in the art can adjust the number of hydraulic bladders, pressurization accuracy, and pressure parameters of the sealed cavity according to experimental requirements. All such adjustments are within the protection scope of the present invention.

Claims

1. A test device for the structural performance of shield tunnels under internal water pressure or low vacuum, characterized in that: include Shield tunnel segment (1); The steel outer side (2) is located on the outside of the shield tunnel section (1); Hydraulic bladder (3) is located between the steel outer wall (2) and the shield tunnel section (1) to apply continuous distributed pressure to the shield tunnel section (1) to simulate external water and soil loads. The steel inner wall (4) is located inside the shield tunnel section (1), and a cavity is formed between the outer wall of the steel inner wall (4) and the inner wall of the shield tunnel section (1). The cover plate (5) is fixed to the steel inner wall (4) and pressed against the corresponding end face of the shield tunnel section (1) to seal the upper port of the cavity; The sealing support (6) supports the shield tunnel section (1) and seals the lower port of the cavity, making the cavity a closed cavity with both ends closed in the axial direction. Interface (7) is connected to the sealed cavity and is used to inject fluid into the sealed cavity to establish positive pressure inside the shield tunnel section, or to extract gas from the sealed cavity to establish negative pressure inside the shield tunnel section.

2. The test device for internal water pressure or low vacuum shield tunnel structural performance as described in claim 1, characterized in that: The sealing support is a concrete base. An annular groove is opened on the upper surface of the concrete base. An elastic sealing element (61) is laid in the annular groove. The shield tunnel section (1) and the steel inner support (4) are both placed on the elastic sealing element (61). After being compressed, the elastic sealing element (61) fills and seals the lower port of the cavity.

3. The test device for internal water pressure or low vacuum shield tunnel structural performance as described in claim 1, characterized in that: The hydraulic bladders (3) are evenly distributed along the circumference, and each hydraulic bladder (3) can be pressurized independently.

4. The test device for internal water pressure or low vacuum shield tunnel structural performance as described in claim 1, characterized in that: The outer steel support (2) and the inner steel support (4) are both circular ring components, and the shield tunnel section (1), the outer steel support (2) and the inner steel support (4) are arranged coaxially.

5. The test device for internal water pressure or low vacuum shield tunnel structural performance as described in claim 1, characterized in that: A support platform (41) is provided on the outside of the steel inner wall (4). A fixed column is provided on the support platform (41). The cover plate (5) is inserted into the fixed column and a nut is threaded onto the fixed column.

6. The test device for internal water pressure or low vacuum shield tunnel structural performance as described in claim 1, characterized in that: The cover plate (5) simultaneously presses against the end face of the shield tunnel section (1), and an elastic sealant is provided at the contact points between the cover plate (5), the shield tunnel section (1), and the steel inner rail (4).

7. The test device for internal water pressure or low vacuum shield tunnel structural performance as described in claim 1, characterized in that: The interface (7) is connected to a water pump for injecting water into the sealed cavity to establish positive pressure.

8. The test device for internal water pressure or low vacuum shield tunnel structural performance as described in claim 1, characterized in that: The interface (7) is connected to a vacuum pump to extract gas from the sealed cavity to establish a negative pressure.

9. The test device for internal water pressure or low vacuum shield tunnel structural performance as described in claim 8, characterized in that: After the vacuum pump is running, the absolute pressure inside the sealed cavity is maintained at 1×10⁻⁶. 2 Pa ~ 1×10 5 Low vacuum range of Pa.

10. A test method for a test device for the structural performance of a shield tunnel under internal water pressure or low vacuum as described in any one of claims 1-9, characterized in that: Includes the following steps: (a) Place the shield tunnel section (1) on the sealing support (6) so that the sealing support (6) seals the lower port of the shield tunnel section (1); (b) A steel outer support (2) is installed on the outside of the shield tunnel section (1), and a hydraulic bladder (3) is arranged between the steel outer support (2) and the shield tunnel section (1). (c) A steel inner wall (4) is provided on the inner side of the shield tunnel section (1) so that a cavity is formed between the outer wall of the steel inner wall (4) and the inner wall of the shield tunnel section (1); (d) Fix the cover plate (5) to the steel inner wall (4) and press it against the corresponding end face of the shield tunnel section (1) to seal the upper port of the cavity, thereby forming a closed cavity with both ends closed in the axial direction. (e) Activate the hydraulic bladder (3) to apply continuously distributed pressure to the outer wall of the shield tunnel segment (1), wherein the load applied by any one hydraulic bladder is calculated according to the following formula: ， in: P represents the vertical soil and water load, measured in MPa. P n1 and P n2 For the first The horizontal soil and water load corresponding to the two ends of each hydraulic bladder is expressed in MPa. θ n1 and θ n2 For the first The central angles between the two ends of each hydraulic bladder and the center line of the arch are expressed in degrees. (f) Inject fluid into the sealed cavity through the interface (7) to establish positive pressure inside the shield tunnel section (1), or extract gas from the sealed cavity to establish negative pressure inside the shield tunnel section (1); (g) By applying the load in step (e), the external water and soil load is simulated and works together with the internal pressure in step (f) to complete the coupled loading test.

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