Double-steel-plate concrete immersed tunnel structure of integrated variable-stiffness chamber

Abstract

The invention relates to the field of immersed tube tunnel engineering, in particular to a double-steel-plate concrete immersed tube tunnel structure of an integrated variable stiffness cavity. The structure comprises a multi-compartment double-steel-plate concrete pipe joint defined by an outer side steel plate (1), an inner side steel plate (2) and a plurality of compartment partition plates (3), part of compartments are filled with common concrete (4), and part of the compartments are constructed into variable-rigidity functional cavities. An energy dissipation and shock absorption chamber (5) is arranged close to the connecting part of the pipe joint connector and the shore; a flexible adaptive chamber (6) is arranged in the differential settlement sensitive area; rigidity adjusting chambers (7) are arranged in selected compartments. Compared with an existing bulkhead type double-steel-plate concrete immersed tunnel in which concrete is uniformly poured inside, the rigidity of the pipe joints is distributed as required along the line and can be adjusted and controlled, the internal force concentration of the joints and the transition sections is remarkably reduced, and the anti-seismic capacity and the deformation adapting capacity of the ultra-long immersed tunnel are improved.

Description

Technical Field

[0001] This invention relates to the fields of underwater transportation engineering, tunnel engineering, and structural engineering, specifically to a double-steel-plate concrete composite structure for immersed tunnels across rivers and seas, and more particularly to a double-steel-plate concrete immersed tunnel structure that integrates variable stiffness chambers and can achieve optimized stiffness distribution along the line and adjustable control during operation. It also relates to a stiffness control method based on this structure and its application in seismic resistance, differential settlement resistance, and temperature effect control. Background Technology

[0002] Double-steel-plate concrete composite structures, consisting of two layers of steel plates and an intermediate concrete filling layer, offer advantages such as excellent load-bearing capacity, rapid construction, and strong waterproofing and corrosion resistance. They have been applied in high-rise buildings, bridge towers, underground structures, and immersed tunnels. For underwater immersed tunnels, the compartmentalized double-steel-plate concrete immersed tunnel structure has been proposed and practically adopted in recent years. This structure creates multiple compartments by setting longitudinal and transverse partitions between the two steel plates, with the compartments integrally filled with concrete to improve bending, shear, and compressive strength, while also providing good waterproofing. Projects such as the Shenzhen-Zhongshan Bridge have extensively used compartmentalized double-steel-plate concrete immersed tunnel structures, and corresponding construction and design methods have been developed.

[0003] A common characteristic of existing compartmentalized double-steel-plate concrete immersed tunnels is that the interiors of the compartments are typically constructed using ordinary concrete of the same or similar strength grade, forming "rigid tube sections" with approximately uniform overall stiffness. Existing research mainly focuses on the flexural bearing capacity, shear performance, local stability, and casting defects of this type of structure, without differentiating the functions of the compartments. The internal filling materials are basically consistent in mechanical properties.

[0004] On the other hand, immersed tunnels face complex and variable environmental and load conditions during service, including: (1) long-term consolidation of the foundation, changes in backfilling and uneven compression causing differential settlement, which generates additional internal forces at the pipe sections and pipe joints; (2) seasonal changes in water temperature and air temperature cause pipe sections to generate non-uniform temperature fields, resulting in constrained temperature deformation and additional stress; (3) accidental effects such as earthquakes and ship collisions place high requirements on the overall tunnel and joint areas for seismic isolation and energy dissipation.

[0005] To address the above issues, existing projects typically employ the following approaches:

[0006] Flexible or semi-rigid structures are installed at the joints: such as shear key supports and rubber supports are used to form a certain degree of flexibility and energy dissipation capacity at the pipe joints, so as to improve the mechanical properties and seismic performance of the joints.

[0007] Optimize the ratio of joint stiffness to pipe section stiffness: Through structural analysis and experimental research, adjust the joint structure and materials, and control the stiffness ratio of the joint to the pipe section body to reduce internal force concentration;

[0008] In the overall design, appropriately reducing local reinforcement or changing the cross-section can guide plastic development or adapt to uneven deformation to a certain extent.

[0009] However, the aforementioned traditional measures still have the following limitations:

[0010] Stiffness control is concentrated at the joint structure level: existing technologies mainly introduce flexibility and energy dissipation elements into the rubber waterstop, shear key and local steel components of the pipe joint. The immersed pipe section body is still cast with internal homogeneous concrete. It is difficult to finely control the stiffness distribution along the longitudinal direction and cross-section of the tunnel, and the internal force redistribution capacity near the joint is limited.

[0011] Lack of functionalization and zoning design of interior materials: Although the compartmentalized double steel plate concrete structure provides a natural multi-compartment space, the published literature still treats each compartment as a unified concrete pouring space, and does not utilize different mechanical properties materials to fill different compartments to achieve the concept of "stiffness customization and spatial distribution as needed".

[0012] The structural performance during operation is either not adjustable or difficult to adjust: Most existing flexible joints and shear keys are determined once during the design phase. Even if leakage is repaired or overall stiffness is enhanced through grouting or other means during service, these methods are mostly applied to the outside of the pipe section or in narrow spaces at the joint, making them highly passive and with limited adjustable range. No systematic technology has yet been publicly disclosed for actively, reversibly, or in stages enhancing the internal stiffness of the immersed tunnel section.

[0013] Insufficient coordinated control of differential settlement and earthquakes: Currently, differential settlement adaptation and earthquake damping are often considered separately, for example, by reinforcing the foundation, using flexible joints, and setting high-damping supports. However, there is a lack of an integrated structure that simultaneously takes into account "flexible settlement adaptation" and "local earthquake resistance" in the same structural system. This means that the overall safety margin of ultra-long immersed tunnels under complex working conditions still has room for improvement.

[0014] In summary, existing compartmentalized double-steel-plate concrete immersed tunnel structures have not fully utilized the multi-compartment space for functional design, have not achieved active control of stiffness distribution along the route or adjustable reinforcement during operation, and are unable to fundamentally alleviate the problem of internal force concentration at joints and onshore connection zones, nor can they simultaneously meet the comprehensive needs of long-term settlement adaptation and seismic energy dissipation. Therefore, it is necessary to propose a novel double-steel-plate concrete immersed tunnel structure that integrates variable stiffness and energy dissipation functions at the compartment level, transforming it from a traditional "passive load-bearing component" into an "actively adaptive structure" with designable, multi-mode mechanical response, thereby improving the overall safety and disaster resistance of ultra-long immersed tunnels. Summary of the Invention

[0015] The purpose of this invention is to address the problems of uniform concrete filling, difficulty in controlling stiffness distribution, and difficulty in adjusting structural performance during operation in existing compartmented double-steel-plate concrete immersed tunnels. It proposes a double-steel-plate concrete immersed tunnel structure with integrated variable stiffness chambers and a method for stiffness control. Through functional and differentiated design of the filling materials and structures within the chambers, the following are achieved: stiffness is distributed as needed along the tunnel's longitudinal and cross-sectional directions; stiffness is appropriately reduced and energy dissipation is enhanced in joints and onshore connection areas; flexibility is improved in areas sensitive to differential settlement of the foundation; and stiffness can be enhanced through later-stage grouting in other important sections. The overall coordinated operation of the tunnel section body and joint structure reduces abrupt stiffness changes and internal force concentrations between traditional rigid tunnel sections and flexible joints. By reserving adjustable chambers and integrating monitoring and grouting design, dynamic adjustment and phased improvement of tunnel section stiffness during operation can be achieved, extending the tunnel's service life and improving its seismic resistance and deformation adaptability.

[0016] To achieve the above objectives, the present invention proposes the following technical solution.

[0017] (A) Based on the traditional compartmentalized double-steel-plate concrete pipe section, multiple compartments are formed by outer steel plates (1), inner steel plates (2), and compartment partitions (3), and each compartment was originally filled with ordinary concrete (4). This invention divides some of the compartments into different types of variable stiffness functional chambers:

[0018] Energy dissipation and vibration reduction chamber (5): It is located near the pipe joint (13) and the transition section of the onshore connection structure (14). Instead of ordinary concrete, it is filled with high-damping rubber, viscoelastic material or metal energy dissipation element (8), so that the area will generate controlled shear or bending deformation under the action of earthquake and wave, and achieve energy dissipation through material viscous damping or metal yielding.

[0019] Flexible adaptation chamber (6): Located in the section of the pipe with weak foundation and sensitive to differential settlement, the interior is filled with lightweight concrete or foamed concrete with low elastic modulus (9). By reducing local stiffness, it allows for greater controllable deformation, thereby reducing the constraint stress and cracking risk caused by uneven settlement and temperature effects.

[0020] Stiffness adjustment chamber (7): A reserved cavity (10) is set in a selected compartment and connected to the outside of the pipe section through a grouting pipe (11). In the early stage of operation, the cavity can be left empty or filled with easily removable materials. As structural monitoring data accumulates, high-strength grout can be injected into the cavity at the required time and location to improve local stiffness and realize phased optimization and dynamic reinforcement of structural performance.

[0021] (B) Based on the above-mentioned chamber layout, combined with foundation conditions, temperature field analysis and seismic response analysis, the layout of various variable stiffness functional chambers along the longitudinal direction and cross section of the tunnel is optimized to form a stiffness zoning layout scheme, so that the stiffness of the pipe section body and the joint structure (such as GINA waterstop, shear key, etc.) are coordinated and matched as a whole.

[0022] (C) Install structural health monitoring sensors (12) inside and outside the pipe section, including strain gauges, accelerometers, displacement or settlement monitoring devices, etc., and identify areas with concentrated internal forces or excessive deformation through long-term monitoring data. Then, match these areas with the position of the stiffness adjustment chamber (7) to achieve closed-loop control of stiffness regulation.

[0023] Compared with the prior art, the present invention has at least the following beneficial effects:

[0024] Functionalized compartments enable customized stiffness: Traditional compartmentalized double-plate concrete immersed tunnels typically fill all compartments with concrete of uniform strength and stiffness, failing to utilize the compartment space for functional zoning. This invention, for the first time, proposes a comprehensive configuration at the compartment level: "energy-dissipating and vibration-damping chambers + flexible adaptive chambers + stiffness-adjusting chambers." This transforms the tunnel structure from a passive component with uniform stiffness into an active adaptive system with multiple response modes and programmable stiffness distribution.

[0025] Eliminating abrupt changes in stiffness between the joint and the pipe section body, and reducing internal force concentration: By arranging energy-dissipating and vibration-damping chambers in the joint and onshore connection areas, a "soft band" is formed inside the pipe section, which moderately reduces the stiffness of the body near the joint and provides energy dissipation capacity. This smooths the stiffness transition between the flexible joint and the rigid section of the pipe section away from the joint, reduces bending moment and shear force concentration, reduces the peak stress on the joint rubber support and shear key, and improves the joint's seismic resistance and durability.

[0026] Enhancing adaptability to differential settlement and temperature effects: The flexible adaptation chamber is filled with low-modulus lightweight concrete or foamed concrete, providing additional controllable deformation capacity without significantly reducing the overall bearing capacity. In this way, when uneven settlement occurs in the foundation or additional deformation is caused by temperature gradients, some deformation demand can be released through the flexible chamber, reducing the constraint stress and cracking risk in areas with higher stiffness, and avoiding the formation of "rigid abrupt change points" in the longitudinal direction of the tunnel.

[0027] Adjustable stiffness during operation enables dynamic optimization of structural performance: The stiffness adjustment chamber is achieved through pre-reserved cavities and grouting pipes. Combined with long-term monitoring data, weak sections exposed during operation can be reinforced through phased grouting, thereby dynamically changing the local stiffness and internal force distribution. This post-operational adjustable design breaks through the rigid "one-time design, lifelong use" model of traditional immersed tunnel structures, providing a means for continuously optimizing the structural performance of cross-sea immersed tunnels with ultra-long service lives throughout their entire life cycle.

[0028] Compatible with existing construction technologies and industrially applicable: The variable stiffness chamber of this invention relies on the existing compartmentalized double steel plate concrete pipe section structure. It is mainly achieved by adjusting the chamber filling material and adding reserved cavities and grouting pipes. It has little impact on the steel shell and the overall manufacturing process. It is compatible with the factory prefabrication-floating-sinking construction system used in existing projects such as the Shenzhen-Zhongshan Bridge. It has good engineering feasibility and economy. Attached Figure Description

[0029] To more clearly illustrate the technical solution of the present invention, the present invention will be further described below in conjunction with the accompanying drawings and specific embodiments. The accompanying drawings are used to illustrate one or more embodiments of the present invention and do not constitute a limitation on the scope of protection of the present invention.

[0030] Figure 1 This is a schematic cross-sectional view of the double-steel plate concrete immersed tunnel with integrated variable stiffness chamber according to the present invention.

[0031] Figure 2 A schematic diagram of the energy dissipation and vibration damping chamber layout in the pipe joint area (along the longitudinal section of the tunnel).

[0032] Figure 3 A schematic diagram of the flexible adaptation chamber layout in the differential settlement sensitive area (along the longitudinal section of the tunnel).

[0033] Figure 4 This is a schematic diagram of the stiffness adjustment chamber and grouting system.

[0034] Figure 5 This is a schematic diagram of a monitoring-stiffness control system based on the structure of this invention.

[0035] For ease of understanding, the components or parameters represented by the labels in the attached drawings are as follows: 1—Outer steel plate; 2—Inner steel plate; 3—Compartment bulkhead; 4—Ordinary concrete infill; 5—Energy dissipation and vibration damping chamber; 6—Flexible adaptation chamber; 7—Stiffness adjustment chamber; 8—Metallic energy dissipation element / damper; 9—Low modulus lightweight concrete / foamed concrete; 10—Reserved cavity; 11—Grouting pipe; 12—Structural health monitoring sensor; 13—Pipe joint; 14—Onshore connection structure; 15—High damping rubber / viscoelastic material layer; 16—Grouting port and grouting stop device; 17—Monitoring data acquisition and control unit; 18—Schematic diagram of foundation and backfill soil. Detailed Implementation

[0036] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings. Those skilled in the art will understand that various equivalent substitutions or modifications can be made to the following embodiments without departing from the spirit and scope of the present invention.

[0037] Example 1: Basic Structure and Cabin Classification Layout

[0038] like Figure 1 As shown, a double-steel-plate concrete immersed tunnel structure with integrated variable stiffness chambers adopts a rectangular or near-rectangular tube section cross-section. Each tube section is formed by an outer steel plate 1 and an inner steel plate 2, creating a box-shaped cross-section. Within this cross-section, several compartment partitions 3 are arranged vertically and horizontally, dividing the hollow space into multiple compartments. Most of the compartments are filled with ordinary concrete 4 to meet the basic performance requirements of tunnel compression resistance, bending resistance, shear resistance, and waterproofing.

[0039] Based on this, this embodiment functionalizes some of the compartments and classifies them into the following categories:

[0040] Energy-dissipating and vibration-damping chamber 5

[0041] Location of arrangement: With the pipe joint 13 as the center, energy dissipation and vibration damping chambers 5 are set in several compartments on both sides of the joint along the longitudinal direction of the tunnel; in the transition pipe section connected to the onshore connection structure 14, energy dissipation and vibration damping chambers are also set in the compartments near the connection interface.

[0042] Section arrangement: It is preferable to arrange the section near the side walls and top or bottom slab areas to make it more sensitive to bending and shear deformation. For example, a row of energy-dissipating and damping chambers can be arranged above and below the side walls to generate greater shear deformation under horizontal seismic loading.

[0043] Filling material: Instead of pouring ordinary concrete 4, the energy-dissipating and vibration-damping cavity is filled with high-damping rubber or viscoelastic material 15. Metal energy-dissipating elements 8, such as shear yield steel plates, buckling restraint support units or friction dampers, can also be embedded in this material.

[0044] Flexible Adaptive Chamber 6

[0045] Location: Based on the results of foundation investigation and settlement prediction, within the range of pipe sections with large estimated differential settlement (e.g., weak foundation sections, intermediate settlement trough areas), select several longitudinally continuous or discontinuous compartments as flexible adaptation chambers 6.

[0046] Filling material: The flexible adaptable cavity is filled with low-elasticity lightweight concrete or foamed concrete 9, the elasticity modulus of which is approximately 4 times that of ordinary concrete. It has a higher density than other materials, thus providing additional deformation capacity without significantly weakening the overall load-bearing capacity.

[0047] Cross-sectional arrangement: It is preferred to arrange the flexible compartments in the tension zone of the cross-section, such as near the tension edges of the top and bottom plates, so that they can play a flexible release role under the flexural deformation caused by temperature gradient or differential settlement.

[0048] Stiffness adjustment chamber 7

[0049] Location of arrangement: Along the longitudinal direction of the tunnel, select several compartments in several key pipe sections as stiffness adjustment chambers 7. These compartments can be located near the joints or in the mid-span area, or they can be distributed within the sections with large differential settlement prediction values.

[0050] Structural features: such as Figure 4 As shown, the stiffness adjustment chamber 7 retains a certain volume of reserved cavity 10 during the prefabrication stage, which can be formed by a detachable template or a crushable lightweight filling material. The grouting pipe 11 penetrates from the top plate of the pipe section and communicates with the reserved cavity 10. A grouting port and a grout-stopping device 16 are provided on the outer surface of the pipe section. In the early stages of operation, the reserved cavity can be left empty or filled with only a small amount of low-strength material to maintain low stiffness. When it is necessary to enhance the stiffness of this area, high-strength cement-based or polymer-based grout can be injected through the grouting pipe 11. After hardening, this significantly improves the local stiffness and load-bearing capacity of the chamber. The ordinary compartment continues to be integrally cast using ordinary concrete 4, forming a comprehensive structural system with both load-bearing capacity and stiffness adjustment function together with the aforementioned functional chambers.

[0051] Example 2: Energy dissipation and vibration reduction design in the pipe joint area

[0052] like Figure 2 The figure shows a longitudinal cross-section of the pipe joint 13 area. Adjacent pipe sections are connected by a conventional joint structure, including an outer steel shell contact surface, GINA rubber waterstop, shear key, and rubber support (not shown in detail in the figure), which is similar to the structure of existing immersed tunnels. The difference is that the present invention sets energy-dissipating and vibration-damping chambers 5 within a certain length range of pipe sections on both sides of the joint 13.

[0053] Longitudinal distribution

[0054] Taking the longitudinal position of joint 13 as the origin, select 1-2 pipe sections on each side as the "joint influence zone". Energy-dissipating and vibration-damping chambers 5 are arranged inside these pipe sections near the joint section, appropriately reducing the stiffness of the pipe section near the joint and providing energy dissipation functionality. The energy-dissipating and vibration-damping chambers can be arranged in a stepped manner along the longitudinal direction, meaning the closer to the joint, the more numerous and larger the energy-dissipating chambers; the further away from the joint, the fewer the chambers, allowing a smooth transition in stiffness to that of ordinary pipe sections.

[0055] Cross-sectional layout and material structure

[0056] One or more rows of energy-dissipating and damping chambers 5 are arranged at the top and bottom of the side walls to withstand shear deformation under horizontal seismic action and longitudinal temperature deformation. Energy-dissipating and damping chambers are arranged near the arch foot / corner of the top and bottom plates to generate energy-dissipating bending zones under vertical seismic action and uneven settlement. The interior of the chambers is preferably filled with high-damping rubber or viscoelastic material 15, which is connected to the steel plates 1 and 2 and the compartment bulkhead 3 by adhesives or mechanical anchor plates to form shear-bearing units; metal energy-dissipating elements 8 such as shear yield steel plates or friction plates can be embedded in the rubber or viscoelastic material to further improve the energy dissipation capacity.

[0057] Working mechanism

[0058] Under the dynamic action caused by earthquakes, waves or vehicle loads, the relative rotation angle and shear deformation of the joint area will be partially concentrated in the energy dissipation and damping chamber 5. The high damping material and metal damper in the chamber dissipate energy through repeated shear deformation and yielding, reducing the peak stress transmitted to the ordinary concrete 4 and the joint shear key and waterstop, thereby improving the overall seismic resistance and durability of the joint.

[0059] Example 3: Flexible Adaptive Design for Differential Settlement Sensitive Zones

[0060] like Figure 3 The diagram shows a longitudinal profile of a differential settlement sensitive section. Based on foundation investigation and long-term settlement prediction, a subsidence trough is expected to form in a certain mid-span area. To avoid a significant increase in bending moment in this area due to uneven foundation stiffness, changes in siltation, or changes in groundwater level, this embodiment arranges a flexible adaptive chamber 6 in this area.

[0061] Longitudinal and cross-sectional layout

[0062] Among several pipe sections within the expected settlement trough area, the compartments closest to the tension edges of the top and / or bottom plates are selected as flexible adaptation chambers 6, arranged continuously along the longitudinal direction or at certain intervals to form flexible zones. A symmetrical arrangement can be adopted in the cross-section to maintain the basic symmetry of the overall structural stiffness and avoid additional torsion.

[0063] Material selection

[0064] Using dry density t / m 3 The compressive strength of the lightweight concrete or foamed concrete 9 between these can be selected as: Grade, with an elastic modulus less than 4 of ordinary concrete The material can be pumped into the flexible adaptation chamber 6, and after hardening, it forms a reliable bond with the compartment bulkhead 3 and steel plates 1 and 2 to withstand the necessary compressive and shear stresses.

[0065] The working mechanism involves the relatively concentrated deformation at the location of the flexible adaptation chamber 6 when uneven settlement occurs in the foundation. Its low stiffness allows for a larger controllable deflection, thereby reducing the tensile stress and peak bending moment in the ordinary concrete 4 area and lowering the risk of crack formation. At the same time, due to the low density of lightweight concrete or foamed concrete 9, the self-weight of the structure can be reduced to a certain extent, thus reducing the additional effect on the foundation.

[0066] Example 4: Stiffness Adjustment Chamber and Grouting System

[0067] like Figure 4 As shown in the figure, this embodiment further explains the structure and construction method of the stiffness adjustment chamber 7.

[0068] Pre-reserved cavity molding

[0069] During the prefabrication of pipe sections in the factory, a removable inner mold or easily broken material (such as foam plastic blocks, low-strength inorganic foam materials, etc.) is installed in the selected compartment. After the external steel shell and compartment bulkhead 3 are welded together, ordinary concrete 4 is poured around the cavity to surround the inner mold or easily broken material. After the ordinary concrete 4 reaches a certain strength, if a removable inner mold is used, it is pulled out through pre-reserved holes to form a pre-reserved cavity 10; if an easily broken material is used, it is broken by puncture or drilling before grouting during operation, so that it no longer provides significant rigidity.

[0070] Grouting pipe layout

[0071] The grouting pipe 11 is made of steel or high-strength plastic and enters from the top plate or side wall of the pipe section. A grouting port and a grout-stopping device 16 are installed at the pipe opening. A check valve can be installed inside the pipe to prevent backflow. The grouting pipe 11 can be arranged in a multi-branch form inside the cavity to ensure that the grout can fill the entire reserved cavity 10.

[0072] Stiffness adjustment during operation

[0073] During tunnel operation, structural health monitoring sensors 12 collect data on the rotation angle, deformation, strain, and settlement of pipe joints 13, which are then analyzed by the monitoring data acquisition and control unit 17. If the deformation or strain of a certain section approaches the design limit or safety threshold, the control unit recommends grouting in the corresponding stiffness adjustment chamber 7. The grouting material can be selected according to design requirements, such as high-strength cement-based grout, micro-expansion grout, or polymer-modified grout. After the grout hardens, the reserved cavity 10 forms a new high-stiffness concrete or composite material block, significantly improving the local stiffness and load-bearing capacity at that location, thereby redistributing internal forces and reducing the stress level of critical components.

[0074] Repeated and phased implementation

[0075] The stiffness adjustment in this embodiment can be implemented in batches according to different stages of the operation period. For example, in the early stage of structural service, a lower stiffness can be maintained to adapt to initial settlement and temperature deformation. In the middle and later stages, the overall stiffness can be gradually increased by grouting to meet the durability and later load requirements. Different stiffness adjustment chambers 7 can be grouted separately or in combination to achieve flexible control in space and time.

[0076] Example 5: Integrated Monitoring-Stiffness Control System

[0077] like Figure 5 As shown in the figure, this embodiment demonstrates a monitoring-stiffness control system based on the structure of the present invention.

[0078] Monitoring deployment

[0079] Multiple strain gauges, accelerometers, and displacement gauges were installed near joint 13 to monitor joint opening and closing, shear slip, and seismic response. Settlement observation points were set up along the tunnel longitudinally in the differential settlement sensitive section to obtain settlement curves at different times. Strain gauges and thermometers were installed near the critical stiffness adjustment chamber 7 to accurately assess the stress and environmental conditions around the chamber.

[0080] Data processing and discrimination

[0081] The monitoring data acquisition and control unit 17 performs statistical analysis on the data collected in real time or periodically, compares it with the response envelope curve predicted in the design phase, and identifies areas that exceed or are close to exceeding limits. Based on the structural analysis model, the monitoring results are fed back into the numerical model to update the foundation stiffness, temperature field, and structural stiffness parameters, forming a "digital twin" model to provide a basis for stiffness control decisions.

[0082] Stiffness control strategy

[0083] When the angular or shear deformation of a joint area exceeds the warning value, grouting can be performed in the stiffness adjustment chambers 7 on both sides of the joint to enhance the stiffness of the pipe section near the joint, thereby reducing the stress on the joint rubber support and shear key. When the deflection or tensile strain of a settlement trough section approaches the limit, grouting can be performed in the stiffness adjustment chambers at both ends of the settlement trough to form a "support zone" and limit the further development of the settlement trough. After an extreme earthquake, based on the damage detection results, grouting reinforcement can be carried out in the stiffness adjustment chambers near the damaged area, or the energy-dissipating elements 8 can be replaced in the energy-dissipating and damping chambers 5 to restore and enhance the safety reserve of the structure.

[0084] As can be seen from the above embodiments, the present invention does not simply transplant existing vibration damping bearings or flexible joint technologies into immersed tunnels. Instead, it utilizes the multi-compartment characteristics of the compartmentalized double steel plate concrete structure to systematically integrate multiple functions of "flexibility, rigidity, energy dissipation, and adjustability" at the compartment level. This achieves an essential transformation of the stiffness distribution of immersed tunnels from "uniform and passive" to "zoned and adjustable, customized as needed," which is conducive to improving the overall safety and service reliability of ultra-long immersed tunnels across the sea and rivers under differential settlement of the foundation, temperature effects, and earthquake disasters.

Claims

1. A double-steel-plate concrete immersed tunnel structure with integrated variable stiffness chambers, comprising: A number of immersed tunnel sections are arranged longitudinally along the tunnel. Each section is formed by an outer steel plate (1), an inner steel plate (2), and several compartment partitions (3) arranged laterally and / or vertically to form a multi-compartment double-steel-plate cavity structure. At least part of the compartment is filled with ordinary concrete (4). The characteristic is that at least a portion of the compartment is constructed as a variable stiffness functional chamber. The variable stiffness functional chamber includes an energy-dissipating and vibration-damping chamber (5) located near the tunnel section joint (13) and / or the onshore connection structure (14), which is filled with high damping. Rubber, viscoelastic materials and / or metal damping elements (8); flexible adaptation chambers (6) set in sections where significant differential settlement is expected, filled with low elastic modulus lightweight concrete and / or foamed concrete (9); stiffness adjustment chambers (7) set in which stiffness needs to be adjusted during operation, with a reserved cavity (10) and a grouting pipe (11) connected thereto, for later injection of high-strength grout to improve local stiffness; thereby enabling the immersed tunnel to have differentiated and adjustable overall stiffness and deformation capacity at different locations along the line.

2. The immersed tunnel structure according to claim 1, characterized in that: The energy-dissipating and vibration-damping chambers (5) are arranged in pairs or groups on both sides of the joint section along the height direction of the pipe section. The high-damping rubber or viscoelastic material is bonded or mechanically connected with the cabin partition (3) and steel plate to form a continuous shear energy-dissipating layer, so that the joint area will produce controlled shear deformation under horizontal and vertical seismic action.

3. The immersed tunnel structure according to claim 1 or 2, characterized in that: The metal damping element (8) is a yielding steel damper, a friction damper, or a shear yielding connector. One end of the damper is connected to the outer steel plate (1), and the other end is connected to the inner steel plate (2) and / or the compartment bulkhead (3). It dissipates seismic input energy through repeated yielding or friction slip.

4. The immersed tunnel structure according to claim 1, characterized in that: The flexible adaptive chamber (6) uses a dry density of no more than Elastic modulus less than Lightweight concrete or foamed concrete, in which The elastic modulus of ordinary concrete (4) for pipe sections is used to control the deformation requirements of the cavity area under uneven settlement and temperature gradient.

5. The immersed tunnel structure according to claim 1, characterized in that: The flexible adaptive chamber (6) is arranged in a continuous or discontinuous strip along the longitudinal direction of the tunnel, and its length covers the range of differential settlement influence. It is preferentially arranged in the tension zone along the cross-sectional height direction to reduce the risk of concrete cracking.

6. The immersed tunnel structure according to claim 1, characterized in that: The reserved cavity (10) of the stiffness adjustment chamber (7) is formed by a detachable template or easily broken filling material during the prefabrication stage. The grouting pipe (11) is arranged through the top plate and / or side wall of the pipe section, and a grouting port and a grouting stop device are set at the end to facilitate the implementation of zoning and phased post-grouting during the operation period.

7. The immersed tunnel structure according to claim 1, characterized in that: The stiffness adjustment chamber (7) corresponds to the structural health monitoring sensor (12) arranged inside and outside the pipe section. The sensor is used to monitor the pipe section joint rotation angle, shear deformation, strain and / or settlement. Based on the monitoring results, the location of the stiffness adjustment chamber to be grouted and the amount of grouting are determined, so as to realize the feedback control of the pipe section stiffness.

8. The immersed tunnel structure according to claim 1, characterized in that: The variable stiffness functional chambers are arranged symmetrically or approximately symmetrically in the vertical and / or horizontal directions within the cross-sectional area, so that the overall force transmission path of the structure remains balanced and the overall stability is not reduced due to the weakening of local stiffness.

9. The immersed tunnel structure according to any one of claims 1 to 8, characterized in that: The specific type and layout range of the variable stiffness functional chambers are determined based on the longitudinal foundation stiffness distribution, temperature field analysis results, and seismic response analysis results of the immersed tunnel, forming a stiffness zoning layout scheme along the line to ensure that the stiffness of the pipe section body and the mechanical properties of the joints are matched in a coordinated manner.

10. A method for stiffness control of an immersed tunnel structure according to any one of claims 1 to 9, characterized in that, include: (1) During the operation of the immersed tunnel, strain, rotation and settlement data near the pipe joint (13) and the onshore connection structure (14) are obtained by the structural health monitoring sensor (12); (2) Based on the comparison of the monitoring data with the design threshold, the abnormal internal force or deformation section is identified; (3) The stiffness adjustment chamber (7) corresponding to the abnormal section is selected, and high-strength grout is injected into the reserved cavity (10) through the grouting pipe (11) to improve the local stiffness after the grout hardens; (4) If necessary, the filling material of the energy dissipation and vibration reduction chamber (5) or the flexible adaptation chamber (6) is replaced or reinforced to re-optimize the overall stiffness distribution and energy dissipation capacity of the tunnel.

Images