Reef limestone underground chamber shock absorption system

Abstract

The application discloses a reef limestone underground chamber damping system and belongs to the field of damping devices. The reef limestone underground chamber damping system comprises an elastic bearing assembly, micro-grouting hole pipelines, composite variable resistors and pressure sensors. The elastic bearing assembly comprises basalt micro-tendon and stainless steel energy dissipation nodes. A plurality of basalt micro-tendons form a constraint network along the circumference and axis of the chamber on the inner wall of the chamber. The stainless steel energy dissipation nodes are arranged at the intersection connection between the basalt micro-tendons. A plurality of micro-grouting hole pipelines are arranged in the constraint network along the axis of the chamber. The pressure sensors are embedded in the rock above the chamber. A plurality of composite variable resistors are arranged at the arch foot of the chamber. The three-stage collaborative mechanism of "basalt micro-tendon constraint-SMA-MRF collaborative energy dissipation-SMA heating phase change recovery and micro-grouting" solves the adaptability bottleneck of traditional anti-seismic technology in reef limestone underground space, and improves the anti-seismic performance and long-term service reliability.

Description

Technical Field

[0001] This invention relates to the field of vibration reduction systems, and more specifically, to a vibration reduction system for underground caverns in reef limestone. Background Technology

[0002] Earthquake protection for underground tunnels on coral islands and reefs is a unique challenge in marine engineering. The brittle nature of reef limestone strata, coupled with the highly corrosive environment of the islands and reefs, presents a bottleneck in the adaptability of traditional earthquake-resistant technologies. As the main load-bearing medium of the islands and reefs, reef limestone has a dynamic damping ratio of only 2-5%, making it prone to brittle cracking under seismic loads, with strength decreasing by more than 50% after peak load. Meanwhile, the high salt spray environment can cause the annual corrosion rate of metal damping components to exceed 0.3 mm, seriously affecting long-term service performance.

[0003] Existing seismic resistance technologies for underground engineering are mainly divided into two categories: passive energy dissipation and active control. Passive energy dissipation technologies (such as lead-core rubber bearings and friction dampers) suffer from problems such as large residual deformation after earthquakes and insufficient durability in corrosive environments. Active control technologies (such as magnetorheological dampers and piezoelectric actuators) can be adjusted in real time, but they rely on complex sensing systems, which limits their reliability in scenarios with unstable power supply on islands and reefs. Neither type of technology fully considers the geological characteristics of reef limestone, which is characterized by "easy softening, low damping, and strong dispersion," resulting in a 30-40% reduction in vibration reduction efficiency compared to the design value in actual engineering projects. Summary of the Invention

[0004] To overcome the shortcomings of existing technologies, this invention provides a seismic damping system for underground caverns in reef limestone, which combines environmental adaptability, multi-stage energy consumption, and autonomous recovery, enabling targeted control of adverse geological characteristics of reef limestone and providing an efficient, durable, and intelligent seismic solution for underground engineering in islands and reefs.

[0005] To achieve this objective, the present invention adopts the following technical solution:

[0006] This invention provides a vibration reduction system for underground reef limestone chambers, including an elastic bearing component, micro-grouting hole pipes, a composite rheostat, and a pressure sensor. The elastic bearing component includes basalt micro-tendons and stainless steel energy-dissipating nodes. Multiple basalt micro-tendons form a constraint network along the circumference and axial direction of the chamber on the inner wall of the chamber. The stainless steel energy-dissipating nodes are located at the intersections between the basalt micro-tendons. Multiple micro-grouting hole pipes are arranged along the axial direction of the chamber within the constraint network. The pressure sensor is embedded in the rock above the chamber. Multiple composite rheostats are located at the arch foot of the chamber.

[0007] In a preferred embodiment of the present invention, the inner side of the constraint network is provided with a concrete lining.

[0008] In a preferred embodiment of the present invention, the stainless steel energy-consuming node includes a node body and an energy-consuming node connection end, and a plurality of the energy-consuming node connection ends are disposed on the outside of the node body.

[0009] In a preferred embodiment of the present invention, the composite rheostat includes an upper connecting steel plate, a lower connecting steel plate, an upper rubber pad, a lower rubber pad, a central flexible support column, a shape memory alloy rod, and a magnetorheological fluid variable cavity; the upper rubber pad is connected to the bottom of the upper connecting steel plate, the lower rubber pad is connected to the top of the lower connecting steel plate, and the central flexible support column, the shape memory alloy rod, and the magnetorheological fluid variable cavity are disposed between the upper rubber pad and the lower rubber pad.

[0010] In a preferred embodiment of the present invention, the two ends of the central flexible support column are respectively connected to the center of the upper rubber pad and the center of the lower rubber pad; a plurality of magnetorheological fluid variable cavities are arranged around the majority of the central flexible support columns, and a plurality of shape memory alloy rods are arranged around the magnetorheological fluid variable cavities.

[0011] In a preferred embodiment of the present invention, an excitation coil is provided outside the magnetofluid variable cavity, and the two ends of the magnetofluid variable cavity are respectively connected to the upper rubber pad and the lower rubber pad through flexible deformation support plates.

[0012] In a preferred embodiment of the present invention, the magnetorheological fluid variable excitation cavity is divided into a magnetorheological fluid variable cavity by a fluid cavity partition plate, and a plurality of magnetorheological fluid magnetically controlled auxiliary flow stagnant baffles are provided in the magnetorheological fluid variable cavity.

[0013] In a preferred embodiment of the present invention, the two ends of the shape memory alloy rod are respectively connected to the upper rubber pad and the lower rubber pad via threaded connectors; the shape memory alloy rod includes a stainless steel sleeve, a shape memory alloy wire bundle, and a micro displacement gauge; the shape memory alloy wire bundle and the micro displacement gauge are both disposed inside the stainless steel sleeve;

[0014] In a preferred embodiment of the present invention, an aerogel insulation layer is provided on the inner side of the stainless steel sleeve, and a PI heating film is applied to the outer side of the aerogel insulation layer.

[0015] In a preferred embodiment of the present invention, both the upper connecting steel plate and the lower connecting steel plate are provided with multiple mounting holes, and the flexible deformable support plate is provided with multiple connecting holes.

[0016] The beneficial effects of this invention are as follows:

[0017] This invention provides a seismic damping system for underground reef limestone chambers, applied to seismic protection of underground chambers in reef limestone layers on coral islands. It is well-suited to the unique geological characteristics of reef limestone, namely "high porosity, low strength, easy dissolution, and low damping," and the harsh environment of islands and reefs with high salt spray and temperature fluctuations. Through a three-stage synergistic mechanism of "basalt micro-tendon constraint - SMA-MRF synergistic energy dissipation - SMA heating phase change recovery and micro-grouting," it specifically addresses the adaptability bottleneck of traditional seismic technology in underground reef limestone spaces, achieving a dual breakthrough in seismic performance and long-term service reliability.

[0018] The innovative application of basalt micro-tendon technology in reef limestone underground chamber structures can precisely improve the defects of reef limestone, such as high brittleness, well-developed structural surfaces (dissolution fractures, bio-drilling holes), and easy deformation concentration, thus constructing a composite load-bearing system of "rigid surrounding rock - flexible constraint". The circumferentially arranged multi-layered basalt micro-tendons, fully bonded and anchored with epoxy resin, work synergistically with the reef limestone, transforming the uniaxial compression state of the reef limestone into triaxial compression, increasing its compressive strength by 40%–60%. Simultaneously, the tendon surface undergoes dual corrosion-resistant treatment with silane coupling agent and polyimide coating, adapting to the high humidity and high salinity environment of islands and reefs, effectively avoiding the problems of easy corrosion and short lifespan of metal components. Furthermore, through gradient stiffness matching design (the elastic modulus of the tendons is between that of reef limestone and steel components) and local densification treatment in the dissolution zone, stress concentration at the "rigid-flexible" interface can be avoided, reducing the stiffness dispersion of the reef limestone, inhibiting the initiation and propagation of microcracks in the early stages of loading, and providing a stable initial load-bearing guarantee for the underground chamber.

[0019] An innovative composite damping device combining SMA fiber and magnetorheological fluid (MRF) was constructed to create a deep protection system of "reef limestone - elastic constraint - intelligent energy dissipation." This composite device, serving as the core damping barrier, mitigates the risks of softening and shear instability in reef limestone under strong earthquakes through a dual mechanism of "elastic compensation - dynamic control": Ti-Ni-Cu SMA fibers utilize hyperelastic deformation to provide stable hysteretic energy dissipation, compensating for more than half of the strength decay after the reef limestone enters the plastic stage, thus providing continuous residual load-bearing capacity for the structure; the MRF damping cavity adjusts the damping force in real time, maintaining a fixed equivalent damping ratio.

[0020] During the post-earthquake recovery phase, the innovative application of SMA heating phase change recovery and micro-grouting synergistic technology can effectively repair residual deformation and functional degradation in reef limestone underground chambers, addressing the pain points of difficult post-earthquake repair and slow functional recovery in traditional earthquake-resistant structures. Through a zoned heating strategy, SMA wires can generate 2%–3% phase change recovery strain.

[0021] This multi-stage, multi-technology integrated design scheme significantly enhances the seismic safety and strategic support capabilities of underground chambers on islands and reefs, enabling them to maintain structural stability even under strong earthquakes and achieve rapid post-earthquake recovery and use. It provides reliable technical support for the long-term safe operation of strategic facilities such as underground storage depots and command and control facilities on islands and reefs in the South China Sea. Attached Figure Description

[0022] Figure 1 This is a structural schematic diagram of a reef limestone underground cavern vibration reduction system provided in a specific embodiment of the present invention;

[0023] Figure 2 yes Figure 1 Schematic diagram of a composite damper structure;

[0024] Figure 3 yes Figure 2 Schematic diagram of the structure of the magnetofluid variable cavity;

[0025] Figure 4 yes Figure 3 Internal structure diagram of the magnetohydrodynamic variable cavity

[0026] Figure 5a Figure 2 Schematic diagram of the structure of shape memory alloy wire bundle Figure 1 ;

[0027] Figure 5b Figure 2 Schematic diagram of the structure of shape memory alloy wire bundle Figure 2 ;

[0028] Figure 6 This is a schematic diagram of the phase transition energy dissipation mechanism of shape memory alloys in a specific embodiment of the present invention. Figure 1 ;

[0029] Figure 7 This is a schematic diagram of the phase transition energy dissipation mechanism of shape memory alloys in a specific embodiment of the present invention. Figure 2 ;

[0030] Figure 8 , Figure 1 Schematic diagram of energy-consuming nodes in stainless steel;

[0031] In the picture:

[0032] 101-Pressure sensor, 102-Concrete lining, 103-Basalt micro-tendon, 104-Stainless steel energy dissipation node, 105-Micro-grouting hole pipe, 106-Composite damper, 107-Shear surface, 301-Upper connecting steel plate, 302-Lower connecting steel plate, 303-Mounting hole, 304-Upper rubber pad, 305-Lower rubber pad, 306-Central flexible support column, 307-Shape memory alloy rod, 308-Threaded connection seat, 30 9-Excitation coil, 310-Magnetorheological fluid cavity, 311-Flexible deformation support plate, 401-Connecting hole, 402-Magnetorheological fluid cavity body, 403-Magnetorheological fluid magnetically controlled auxiliary stagnant flow baffle, 404-Cavity partition plate, 405-Cavity top plate, 406-Magnetorheological fluid cavity, 501-Shape memory alloy wire bundle, 502-Stainless steel sleeve, 503-Miniature displacement gauge, 504-Aerogel insulation layer, 901-Steel node body, 902-Energy dissipation node connection end. Detailed Implementation

[0033] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0034] like Figure 1 As shown, the embodiment provides a vibration reduction system for an underground reef limestone chamber, including an elastic bearing component, micro-grouting hole pipes, a composite rheostat, and a pressure sensor. The elastic bearing component includes basalt micro-tendons and stainless steel energy-dissipating nodes. Multiple basalt micro-tendons form a constraint network along the circumference and axial direction of the chamber on the inner wall of the chamber. The stainless steel energy-dissipating nodes are set at the intersections between the basalt micro-tendons. Multiple micro-grouting hole pipes are set along the axial direction of the chamber in the constraint network. The pressure sensor is embedded in the rock above the chamber. Multiple composite rheostats are set at the arch foot of the chamber.

[0035] This vibration damping system includes the following steps during its construction.

[0036] Step 1: Considering the high brittleness, well-developed structural surfaces, and easy cracking characteristics of the reef limestone chamber, basalt micro-tendon anchoring technology was adopted. Drilling and imaging were performed on the reef limestone surrounding the chamber to avoid dissolution fractures and weak interlayers. Basalt micro-tendons were anchored in intact rock sections using epoxy resin full-bonding anchoring, forming a multi-layered, uniformly distributed ring structure. In areas with well-developed dissolution, the spacing of the basalt micro-tendons was increased, and stainless steel energy-dissipating nodes were installed.

[0037] Step 2: Install a composite damping device of SMA fiber and magnetorheological fluid at the arch foot, sidewall, or predicted shear plane area of ​​the reef limestone chamber. The composite damping device consists of shape memory alloy rods arranged parallel to the longitudinal direction. Multiple shape memory alloy wire bundles (Ti-Ni-Cu SMA wires) are placed inside the shape memory alloy rods, symmetrically distributed in four groups of magnetorheological fluid cavities (MRF damping cavities). The two ends of the magnetorheological fluid cavities are fixed by rectangular flexible deformation plates (possessing a certain degree of deformability). The MRF damping cavities are filled with silicone oil-based magnetorheological fluid (containing 35% carbonyl iron particles), with electromagnetic coils wound around the outside, and connected to a sensing system consisting of accelerometers and displacement gauges.

[0038] Step 3: Set up the SMA fiber heating recovery system. Wrap a flexible PI heating pad around the SMA filament bundle, cover it with an aerogel insulation layer, connect it to the system control module via a temperature sensor, and set up overheat protection (temperature limit 100℃ + fuse thermal protector) to ensure that SMA phase change recovery can be triggered after an earthquake.

[0039] Step 4: System Coordination and Debugging. Simulate island and reef seismic waves (peak acceleration 0.4g) using a shaking table test to test the three-stage performance: In the minor earthquake stage (≤0.15g), the basalt microtendinous strain should be ≤0.3%; in the moderate earthquake stage (0.15g-0.4g), the SMA hyperelastic deformation should be 8-10%, and the MRF damping force should be adjustable within the range of 50-500kN; in the post-earthquake stage, when heated to a certain temperature, the SMA recovery strain should be greater than 3%, and the residual displacement less than 1mm. After debugging, perform waterproofing and corrosion-resistant treatment.

[0040] Furthermore, the inner side of the constraint network is lined with concrete, specifically C30 shotcrete lining.

[0041] Furthermore, the stainless steel energy-consuming node includes a node body and energy-consuming node connection ends, with multiple energy-consuming node connection ends located on the outside of the node body.

[0042] Furthermore, such as Figure 2 As shown, the composite rheostat includes an upper connecting steel plate, a lower connecting steel plate, an upper rubber pad, a lower rubber pad, a central flexible support column, a shape memory alloy rod, and a magnetorheological fluid variable cavity. The upper rubber pad is connected to the bottom of the upper connecting steel plate, and the lower rubber pad is connected to the top of the lower connecting steel plate. The central flexible support column, the shape memory alloy rod, and the magnetorheological fluid variable cavity are arranged between the upper and lower rubber pads.

[0043] Furthermore, the two ends of the central flexible support column are respectively connected to the center of the upper rubber pad and the center of the lower rubber pad; multiple magnetorheological fluid variable cavities are arranged around the majority of the central flexible support columns, and multiple shape memory alloy rods are arranged around the magnetorheological fluid variable cavities.

[0044] Furthermore, such as Figures 3-4As shown, an excitation coil is installed outside the magnetofluid variable cavity, and the two ends of the magnetofluid variable cavity are connected to the upper rubber pad and the lower rubber pad respectively through flexible deformation support plates.

[0045] Furthermore, the magnetorheological fluid variable excitation cavity is divided into a magnetorheological fluid variable cavity by a fluid cavity partition plate, and multiple magnetorheological fluid magnetically controlled auxiliary flow stagnant baffles are installed in the magnetorheological fluid variable cavity.

[0046] Furthermore, such as Figure 5a and Figure 5b As shown, the two ends of the shape memory alloy rod are connected to the upper rubber pad and the lower rubber pad respectively through threaded connectors; the shape memory alloy rod includes a stainless steel sleeve, a shape memory alloy wire bundle, and a micro displacement gauge; both the shape memory alloy wire bundle and the micro displacement gauge are set inside the stainless steel sleeve; the shape memory alloy wire bundle is Ti-Ni-Cu SMA wire, and the stainless steel sleeve is made of 316 stainless steel.

[0047] Furthermore, an aerogel insulation layer is provided on the inner side of the stainless steel sleeve, and a PI heating film is covered on the outside of the aerogel insulation layer.

[0048] Furthermore, multiple mounting holes are provided on both the upper and lower connecting steel plates, and multiple connection holes are provided on the flexible deformation support plate.

[0049] This system comprises multiple stages in its vibration reduction process, including three key stages: the elastic bearing stage of basalt micro-tendons, the synergistic energy dissipation stage of SMA fibers and magnetorheological fluid cavities, and the SMA heating phase transformation recovery and micro-grouting stage. In the first stage, circumferential and longitudinal basalt tendons form a flexible constraint network, improving the overall toughness of the chamber. Stainless steel energy-dissipating nodes are installed at tendon intersections. Under low-intensity seismic loads, these nodes can dissipate stress concentration at the basalt tendon nodes through their own inelastic deformation. The basalt tendons, with their high elastic modulus, dissipate seismic energy through significant elastic deformation. In the second stage, energy dissipation is primarily achieved by the SMA-MAF composite damper. When the seismic energy is large, causing plastic deformation in the reef limestone layer, the shape memory alloy wire initially undergoes austenitic elastic deformation, dissipating a small amount of seismic energy. As strain increases, the shape memory alloy wire gradually enters the phase transformation energy dissipation stage. Figure 6As shown, strain continues to increase, but the stress on the alloy wire increases slowly. During this stage, the shape memory alloy absorbs a large amount of energy, transforming from austenite to martensite. If seismic energy continues to be input during this stage, the shape memory alloy wire, after entering the martensitic hardening stage, can continue to undergo elastic deformation, increasing its absorption capacity. Simultaneously, the flexible variable support plates at the bottom and top of the magnetorheological fluid cavity deform accordingly. Based on the detected seismic intensity, the excitation coil outside the magnetorheological fluid cavity is adjusted to increase the current, thereby increasing the viscosity of the magnetorheological fluid, improving the damping force of the entire system, and maintaining a relatively small fluctuation in the equivalent damping force ratio of the entire system. In the third stage, based on data from the micro displacement gauge, the shape memory alloy wire is heated in stages and regions. The PI heating film + aerogel insulation layer can quickly raise the temperature around the alloy wire, and according to... Figure 7 The shape memory alloy's ability to recover upon heating reduces the size of earthquake-induced cracks. Combined with the shape memory alloy's restoring force and the pressure sensor readings, micro-grouting holes are opened for grouting, significantly reducing the magnitude of earthquake-induced cracks in the reef limestone.

[0050] Through a three-stage system design of "basalt micro-tendon elastic constraint - SMA-MRF synergistic energy dissipation - SMA heating phase change recovery," and by completely isolating the SMA from the external environment to ensure its performance is not weakened, and by introducing a silicone oil-based magnetorheological fluid (containing 35% carbonyl iron particles) as a damping fluid, its viscosity change rate is very small over a wide temperature range. This system ensures the structural integrity and functional continuity of underground chambers on coral islands and reefs in the South China Sea under earthquakes of different magnitudes. It also provides key engineering and technical support for the development and utilization of strategic spaces such as underground storage facilities and command and control systems on these islands and reefs, as well as for the safe service and long-term maintenance of underground spaces under strong earthquake conditions.

[0051] Other techniques in this embodiment are based on existing technologies.

[0052] This invention has been described through preferred embodiments. Those skilled in the art will understand that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of the invention. This invention is not limited to the specific embodiments disclosed herein; other embodiments falling within the scope of the claims are also within the protection scope of this invention.

Claims

1. A vibration damping system for underground caverns in reef limestone, characterized in that: The system includes an elastic bearing component, micro-grouting hole pipes, a composite rheostat, and a pressure sensor. The elastic bearing component comprises basalt micro-tendons and stainless steel energy-dissipating nodes. Multiple basalt micro-tendons form a constraint network along the circumferential and axial directions of the chamber on the inner wall of the chamber. The stainless steel energy-dissipating nodes are located at the intersections between the basalt micro-tendons. Multiple micro-grouting hole pipes are arranged along the axial direction of the chamber within the constraint network. The pressure sensor is embedded in the rock above the chamber. Multiple composite rheostats are located at the arch foot of the chamber. The composite rheostat includes an upper connecting steel plate, a lower connecting steel plate, an upper rubber pad, a lower rubber pad, a central flexible support column, a shape memory alloy rod, and a magnetorheological fluid variable cavity. The upper rubber pad is connected to the bottom of the upper connecting steel plate, and the lower rubber pad is connected to the top of the lower connecting steel plate. The central flexible support column, the shape memory alloy rod, and the magnetorheological fluid variable cavity are disposed between the upper and lower rubber pads. The two ends of the central flexible support column are respectively connected to the center of the upper rubber pad and the center of the lower rubber pad. Multiple magnetorheological fluid variable cavities are arranged around multiple central flexible support columns, and multiple shape memory alloy rods are arranged around the magnetorheological fluid variable cavities. An excitation coil is disposed outside the magnetorheological fluid variable cavity, and the two ends of the magnetorheological fluid variable cavity are respectively connected to the upper rubber pad and the lower rubber pad through flexible deformation support plates. The shape memory alloy rod includes a stainless steel sleeve, a shape memory alloy wire bundle, and a micro displacement gauge. The shape memory alloy wire bundle and the micro displacement gauge are both disposed inside the stainless steel sleeve. An aerogel insulation layer is provided on the inner side of the stainless steel sleeve, and a PI heating film is covered on the outside of the aerogel insulation layer.

2. The vibration damping system for underground reef limestone caverns according to claim 1, characterized in that: The inner side of the constraint network is lined with concrete.

3. The vibration damping system for underground reef limestone caverns according to claim 1, characterized in that: The stainless steel energy-consuming node includes a node body and energy-consuming node connection ends, with multiple energy-consuming node connection ends disposed on the outside of the node body.

4. The vibration damping system for underground reef limestone caverns according to claim 1, characterized in that: The magnetorheological fluid variable cavity is divided into multiple magnetorheological fluid magnetically controlled auxiliary flow stagnant baffles within the cavity.

5. The vibration damping system for underground reef limestone caverns according to claim 1, characterized in that: Both the upper connecting steel plate and the lower connecting steel plate have multiple mounting holes, and the flexible deformable support plate has multiple connection holes.

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