Anti-seismic protection structure of coral island limestone underground chamber and construction method

Abstract

The invention discloses an anti-seismic protection structure of a coral island reef limestone underground chamber and a construction method.The anti-seismic protection structure of the coral island reef limestone underground chamber comprises a chamber hole, an elastic shock insulation layer, a pouring layer, a shock insulation support, a viscous damping component and a mild steel damper; the seismic isolation support and the pouring layer bear vertical loads together, the viscous damping component and the side wall bear lateral confining pressure of reef limestone, under the earthquake effect, the elastic seismic isolation layer can preliminarily absorb earthquake energy, and after three-direction seismic waves are transmitted to the structure, the seismic energy of X-direction seismic waves and Y-direction seismic waves is consumed by the seismic isolation support at the bottom layer through vibration and friction, so that the seismic isolation effect is achieved. X-direction and Y-direction deformation and displacement of the chamber are reduced, Z-direction seismic waves absorb seismic energy through the seismic isolation support, so that energy continuously transmitted to the upper portion is avoided or reduced, and the vertical vibration response of the structure is relieved. At the arch crown part, the mild steel damper can absorb and dissipate energy through vibration and plastic deformation of an energy dissipation component arranged on the mild steel damper.

Description

Technical Field

[0001] The present application relates to the technical field of underground structure protection engineering, and particularly relates to an earthquake-resistant protection structure and construction method for an underground chamber in reef limestone of a coral island reef. Background Art

[0002] At present, relatively few studies have been conducted on earthquake isolation for underground chambers in reef limestone of the South China Sea coral island reefs, and there is no dedicated earthquake-proof structure for the properties of reef limestone. Considering that the South China Sea island reefs are located on the west side of the circum-Pacific seismic belt, and the seismic dynamic response characteristics of the coral island reef sites are quite different from those of other types of sites. In particular, the hydrogeological conditions and tidal effects where the island reefs are located significantly enhance the amplification effect of seismic waves. In addition, the unique physical and mechanical properties of reef limestone, such as high porosity, low density, low strength, and structural inhomogeneity, etc., result in the lack of earthquake-proof effect of traditional single isolation measures or ordinary isolation systems on underground chambers in reef limestone under earthquakes. Summary of the Invention

[0003] The present application aims to solve one of the above technical problems in the prior art. To this end, an embodiment of the present application provides an earthquake-resistant protection structure for an underground chamber in reef limestone of a coral island reef.

[0004] The embodiment of the present application also provides a construction method for the earthquake-resistant protection structure of an underground chamber in reef limestone of a coral island reef.

[0005] According to an embodiment of the first aspect of the present application, there is provided an earthquake-resistant protection structure for an underground chamber in reef limestone of a coral island reef, including

[0006] An underground chamber hole, on the inner surface of which an anchor shotcrete lining layer is provided;

[0007] An elastic isolation layer, laid on the surface of the anchor shotcrete lining layer;

[0008] A casting layer, provided on the surface of the isolation layer to form an underground chamber wall, and the underground chamber wall includes a bottom layer, side walls, and an arched top;

[0009] Isolation bearings, a plurality of which are arranged at intervals along the horizontal direction on the bottom layer;

[0010] Viscous damping members, a plurality of which are arranged at intervals along the extending direction of the underground chamber hole at the bottom of the side walls;

[0011] Soft steel dampers, which are provided at the top of the arched top.

[0012] The seismic protection structure of the underground chamber in the coral reef limestone has at least the following beneficial effects: When the seismic protection structure is in normal condition, the isolation bearings and the casting layer jointly bear the vertical load, and the viscous damping members and the side walls bear the lateral confining pressure of the reef limestone. Under the action of an earthquake, the elastic isolation layer can initially absorb the seismic energy. After the three-dimensional seismic waves are transmitted to the structure, the XY-direction seismic waves are dissipated by the vibration and friction of the isolation bearings at the bottom layer, reducing the XY-direction deformation and displacement of the chamber. The Z-direction seismic waves are absorbed by the isolation bearings to avoid or reduce the energy continuing to be transmitted upward and mitigate the vertical vibration response of the structure. At the arch top, the mild steel damper can absorb and dissipate energy through the vibration and plastic deformation of its energy dissipation components. An elastic isolation layer is provided between the reef limestone and the casting layer as a flexible connection, enhancing the performance of the overall isolation system, enabling the building to exhibit excellent seismic resistance under the action of an earthquake, and ensuring the safety of the structure and personnel. The isolation bearings, mild steel dampers, and viscous damping members provided on the casting layer act together to form an efficient and collaborative seismic resistance system. Among them, the isolation bearings, with their excellent elasticity and resilience, can absorb and disperse the vibration energy during an earthquake and reduce the displacement of the structure. The mild steel dampers utilize the vibration and plastic deformation ability of their energy dissipation components to dissipate the seismic energy and reduce the structural response. The viscous damping members provide additional damping force through their viscous characteristics to further reduce the vibration of the structure. This design scheme that comprehensively applies various seismic isolation technologies significantly improves the seismic performance of the building, enabling it to remain stable and reduce damage when facing a strong earthquake.

[0013] According to the seismic protection structure of the underground chamber in the coral reef limestone described in the first aspect embodiment of the present application, the elastic isolation layer is made of rubber, and the ratio of the thickness of the elastic isolation layer to the thickness of the casting layer is between 0.4 and 0.8.

[0014] According to the seismic protection structure of the underground chamber in the coral reef limestone described in the first aspect embodiment of the present application, the isolation bearing includes a lead core, an upper fixing member of the bearing, and a lower fixing member of the bearing. The lead core is vertically arranged. One end of the lead core is connected to a first shock absorption structure provided on the upper fixing member of the bearing, and the other end of the lead core is connected to the first shock absorption structure of the lower fixing member of the bearing, so that the upper fixing member of the bearing or the lower fixing member of the bearing can perform shock absorption adjustment in the horizontal direction. A second shock absorption structure is provided between the upper fixing member of the bearing and the lower fixing member of the bearing, so that the upper fixing member of the bearing or the lower fixing member of the bearing can be adjusted in the vertical direction. Among them, the second shock absorption structure partially wraps the lead core.

[0015] According to the seismic protection structure of the underground chamber in coral reef limestone of the first aspect embodiment of the present application, the first shock-absorbing structure includes a slider, a spring member, and shock-absorbing steel balls. A displacement groove for the slider to slide is provided on either the upper fixing member of the support or the lower fixing member of the support. The lead core is inserted into the center of the slider. The shock-absorbing steel balls and the spring member are arranged between the slider and the displacement groove. A plurality of the spring members and the shock-absorbing steel balls are provided, and the spring members are arranged in the direction of the central axis of the lead core.

[0016] According to the seismic protection structure of the underground chamber in coral reef limestone of the first aspect embodiment of the present application, the second shock-absorbing structure includes a rubber bearing and a plurality of steel plate members. The rubber bearing is sleeved on the lead core, and the plurality of steel plate members are arranged at intervals on the rubber bearing.

[0017] According to the seismic protection structure of the underground chamber in coral reef limestone of the first aspect embodiment of the present application, the viscous damping member includes an enclosed cavity formed by a plurality of steel members. The enclosed cavity is filled with a viscous body, and a deformation fixing plate is further arranged in the enclosed cavity. The setting direction of the deformation fixing plate is parallel to the setting direction of the side wall.

[0018] According to the seismic protection structure of the underground chamber in coral reef limestone of the first aspect embodiment of the present application, the mild steel damper includes an upper end plate, a lower end plate, a first energy dissipation structure, and a second energy dissipation structure. The first energy dissipation structure and the second energy dissipation structure are both arranged between the upper end plate and the lower end plate. A total of two groups of the first energy dissipation structures are provided, and the two groups of the first energy dissipation structures are respectively arranged at both ends of the upper end plate or the lower end plate. The second energy dissipation structure is located in the middle of the two groups of the first energy dissipation structures.

[0019] According to the seismic protection structure of the underground chamber in coral reef limestone of the first aspect embodiment of the present application, the first energy dissipation structure includes an upper connecting steel plate, a lower connecting steel plate, a coupling connecting body, a cylindrical coupling, an axial energy dissipation plate, and an inclined energy dissipation plate. The upper connecting steel plate and the lower connecting steel plate are respectively connected to the upper end plate and the lower end plate. The coupling connecting bodies are arranged on the opposite sides of the upper connecting steel plate and the lower connecting steel plate. At least one axial energy dissipation plate is arranged on each coupling connecting body. The axial energy dissipation plates on one coupling connecting body are connected to the axial energy dissipation plates on the other coupling connecting body through the cylindrical coupling. One end of the inclined energy dissipation plate is connected to the lower connecting steel plate, and the other end abuts against the upper end plate. The inclined energy dissipation plate inclines towards the second energy dissipation structure.

[0020] According to the seismic protection structure of the coral reef limestone underground chamber described in the first aspect of the present application, the second energy dissipation structure includes a middle connecting web, a central vertical energy dissipation plate, a transverse energy dissipation plate, and a cylindrical central rod. The cylindrical central rod is parallel to the upper end plate or the lower end plate. A plurality of the transverse energy dissipation plates are provided at both ends of the cylindrical central rod. Each of the transverse energy dissipation plates is provided with one of the central vertical energy dissipation plates. The central vertical energy dissipation plate is perpendicular to the upper end plate or the lower end plate. The central vertical energy dissipation plate is connected to the upper end plate or the lower end plate through the middle connecting web.

[0021] According to the embodiment of the second aspect of the present application, a construction method of the seismic protection structure of the coral reef limestone underground chamber described above is provided, including the following steps:

[0022] In the excavated chamber hole, shotcrete support technology is used to spray concrete on the surface of the reef limestone in the chamber hole to form an anchor-shotcrete lining layer;

[0023] Lay an elastic isolation layer on the surface of the anchor-shotcrete lining layer;

[0024] Pour concrete on the surface of the elastic isolation layer to form a pouring layer. The pouring layer forms a chamber wall. The chamber wall includes a bottom layer, side walls, and an arched roof;

[0025] Among them, before forming the bottom layer, a number of isolation bearings are arranged at intervals in the horizontal direction at the formation position of the bottom layer, and the deviation value between the levelness of the isolation bearing and the inclination of the horizontal plane is not greater than 2%;

[0026] Before forming the side walls, a number of viscous damping members are arranged at intervals along the extension direction of the chamber hole;

[0027] When forming the arched roof, a steel arch frame is required for fixation, and a mild steel damper is installed at the top of the arch.

[0028] Additional aspects and advantages of the present application will be given in part in the following description, become apparent in part from the following description, or be understood through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The present application will be further described below in conjunction with the drawings and embodiments;

[0030] Figure 1 is the front view of the coral reef limestone underground chamber hole in the embodiment of the present application;

[0031] Figure 2 is the side view of the coral reef limestone underground chamber hole in the embodiment of the present application;

[0032] Figure 3It is a schematic diagram of the structure of the seismic isolation bearing in the embodiments of the present application Figure 1 ;

[0033] Figure 4 It is a schematic diagram of the structure of the seismic isolation bearing in the embodiments of the present application Figure 2 ;

[0034] Figure 5 It is a schematic diagram of the structure of the mild steel damper in the embodiments of the present application;

[0035] Figure 6 It is a schematic diagram of the structure of the viscous damping member in the embodiments of the present application Figure 1 ;

[0036] Figure 7 It is a schematic diagram of the structure of the viscous damping member in the embodiments of the present application Figure 2 .

[0037] Reference numerals: 1 - mild steel damper, 2 - elastic seismic isolation layer, 3 - seismic isolation bearing, 4 - viscous damping member, 11 - bottom layer, 12 - side wall, 13 - arch top, 101 - upper end plate, 102 - lower end plate, 103 - upper connecting steel plate, 104 - lower connecting steel plate, 105 - cylindrical center rod, 106 - inclined energy dissipation plate, 107 - coupling connecting body, 108 - cylindrical coupling, 109 - axial energy dissipation plate, 110 - transverse energy dissipation plate, 111 - central vertical energy dissipation plate, 112 - connecting bolt hole, 113 - end plate fixing bolt hole, 114 - middle connecting web, 301 - lead core, 302 - steel plate part, 303 - rubber bearing, 304 - lower fixing part of the bearing, 305 - upper fixing part of the bearing, 306 - embedded steel plate at the bottom of the tunnel, 307 - bolt connection hole, 308 - spring part, 309 - shock-absorbing steel ball, slider 310, 401 - side steel plate, 402 - deformation fixing plate, 403 - bottom connection bolt hole, 404 - upper cross beam, 405 - lower cross beam, 406 - front sealing steel plate. Detailed Description of the Invention

[0038] This part will describe in detail the specific embodiments of the present application. The preferred embodiments of the present application are shown in the drawings. The role of the drawings is to supplement the description in the text part of the specification, enabling people to intuitively and vividly understand each technical feature and the overall technical solution of the present application, but it cannot be understood as a limitation on the protection scope of the present application.

[0039] In the description of the present application, it should be understood that the orientation or positional relationship indicated by terms such as up, down, front, back, left, right, etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application.

[0040] In the description of this application, "several" means one or more, "multiple" means more than two, and terms such as "greater than", "less than", "exceeding", etc. are understood not to include the corresponding number, while terms such as "above", "below", "within", etc. are understood to include the corresponding number. If "first" and "second" are described, they are only used to distinguish technical features and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features or implicitly specifying the sequence of the indicated technical features.

[0041] In the description of this application, unless otherwise clearly defined, terms such as "set", "installed", "connected", etc. should be understood in a broad sense, and those skilled in the art can reasonably determine the specific meanings of the above terms in this application in combination with the specific content of the technical solution.

[0042] After the death of the reef-building coral colonies, coral reefs are formed by the mutual cementation of their remains, various reef-attached organisms, some shellfish and algae, etc. after the combined action of geological sedimentation, biological destruction and marine dynamics. Reef limestone is the diagenetic part at the lower part of the coral reef and is the main part of the coral island reef rock mass, and its main mineral component is calcium carbonate. Biogenic coral reef rock has physical and mechanical properties such as low density, easy to break, low strength, high porosity, and high compressibility, which make reef limestone very different from conventional terrigenous rocks.

[0043] Coral islands and reefs are almost the only type of land territory in China's South China Sea waters and are the most important and unique geological bodies in the South China Sea. As the main body of coral reef rock and soil, reef limestone is the foundation and foothold for the construction of island reef projects. The construction of island reef projects not only lies in the construction of ground buildings, airports, ports and other facilities, but the development and construction of the underground space of island reefs also have the same strategic status. The development of underground chambers can improve resource utilization and space expansion, and improve the ability to adapt to the environment and protect equipment.

[0044] The strategy of building a maritime power is a major strategic deployment put forward by China in the face of the 21st-century marine era, aiming to promote the development of the marine economy, the progress of marine science and technology, and the rational utilization of marine resources, so as to achieve the sustainable development of marine resources and the effective maintenance of marine rights and interests. Against this strategic background, it is of great practical significance and strategic value to carry out research on the seismic resistance technology of island reef chambers. First of all, with the implementation of the strategy of "building a maritime power", the construction of marine engineering in the South China Sea, represented by land reclamation and island reef construction, has been accelerating, and the South China Sea area of China is seismically active, posing a severe challenge to the long-term stability of island reef sites.

[0045] The overlying coral sand on reef limestone, as the main component material of the island reef, has a direct impact on the seismic response. Research shows that the characteristics of the reduction of dynamic shear modulus and the increase of damping ratio of coral sand are crucial for seismic response analysis. The engineering geological characteristics of the island reef site, including the basin-like structure of reef limestone and the special physical and mechanical properties of the rock and soil mass of the island reef, have a significant impact on the seismic response. These characteristics need to be considered in seismic design.

[0046] The South China Sea island reefs are located on the west side of the circum-Pacific seismic belt. Earthquakes of magnitude 6 or above have occurred in history, and they face the risk of earthquake damage under high-intensity earthquakes. The porosity of reef limestone on coral islands and reefs is as high as 45%-55%, much higher than that of ordinary rocks. Its natural longitudinal wave velocity is 2780-3693 m / s, and the saturated longitudinal wave velocity is 3000-3630 m / s. Parameters such as tensile and compressive strength, elastic modulus, and Poisson's ratio also differ from ordinary rocks. Due to the high porosity, complex waveform, special seismic wave propagation and amplification process, and failure along the growth line and high residual strength of reef limestone, it shows unique properties in seismic response. Therefore, it is highly necessary to carry out seismic protection for underground chambers in reef limestone, and the special properties of reef limestone need to be taken into account.

[0047] In summary, for the construction and seismic protection of underground chambers in reef limestone of island reefs, it is urgent to develop a seismic protection structure for underground chambers in coral island reef reef limestone that is three-dimensional, all-round, multi-layered, has good integrity, is convenient for construction, has good durability, and has high safety, so as to ensure the reduction of the structural response and the improvement of safety of the underground chambers under earthquakes.

[0048] Referring to Figure 1 and Figure 2 The seismic protection structure of the underground chamber of coral island reef reef limestone provided by this application includes a chamber hole, an elastic isolation layer 2, a pouring layer, isolation bearings 3, viscous damping members 4, and mild steel dampers 1.

[0049] Among them, an anchor-shotcrete lining layer and mild steel dampers 1 are arranged on the inner surface of the chamber hole, and the mild steel dampers 1 are arranged at the top of the vault 13. Due to the high porosity, high permeability, and relatively weak compressive strength of the reef limestone chamber hole, first, the shotcrete support technology is adopted to spray concrete on the surface of the reef limestone around the chamber hole to enhance its structural strength and form an anchor-shotcrete lining layer with high strength and flatness.

[0050] On the surface of the reef limestone concrete mixture treated with shotcrete, an elastic isolation layer 2 needs to be laid. This step provides buffering and protection for the subsequent structure and increases the isolation effect of the system.

[0051] The casting layer is arranged on the surface of the seismic isolation layer to form the chamber wall. Among them, the chamber wall includes a bottom layer 11, side walls 12, and an arched vault 13. A number of seismic isolation bearings 3 are arranged at intervals along the horizontal direction of the bottom layer 11; a number of viscous damping members 4 are arranged at intervals along the extension direction of the chamber hole at the bottom of the side walls 12; a mild steel damper 1 is arranged at the top of the vault 13.

[0052] The underground chamber is located in the reef limestone layer. First, considering that the reef limestone has low strength and is lower than that of other continental margin rocks, it is necessary to use reinforced concrete to construct the underground chamber to ensure sufficient structural strength and safety of the chamber. For reinforced concrete, considering the installation of shock absorption devices during the casting process, it is necessary to use layered casting. Attention should be paid to the strengthening at the layered joints to ensure the integrity of the chamber, and a double-layer reinforced concrete permanent internal support is adopted.

[0053] An elastic seismic isolation layer 2 is laid around the reinforced concrete casting layer to wrap the entire underground structure. The elastic seismic isolation layer 2 is made of rubber. Among them, the material of the elastic seismic isolation layer 2 is one or a combination of ethylene propylene diene monomer rubber, silicone rubber, chloroprene rubber, and natural rubber. The ratio of the thickness of the elastic seismic isolation layer 2 to the thickness of the casting layer is between 0.4 and 0.8.

[0054] A mild steel damper 1 is arranged in the vault 13. The mild steel damper 1 should be arranged at the position with a larger vibration amplitude according to the scale of the underground chamber; the layout of the mild steel damper 1 in the plane should follow the principles of "uniformity, dispersion, and symmetry"; the mild steel damper 1 is arranged along the axial direction of the chamber hole on the roof slab. The stiffness and maximum deformation of the mild steel damper 1 depend on the lateral stiffness of the reef limestone mass and the maximum allowable deformation of the underground chamber. Among them, the mild steel damper 1 is a displacement-type damper.

[0055] The bottom layer 11 adopts seismic isolation bearings 3. In the embodiment of the present application, the seismic isolation bearing 3 is a lead-core 301 sandwich composite seismic isolation bearing in which a rubber cushion layer and a spring support are connected in parallel, which can effectively isolate low-frequency and high-frequency vibrations, and has stable performance and long service life. The lead core 301 dissipates seismic energy by using its elastoplastic properties during the ground motion process, effectively reducing the seismic response of the structure. The seismic isolation bearing 3 can meet the different requirements of the reef limestone chamber for performance such as vertical stiffness, lateral deformation, damping, and durability by adjusting the parameters of the rubber cushion layer and the spring support.

[0056] The side walls 12 are provided with viscous damping members 4, which can provide a large damping force for the whole chamber, enhance the lateral force resistance ability of the building, and reduce the damage of the earthquake to the building structure.

[0057] When the anti-seismic protection structure is in normal condition, the isolation bearing 3 and the casting layer jointly bear the vertical load, and the viscous damping member 4 and the side wall 12 bear the lateral confining pressure of the reef limestone. Under the action of an earthquake, the elastic isolation layer 2 can initially absorb the seismic energy. After the three-dimensional seismic waves are transmitted to the structure, the XY-direction seismic waves are dissipated by the vibration and friction of the isolation bearings 3 at the bottom layer 11, reducing the XY-direction deformation and displacement of the chamber. The Z-direction seismic waves are absorbed by the isolation bearings 3 to avoid or reduce the energy continuing to be transmitted upward and mitigate the vertical vibration response of the structure. In the arch top 13 part, the mild steel damper 1 can absorb and dissipate energy through the vibration and plastic deformation of its own energy-dissipating components.

[0058] An elastic isolation layer 2 is provided between the reef limestone and the casting layer as a flexible connection, enhancing the performance of the overall isolation system, enabling the building to exhibit excellent anti-seismic effects under the action of an earthquake, and ensuring the safety of the structure and personnel. The isolation bearings 3, mild steel dampers 1, and viscous damping members 4 provided on the casting layer act together to form an efficient and collaborative anti-seismic system. Among them, the isolation bearing 3, with its excellent elasticity and resilience, can absorb and disperse the vibration energy during an earthquake, reducing the displacement of the structure. The mild steel damper 1 dissipates the seismic energy and reduces the structural response by utilizing the vibration and plastic deformation capabilities of its own energy-dissipating components. The viscous damping member 4 provides additional damping force through its viscous characteristics to further reduce the vibration of the structure. This design scheme that comprehensively uses various isolation technologies significantly improves the anti-seismic performance of the building, enabling it to remain stable and reduce damage when facing strong earthquakes.

[0059] In some specific embodiments, such as Figure 3 and Figure 4 shown, the isolation bearing 3 includes a lead core 301, an upper fixing member 305 of the bearing, and a lower fixing member 304 of the bearing. The lead core 301 is vertically arranged. One end of the lead core 301 is connected to a first shock-absorbing structure provided on the upper fixing member 305 of the bearing, and the other end of the lead core 301 is connected to a first shock-absorbing structure provided on the lower fixing member 304 of the bearing, so that the upper fixing member 305 or the lower fixing member 304 of the bearing can perform shock-absorbing adjustment in the horizontal direction. A second shock-absorbing structure is provided between the upper fixing member 305 and the lower fixing member 304 of the bearing, so that the upper fixing member 305 or the lower fixing member 304 of the bearing can be adjusted in the vertical direction. Among them, the second shock-absorbing structure partially wraps the lead core 301.

[0060] Specifically, the first shock-absorbing structure includes a slider 310, a spring member 308, and shock-absorbing steel balls 309. Both the upper fixing member 305 of the support and the lower fixing member 304 of the support are provided with displacement grooves for the slider 310 to slide. The lead core 301 is inserted into the center of the slider 310. Shock-absorbing steel balls 309 and spring members 308 are arranged between the slider 310 and the displacement groove. Multiple spring members 308 and shock-absorbing steel balls 309 are provided, and the spring members 308 are arranged in the direction of the central axis of the lead core 301. The first shock-absorbing structure forms a spring support. The second shock-absorbing structure includes a rubber support 303 and multiple steel plate members 302. The rubber support 303 is sleeved on the lead core 301, and multiple steel plate members 302 are arranged at intervals on the rubber support 303.

[0061] Among them, the lead core 301 of the seismic isolation bearing 3 is inserted into the rubber support 303. The lower fixing member 304 and the upper fixing member 305 of the support provide a solid foundation for the support. The embedded steel plate 306 and the bolt connection holes 307 at the bottom of the tunnel ensure a firm connection with the bottom layer 11. The spring members 308 arranged in the XY direction and the shock-absorbing steel balls 309 arranged in the XY direction provide additional lateral and longitudinal shock-absorbing capabilities for the system.

[0062] It should be noted that a part of the lead core 301 is in the rubber support 303, and the lead core 301 has the following properties: ① Energy dissipation through elastoplastic deformation: The lead core has a low yield strength and good fatigue performance. During an earthquake, it yields first and enters the plastic deformation stage, absorbing a large amount of energy and reducing the transmitted energy. Its hysteretic characteristics are stable, and it continuously dissipates energy during the repeated loading and unloading process; ② Energy dissipation through recrystallization: After the lead is deformed, it can recrystallize. The deformation energy stored in the grains during deformation is converted into other forms of energy and released, playing a role in energy dissipation; ③ Improving the damping of the bearing: The lead core 301 significantly improves the damping performance of the seismic isolation bearing 3, and the vibration amplitude decays faster during vibration, reducing the duration and intensity; ④ It can increase the initial stiffness and yield strength of the seismic isolation bearing 3; The lead core 301 increases the initial stiffness and yield strength of the rubber support 303, generates a larger reaction force under a smaller external force, better resists external forces, reduces structural deformation and vibration. At the same time, the high yield strength enables the lead core to bear a greater load during plastic deformation, enhancing the energy dissipation capacity.

[0063] The main body of the rubber support 303 can deform, that is, the upper fixing member 305 of the support can move towards the lower fixing member 304 of the support. The rubber support 303 has the following properties: ① Energy dissipation through flexible deformation: When the rubber is deformed by an external force, the molecular chains slip and rearrange, converting mechanical energy into heat energy and other forms of energy for dissipation. For example, the rubber support deforms and absorbs energy during an earthquake or under vehicle loads. ② Energy dissipation through damping characteristics: When the rubber is subjected to a periodic external force, internal friction and interaction within the molecules cause hysteretic deformation, converting the vibration energy into heat energy and dissipating it. High-damping rubber dissipates energy significantly in a wide frequency range. ③ Energy dissipation through stress relaxation: When the rubber is subjected to a constant strain, the stress decreases with time. The initial stress is large, and then the molecular structure adjusts and relaxes, releasing energy in the form of heat and relieving stress concentration.

[0064] The spring member 308 provides the rubber bearing 303 and the lead core 301 with the supporting ability in the XY plane, increasing the overall stability. Through its elastic deformation, the spring member 308 can absorb energy and increase the shock absorption ability of the seismic isolation bearing 3 in the XY plane.

[0065] The shock-absorbing steel balls 309 have the following properties: ① Rolling energy consumption: When vibrating, the steel balls roll in the annular gap formed by the displacement groove and the slider 310, converting the vibration energy into rolling kinetic energy and elastic potential energy, reducing the amplitude of vibration transmission. ② Frictional energy consumption: During rolling, the steel balls generate friction with the wall of the annular gap formed by the displacement groove and the slider 310, converting part of the vibration energy into heat and dissipating it. The magnitude of the frictional force is related to materials, surface roughness, lubrication conditions, etc.

[0066] When the underground chamber is in normal condition, the seismic isolation bearing 3 and the pouring layer jointly bear the vertical load, and the viscoelastic damping member 4 and the side wall of the chamber bear the lateral confining pressure of the reef limestone. Under the action of an earthquake, the elastic seismic isolation layer 2 can initially absorb the seismic energy. After the three-directional seismic waves are transmitted to the structure, the XY-directional seismic waves are consumed by the elastic deformation of the spring member 308 arranged in the XY direction and the vibration and friction of the shock-absorbing steel balls 309 arranged in the XY direction of the seismic isolation bearing 3 at the bottom layer 11, reducing the XY-directional deformation and displacement of the underground chamber. The Z-directional seismic waves are absorbed by the elasticity of the rubber bearing 303 and the plasticity of the bearing lead core 301 of the seismic isolation bearing 3 to avoid or reduce the energy continuing to be transmitted upward and mitigate the vertical vibration response of the structure.

[0067] Among them, the seismic isolation bearing 3 can consume part of the vibration energy through the viscoelasticity of the rubber bearing 303 as the main body, effectively isolating and absorbing vibrations. The spring member 308 arranged in the XY direction and the shock-absorbing steel balls 309 arranged in the XY direction, which are symmetrically distributed on the upper and lower parts of the bearing, adjust the appropriate spring stiffness when bearing the XY-directional seismic waves, absorb energy through elastic deformation, and are evenly distributed with multiple springs on one side, reducing the load on a single spring and improving its service life; the shock-absorbing steel balls 309 absorb the seismic energy through their own vibration, and under the action of an earthquake, mutual extrusion, relative frictional movement between the steel balls and friction between the steel balls and the side wall occur, converting the vibration energy into heat to achieve dynamic vibration energy absorption.

[0068] In some embodiments, as Figure 5 shown, the mild steel damper 1 includes an upper end plate 101, a lower end plate 102, a first energy-consuming structure, and a second energy-consuming structure. The first energy-consuming structure and the second energy-consuming structure are both arranged between the upper end plate 101 and the lower end plate 102. There are two groups of the first energy-consuming structures, and the two groups of the first energy-consuming structures are respectively arranged at both ends of the upper end plate 101 or the lower end plate 102, and the second energy-consuming structure is in the middle of the two groups of the first energy-consuming structures.

[0069] Specifically, the first energy-consuming structure includes an upper connecting steel plate 103, a lower connecting steel plate 104, a coupling connecting body 107, a cylindrical coupling 108, an axial energy-consuming plate 109, and an inclined energy-consuming plate 106. The upper connecting steel plate 103 and the lower connecting steel plate 104 are respectively connected to the upper end plate 101 and the lower end plate 102. Coupling connecting bodies 107 are provided on the opposite sides of the upper connecting steel plate 103 and the lower connecting steel plate 104. At least one axial energy-consuming plate 109 is provided on each coupling connecting body 107. The axial energy-consuming plates 109 on one coupling connecting body 107 are connected to the axial energy-consuming plates 109 on the other coupling connecting body 107 through the cylindrical coupling 108. One end of the inclined energy-consuming plate 106 is connected to the lower connecting steel plate 104, and the other end abuts against the upper end plate 101. The inclined energy-consuming plate 106 is inclined towards the second energy-consuming structure.

[0070] The second energy-consuming structure includes a middle connecting web 114, a central vertical energy-consuming plate 111, a transverse energy-consuming plate 110, and a cylindrical central rod 105. The cylindrical central rod 105 is parallel to the upper end plate 101 or the lower end plate 102. A plurality of transverse energy-consuming plates 110 are provided at both ends of the cylindrical central rod 105. Each transverse energy-consuming plate 110 is provided with a central vertical energy-consuming plate 111. The central vertical energy-consuming plate 111 is perpendicular to the upper end plate 101 or the lower end plate 102. The central vertical energy-consuming plate 111 is connected to the upper end plate 101 or the lower end plate 102 through the middle connecting web 114.

[0071] In the mild steel damper 1, the upper end plate 101 and the lower end plate 102 are respectively located at the top and bottom of the structure. The upper connecting steel plate 103 and the lower connecting steel plate 104 are used to connect different parts to ensure the stability of the structure. The cylindrical central rod 105 serves as the core support. The inclined energy-consuming plate 106 and the coupling connecting body 107 act together on the energy-consuming mechanism to reduce the energy transfer of the structure under external forces such as earthquakes. The cylindrical coupling 108 and the axial energy-consuming plate 109 further enhance the energy-consuming capacity of the damper. The design of the transverse energy-consuming plate 110 and the central vertical energy-consuming plate 111 enables the damper to effectively absorb and dissipate energy in multiple directions. The connecting bolt holes 112 and the end plate fixing bolt holes 113 facilitate installation and fixing. The middle connecting web 114 strengthens the overall stiffness of the structure.

[0072] Among them, the extending direction of the long side of the mild steel damper 1 is the X direction, the wide side direction is the Y direction, and the thickness direction is the Z direction.

[0073] The middle connecting web 114, the upper connecting steel plate 103, and the lower connecting steel plate 104 do not play an energy absorption role, but only fix each energy absorption plate to the upper and lower end plates. The first energy absorption structure and the second energy absorption structure are parallel parts, which can absorb energy simultaneously during the earthquake action process. The specific energy absorption depends on the direction of the earthquake wave, among which the inclined energy absorption plate 106 and the axial energy absorption plate 109 absorb the earthquake energy in the z direction and the x direction; the transverse energy absorption plate 110 absorbs the earthquake energy in the z direction and the y direction; and the central vertical energy absorption plate 111 absorbs the earthquake energy in the y direction.

[0074] The properties of mild steel are as follows: ① Plastic deformation energy dissipation: Utilize the plastic deformation capacity of mild steel to absorb and dissipate energy under the action of external forces such as earthquakes. ② Hysteresis performance energy dissipation: Show stable hysteresis performance, repeatedly absorb and release energy, and reduce the dynamic response of the structure. ③ Displacement-related energy dissipation: Energy dissipation capacity is closely related to structural displacement, and energy dissipation capacity increases when displacement increases. ④ Viscous resistance energy dissipation: When mild steel plastically deforms, it is inhibited by viscous resistance, forming viscous damping and consuming more energy.

[0075] The inclined energy dissipation plate 106, due to its special arrangement, needs to withstand axial force while resisting lateral force, and is made of low yield point soft steel with a yield strength of 100MPa to 190MPa. This material can enter plastic deformation at a lower stress level, thereby providing effective energy dissipation.

[0076] The axial energy dissipation plate 109 mainly bears the axial load and is also made of low yield point mild steel with a yield strength of 100MPa to 190MPa. Such a yield strength range can ensure that the energy dissipation mechanism can be activated under a relatively small deformation, providing a good energy dissipation effect.

[0077] The transverse energy dissipation plate 110 needs to resist the transverse load, and considering its energy dissipation requirements, a low yield point soft steel with a yield strength of 160 MPa is used. This material can provide a larger plastic deformation capacity, thereby absorbing more energy under earthquake action.

[0078] The central vertical energy dissipation plate 111 is a key energy dissipation component in the structure, and the selection of its yield strength is crucial to the energy dissipation performance of the entire structure. Low yield point soft steel with a yield strength of 160MPa-225MPa is used to ensure sufficient energy dissipation limit under the action of a higher magnitude earthquake to maintain the stability and safety of the structure.

[0079] Among them, the cylindrical coupling 108 allows the axial energy absorbing plate 109 to rotate to a certain extent, but the rotation only occurs in a large earthquake. The energy absorbing plate itself cannot meet the energy consumption requirements through vibration, and a certain degree of rotation can occur. The coupling connector 107 cannot rotate, and serves to fix the axial energy absorbing plate 109 on the upper and lower connecting plates. The inclined energy absorbing plate 106 cannot rotate.

[0080] Among them, the cylindrical central rod 105 is hinged to the transverse energy dissipation plate. Generally, it is the same as consolidation, that is, low rotational freedom: the hinge has a low rotational freedom and usually remains relatively fixed, only allowing partial rotation under extreme conditions. It rotates to a certain extent under extreme rotations such as major earthquakes to improve the energy dissipation limit of the mild steel damper.

[0081] When an earthquake occurs, at the arch top 13 of the underground chamber, the mild steel damper 1 absorbs and dissipates energy through the self-vibration and plastic deformation of the inclined energy dissipation plate 106, axial energy dissipation plate 109, transverse energy dissipation plate 110, and central vertical energy dissipation plate 111. After the earthquake ends, the isolation bearing 3 returns to its original position, and the energy dissipation plates of the mild steel damper 1 return to their pre-deformation shapes and positions and provide horizontal and vertical restoring forces to eliminate the residual displacement of the underground chamber.

[0082] Among the mild steel damper 1 and isolation bearing 3 at the top, the mild steel damper 1 combines energy dissipation through the inclined energy dissipation plate 106, transverse energy dissipation plate 110, axial energy dissipation plate 109, and central vertical energy dissipation plate 111 to achieve energy dissipation and absorption of three-directional seismic waves and reduce the dynamic response of the underground chamber under earthquake action.

[0083] In some embodiments, such as Figure 6 and Figure 7 shown, the viscous damping member 4 includes a sealed cavity formed by multiple steel parts. The sealed cavity is filled with a viscous body, and a deformation fixing plate 402 is also arranged in the sealed cavity. The setting direction of the deformation fixing plate 402 is parallel to the setting direction of the side wall 12.

[0084] Among them, the steel parts include side steel plates 401, upper cross beam 404, lower cross beam 405, and front sealing steel plates 406. Two side steel plates 401 are arranged oppositely, and two front sealing steel plates 406 are arranged oppositely. The side steel plates 401 and front sealing steel plates 406 form the side walls of the sealed cavity, and the upper cross beam 404 and lower cross beam 405 respectively form the bottom and top of the sealed cavity. The two ends of the deformation fixing plate 402 are respectively connected to the upper cross beam 404 and lower cross beam 405.

[0085] The side steel plates 401 and deformation fixing plate 402 in the viscous damping member 4 act together on the side of the structure, and a highly viscous viscous body is injected into the sealed space. During an earthquake, the viscous material undergoes shear deformation, and the internal friction generated during the material flow does work to consume energy. The bottom connection bolt holes 403112, upper cross beam 404, and lower cross beam 405 form the lateral support system of the structure. The front sealing steel plates 406 serve as the front protection of the structure, enhancing the overall protection performance.

[0086] A viscous damping member 4 is provided on the side wall 12 of the underground chamber. The liquid inside the viscous damping member 4 provides a large damping force for the entire structure without affecting the vibration period and mode of the whole structure, can significantly reduce the seismic response of the structure, considers the stability and safety of the underground chamber under rare earthquakes, and improves the seismic protection level of the chamber.

[0087] The seismic protection structure applicable to the coral island reef limestone underground chamber proposed in this application, through comprehensive and systematic three-directional seismic wave absorption measures for the structure, effectively reduces the response of the structure under earthquakes of different magnitudes, ensures that the underground project on the South China Sea coral islands can be used and maintained normally under earthquake action, and provides engineering technical references for the development of the underground space on the coral islands and the safety and stability of more available spaces used under earthquake action.

[0088] An isolation bearing 3 is provided between the shotcrete lining and the chamber wall, innovatively constructing a protection system of reef limestone - isolation layer - underground structure. This isolation layer, as a solid barrier, efficiently isolates the underground chamber from the reef limestone body, greatly weakening and transforming the impact force and mode of the earthquake on the structure. The core purpose of this design is to greatly reduce the vibration response of the underground structure, thereby significantly improving the overall seismic performance and safety of the building.

[0089] This application also provides a construction method for the above-mentioned seismic protection structure of the coral island reef limestone underground chamber, including the following steps:

[0090] In the excavated chamber hole, shotcrete support technology is used to spray concrete on the surface of the reef limestone in the chamber hole to form a shotcrete lining layer. When applying shotcrete technology on the reef limestone, the special properties of the reef limestone, such as easy cementation of particles, loose and easy to break, low hardness, high porosity, etc., can be improved to form a shotcrete lining layer with high bearing capacity and good stability;

[0091] Lay an elastic isolation layer 2 on the surface of the shotcrete lining layer;

[0092] Pour concrete on the surface of the elastic isolation layer 2 to form a pouring layer, and the pouring layer forms the chamber wall. The chamber wall includes a bottom layer 11, a side wall 12, and an arched top 13;

[0093] Among them, before forming the bottom layer 11, a number of isolation bearings 3 are arranged at intervals in the horizontal direction at the forming position of the bottom layer 11, and the deviation value between the levelness of the isolation bearing 3 and the inclination of the horizontal plane is not greater than 2%;

[0094] Before forming the side wall 12, a number of viscous damping members 4 are arranged at intervals along the extension direction of the chamber hole;

[0095] When forming the vault 13, it is necessary to use a steel arch frame for fixation, and a soft steel damper 1 is installed at the top of the vault 13.

[0096] The embodiments of the present application have been described in detail above in conjunction with the accompanying drawings. However, the present application is not limited to the above embodiments. Within the scope of knowledge possessed by those of ordinary skill in the art, various changes can be made without departing from the purpose of the present application.

Claims

1. An earthquake-resistant protection structure for an underground chamber in coral reef limestone, characterized in that: including a chamber hole, with an anchor shotcrete lining layer provided on the inner surface of the chamber hole; an elastic isolation layer, laid on the surface of the anchor shotcrete lining layer; a pouring layer, provided on the surface of the isolation layer to form a chamber wall, and the chamber wall includes a bottom layer, side walls, and an arched vault; isolation bearings, with a plurality of the isolation bearings arranged at intervals along the horizontal direction on the bottom layer; viscous damping members, with a plurality of the viscous damping members arranged at intervals along the extending direction of the chamber hole at the bottom of the side walls; yielding steel dampers, with the yielding steel dampers provided at the top of the vault.

2. The anti-seismic protection structure of the underground chamber in coral reef limestone according to claim 1, wherein: The elastic isolation layer is made of rubber, and the ratio of the thickness of the elastic isolation layer to the thickness of the pouring layer is between 0.4 and 0.

8.

3. The anti-seismic protection structure of the underground chamber in coral reef limestone according to claim 1, wherein: The isolation bearing includes a lead core, an upper fixing member of the bearing, and a lower fixing member of the bearing. The lead core is arranged vertically. One end of the lead core is connected to a first shock-absorbing structure provided on the upper fixing member of the bearing, and the other end of the lead core is connected to the first shock-absorbing structure of the lower fixing member of the bearing, so that the upper fixing member of the bearing or the lower fixing member of the bearing can perform shock-absorbing adjustment in the horizontal direction. A second shock-absorbing structure is arranged between the upper fixing member of the bearing and the lower fixing member of the bearing, so that the upper fixing member of the bearing or the lower fixing member of the bearing can perform adjustment in the vertical direction. Among them, the second shock-absorbing structure wraps a part of the lead core.

4. The aseismic protection structure of the underground chamber in coral reef limestone according to claim 3, characterized in that: The first shock-absorbing structure includes a slider, a spring member, and shock-absorbing steel balls. Both the upper fixing member of the bearing or the lower fixing member of the bearing are provided with displacement grooves for the slider to slide. The lead core is inserted into the center of the slider. The shock-absorbing steel balls and the spring member are arranged between the slider and the displacement groove. A plurality of the spring members and the shock-absorbing steel balls are provided, and the spring members are arranged towards the central axis direction of the lead core.

5. The anti-seismic protection structure of the underground chamber in coral reef limestone according to claim 3, characterized in that: The second shock-absorbing structure includes a rubber bearing and a plurality of steel plate members. The rubber bearing is sleeved on the lead core, and the plurality of steel plate members are arranged at intervals on the rubber bearing.

6. The aseismic protection structure of the underground chamber in coral reef limestone according to claim 1, characterized in that: The viscous damping member includes a sealed cavity formed by a plurality of steel members. The sealed cavity is filled with a viscous body, and a deformation fixing plate is further arranged in the sealed cavity. The setting direction of the deformation fixing plate is parallel to the setting direction of the side wall.

7. The anti-seismic protection structure of the underground chamber in coral reef limestone according to claim 1, wherein: The yielding steel damper includes an upper end plate, a lower end plate, a first energy-dissipating structure, and a second energy-dissipating structure. Both the first energy-dissipating structure and the second energy-dissipating structure are arranged between the upper end plate and the lower end plate. Two groups of the first energy-dissipating structures are provided in total, and the two groups of the first energy-dissipating structures are respectively arranged at both ends of the upper end plate or the lower end plate. The second energy-dissipating structure is located in the middle of the two groups of the first energy-dissipating structures.

8. The anti-seismic protection structure of the underground chamber in coral reef limestone according to claim 7, characterized in that: The first energy-consuming structure includes an upper connecting steel plate, a lower connecting steel plate, a coupling connecting body, a cylindrical coupling, an axial energy-consuming plate, and an inclined energy-consuming plate. The upper connecting steel plate and the lower connecting steel plate are respectively connected to the upper end plate and the lower end plate. The coupling connecting bodies are arranged on the opposite sides of the upper connecting steel plate and the lower connecting steel plate. At least one axial energy-consuming plate is arranged on each coupling connecting body. The axial energy-consuming plates on one coupling connecting body are connected to the axial energy-consuming plates on the other coupling connecting body through the cylindrical coupling. One end of the inclined energy-consuming plate is connected to the lower connecting steel plate, and the other end abuts against the upper end plate. The inclined energy-consuming plate is inclined towards the second energy-consuming structure.

9. The aseismic protection structure of the underground chamber in coral reef limestone according to claim 7, characterized in that: The second energy-consuming structure includes a middle connecting web, a central vertical energy-consuming plate, a transverse energy-consuming plate, and a cylindrical central rod. The cylindrical central rod is parallel to the upper end plate or the lower end plate. A plurality of transverse energy-consuming plates are arranged at both ends of the cylindrical central rod. Each transverse energy-consuming plate is provided with a central vertical energy-consuming plate. The central vertical energy-consuming plate is perpendicular to the upper end plate or the lower end plate. The central vertical energy-consuming plate is connected to the upper end plate or the lower end plate through the middle connecting web.

10. A construction method of the seismic protection structure for the underground chamber in coral reef limestone as described in any one of claims 1 to 9, characterized in that, It includes the following steps: In the excavated chamber hole, the shotcrete support technology is adopted to spray concrete on the surface of the reef limestone in the chamber hole to form an anchor-shotcrete lining layer; Lay an elastic isolation layer on the surface of the anchor-shotcrete lining layer; Pour concrete on the surface of the elastic isolation layer to form a pouring layer. The pouring layer forms the chamber wall, and the chamber wall includes a bottom layer, side walls, and an arched roof; Among them, before forming the bottom layer, a number of isolation bearings are arranged at intervals in the horizontal direction at the forming position of the bottom layer, and the deviation value between the levelness of the isolation bearing and the inclination of the horizontal plane is not greater than 2%; Before forming the side walls, a number of viscous damping members are arranged at intervals along the extension direction of the chamber hole; When forming the arched roof, a steel arch frame needs to be used for fixation, and a mild steel damper is installed at the top of the arch.

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