Shock absorption structure and method for LNG storage tank

Abstract

The invention discloses an LNG storage tank damping structure which comprises an elevated bearing platform, an LNG concrete storage tank is placed on the top of the elevated bearing platform, a plurality of energy dissipation pile sections are arranged between the bottom of the elevated bearing platform and the ground at intervals, and the energy dissipation pile sections are hinged through energy dissipation tie bars. The ends, away from the elevated bearing platform, of the energy dissipation pile sections are connected with a concrete rigid restraint layer, the concrete rigid restraint layer is arranged on the ground, a plurality of reinforced concrete cast-in-place piles are arranged below the concrete rigid restraint layer, and the reinforced concrete cast-in-place piles and the energy dissipation pile sections are arranged in a one-to-one correspondence mode. The reinforced concrete cast-in-place pile and the multiple energy dissipation pile sections are both bound with the concrete rigid restraint layer, shock absorption is conducted on the LNG concrete storage tank on the elevated bearing platform through the energy dissipation pile sections, the energy dissipation tie bars and the concrete rigid restraint layer, and the invention further discloses an LNG storage tank shock absorption method. According to the damping structure and method for the LNG storage tank, the structural stress of the LNG concrete storage tank is reduced, the cost and difficulty are reduced, and the working efficiency is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of LNG storage tanks, and in particular relates to a shock absorbing structure and method for an LNG storage tank. Background Art

[0002] In the liquefied natural gas (LNG) receiving station industry, large LNG concrete storage tanks in areas with high seismic fortification intensity can achieve seismic isolation effects on the tank body by installing rubber seismic isolation bearings between the elevated pedestal and the pile foundation under earthquake conditions, using the seismic isolation bearings to consume part of the seismic energy.

[0003] Although the seismic isolation bearing can mitigate the destructive effects of earthquake forces on the tank body, its construction cost is relatively high and its production cycle is long. The number of products produced in each batch is limited. At the same time, according to product specifications, a single batch of products needs to be sampled and evaluated before it can be delivered to the site, which increases the procurement cycle. During construction and installation, it is also necessary to configure lifting and positioning equipment and perform pre-embedded secondary grouting operations, which further increases the difficulty of construction and has a greater impact on projects with tight schedule requirements.

[0004] Therefore, it is urgent to design a shock-absorbing structure and method for LNG storage tanks to solve the above-mentioned problems of using seismic isolation bearings for shock absorption, which leads to low efficiency, high cost and great construction difficulty. Summary of the invention

[0005] In order to solve the technical problems mentioned in the background technology of using seismic isolation bearings for shock absorption, which leads to low efficiency, high cost and great construction difficulty, a shock absorption structure and method for an LNG storage tank is provided to solve the above problems.

[0006] To achieve the above objectives, the specific technical solutions of the LNG storage tank shock absorbing structure and method of the present invention are as follows: An LNG storage tank shock-absorbing structure comprises an elevated pedestal, an LNG concrete storage tank is placed on the top of the elevated pedestal, a plurality of energy-absorbing pile segments are arranged at intervals between the bottom of the elevated pedestal and the ground, the plurality of energy-absorbing pile segments are hinged by energy-absorbing tie rods, one end of the plurality of energy-absorbing pile segments away from the elevated pedestal is connected with a concrete rigid constraint layer, the concrete rigid constraint layer is arranged on the ground, a plurality of reinforced concrete cast-in-place piles are arranged below the concrete constraint layer, the reinforced concrete cast-in-place piles are arranged in one-to-one correspondence with the plurality of energy-absorbing pile segments, the reinforced concrete cast-in-place piles and the plurality of energy-absorbing pile segments are all tied to the concrete rigid constraint layer, and the LNG concrete storage tank on the elevated pedestal is shock-absorbing by the energy-absorbing pile segments, the energy-absorbing tie rods and the concrete rigid constraint layer.

[0007] Furthermore, the energy-absorbing tie rod is in a V-shaped structure, one end of the V-shaped structure is connected to an energy-absorbing pile segment, and the other end of the V-shaped structure is connected to another adjacent energy-absorbing pile segment.

[0008] Furthermore, the energy-absorbing pile segments and energy-absorbing tie rods are both composed of ductile concrete and FRP bars.

[0009] Furthermore, a compacted reinforced soil layer is arranged below the concrete constraining layer, and the compacted reinforced soil layer performs rigid constraints on the concrete constraining layer.

[0010] Furthermore, the thickness of the compacted reinforced soil layer is greater than 1500 mm, reinforcement materials are laid every 300 mm in the compacted reinforced soil layer, and the compaction coefficient is greater than 0.95.

[0011] Furthermore, the maximum allowable deformation formula of the energy-absorbing pile segment and the energy-absorbing tie rod is as follows: =0.00542 / 3 in, - the maximum permissible deformation of the energy dissipation pile segment; Q-equivalent uniformly distributed load of horizontal earthquake on energy-absorbing pile section; L-length of energy dissipation pile section; - elastic modulus of ductile concrete; - Section moment of inertia of the energy dissipation pile segment.

[0012] Furthermore, the actual restoring tension and tensile bearing capacity formula of the energy dissipation tie rod are as follows: in, A- cross-sectional area of ​​the energy dissipation tie rod; Fmax-actual restoring tension on the energy-absorbing tie rod; -Tensile bearing capacity of the energy dissipation tie rod; - Design value of tensile bearing capacity of ductile concrete of energy dissipation tie rod; - Design value of tensile bearing capacity of FRP bars of energy dissipation tie rods; -Total reinforcement area of ​​FRP bars of energy dissipation tie rods.

[0013] Furthermore, the ultimate shear strength formula of compacted reinforced soil is as follows: in, -Ultimate shear strength of compacted reinforced soil; - Normal stress on compacted reinforced soil; C- cohesion of compacted reinforced soil; - Friction angle inside compacted reinforced soil.

[0014] A method for reducing shock of an LNG storage tank comprises the following steps: S1. Multiple reinforced concrete piles are set at intervals under the ground; S2, pouring concrete in reinforced concrete piles to form a concrete rigid constraint layer on the ground; S3, tie multiple energy-absorbing pile segment FRP bars on the concrete rigid constraint layer to the elevated cap; S4, pouring toughness concrete of energy-absorbing pile segment to the elevation of the bottom surface of elevated cap to form energy-absorbing pile segment; S5. Tie the energy-absorbing tie rod FRP bars on the sides of the adjacent energy-absorbing pile sections, and pour the energy-absorbing tie rod ductile concrete into the energy-absorbing tie rod FRP bars to form the energy-absorbing tie rod.

[0015] Furthermore, before step S3, it also includes laying a rammed reinforced soil layer under the concrete rigid constraint layer and compacting it.

[0016] The LNG storage tank shock absorption structure and method of the present invention have the following advantages: The energy-absorbing pile segment is rigidly connected to the reinforced concrete cast-in-place pile near the concrete rigid constraint layer elevation, the energy-absorbing tie rod is hinged to the energy-absorbing pile segment at the bottom of the elevated pedestal, and the concrete rigid constraint layer is set at the bottom elevation of the energy-absorbing pile segment and rigidly connected to the energy-absorbing pile segment as the limiting constraint end of the energy-absorbing pile segment. The upper part of the energy-absorbing pile segment is semi-rigidly connected to the elevated pedestal. The energy-absorbing pile segment, the energy-absorbing tie rod, and the concrete rigid constraint layer together form a high-ductility energy-absorbing structural system. Under earthquake conditions, it can withstand displacement deformations that exceed those of conventional concrete material structural systems. Combined with the elastic recovery performance of the energy-absorbing tie rod, the structure can effectively return to its original position after a large deformation and continue to meet the use requirements. During the deformation process, the energy-absorbing structural system can absorb and consume a large part of the seismic force, reduce the seismic effect of the overall structure of the LNG concrete storage tank, reduce the structural stress of the LNG concrete storage tank, reduce costs and construction difficulties, and improve work efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic structural diagram of the LNG storage tank shock absorbing structure of the present invention; Figure 2 It is a partial structural schematic diagram of the shock absorbing structure of the LNG storage tank of the present invention.

[0018] Description of the markings in the figure: 1. LNG concrete storage tank; 2. Elevated pedestal; 3. Energy-absorbing pile segment; 31. FRP reinforcement; 4. Energy-absorbing tie rod; 5. Concrete rigid constraint layer; 6. Compacted reinforced soil layer; 7. Reinforced concrete cast-in-place pile; 8. Reinforcement material. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0020] Those skilled in the art will appreciate that, although some embodiments herein include certain features included in other embodiments but not other features, the combination of features of different embodiments is meant to be within the scope of the present invention and form different embodiments. For example, in the claims, any one of the claimed embodiments may be used in any combination.

[0021] Please refer to the attached Figure 1 To Attachment Figure 2 The LNG storage tank shock absorbing structure and method of the present invention are described.

[0022] like Figure 1 As shown, the LNG storage tank shock-absorbing structure in the present invention includes an elevated cap 2, an LNG concrete storage tank 1 is placed on the top of the elevated cap 2, a plurality of energy-absorbing pile segments 3 are arranged between the bottom of the elevated cap 2 and the ground, the plurality of energy-absorbing pile segments 3 are hinged by energy-absorbing tie rods 4, one end of the plurality of energy-absorbing pile segments 3 away from the elevated cap 2 is connected to a concrete rigid constraint layer 5, the concrete rigid constraint layer 5 is arranged on the ground, a plurality of reinforced concrete cast-in-place piles 7 are arranged below the concrete constraint layer, the reinforced concrete cast-in-place piles 7 are arranged one-to-one with the plurality of energy-absorbing pile segments 3, the reinforced concrete cast-in-place piles 7 and the plurality of energy-absorbing pile segments 3 are all tied with the concrete rigid constraint layer 5, and the LNG concrete storage tank 1 on the elevated cap 2 is shock-absorbing by the energy-absorbing pile segments 3, the energy-absorbing tie rods 4 and the concrete rigid constraint layer 5. In this embodiment, the reinforced concrete cast-in-place piles 7 are conventional concrete cast-in-place piles, and a suitable pile end soil layer is selected according to the estimated vertical load of the storage tank and the geological survey data.

[0023] The energy-absorbing pile segment 3 is rigidly connected to the reinforced concrete cast-in-place pile 7 near the elevation of the concrete rigid constraint layer 5, and the energy-absorbing tie rod 4 is hinged to the energy-absorbing pile segment 3 at the bottom of the elevated pedestal 2. At the same time, the concrete rigid constraint layer 5 is set at the bottom elevation of the energy-absorbing pile segment 3 and rigidly connected to the energy-absorbing pile segment 3 as the limiting constraint end of the energy-absorbing pile segment 3. The upper part of the energy-absorbing pile segment 3 is semi-rigidly connected to the elevated pedestal 2. The energy-absorbing pile segment 3, the energy-absorbing tie rod 4, and the concrete rigid constraint layer 5 together form a high-ductility energy-absorbing structural system. Under earthquake conditions, it can withstand a larger displacement deformation than the conventional concrete material structural system. Combined with the elastic recovery performance of the energy-absorbing tie rod 4, the structure can effectively return to its original position after a large deformation and continue to meet the use requirements. During the deformation process, the energy-absorbing structural system can absorb and consume a large part of the seismic force, reduce the seismic effect of the overall structure of the LNG concrete storage tank 1, reduce the structural stress of the LNG concrete storage tank 1, reduce costs and construction difficulties, and improve work efficiency.

[0024] Further, if Figure 1 and Figure 2 As shown, the energy absorbing tie rod 4 is in a V-shaped structure, one end of the V-shaped structure is connected to one energy absorbing pile segment 3, and the other end of the V-shaped structure is connected to another adjacent energy absorbing pile segment 3. In this embodiment, the energy absorbing pile segment 3 and the energy absorbing tie rod 4 are both composed of tough concrete and FRP bars.

[0025] Further, if Figure 1 and Figure 2 As shown, the concrete rigid constraint layer 5 is a reinforced concrete slab with a thickness of not less than 180 mm, and the concrete rigid constraint layer 5 is rigidly connected to the lower reinforced concrete pile. A compacted reinforced soil layer 6 is arranged below the concrete rigid constraint layer 5, and the compacted reinforced soil layer 6 rigidly constrains the concrete rigid constraint layer 5. The thickness of the compacted reinforced soil layer 6 is greater than 1500 mm, and the compacted reinforced soil layer 6 is laid with reinforcement materials every 300 mm, and the compaction coefficient is greater than 0.95. The compacted reinforced soil layer 6 is a concrete slab, which provides conditions for realizing the rigid constraint effect and also avoids the frost heave effect of the soil on the rigid slab in a low temperature environment.

[0026] The above parts are simulated equivalently using general finite element software. After equivalent connection with the LNG storage tank and elevated pedestal 2, the overall model is created. By solving, the structural internal force results of the LNG storage tank under the elastic energy dissipation foundation form can be obtained. The calculation and simulation methods of the energy dissipation structure are mainly: According to the principles of soil mechanics and the contents of the engineering investigation report, after obtaining the equivalent spring stiffness coefficients of the three directions of XYZ of each layer of soil, the equivalent spring pile-soil coupling method is adopted to connect the equivalent spring models in the three directions at the nodes at the midpoints of each unit segment of the reinforced concrete pile 7 to simulate the force of the soil layer on the reinforced concrete pile 7; Pick up the top grid node of the energy-absorbing pile segment 3 and constrain it with the corresponding area on the lower surface of the elevated cap 2. At the same time, constrain the bottom grid node of the energy-absorbing pile segment 3 and the reinforced concrete cast-in-place pile 7 at the top elevation of the rigid constraint layer to establish a degree of freedom coupling relationship and achieve coordinated deformation; Pick up the middle node of the energy-absorbing pile segment 3, constrain it with the end node of the energy-absorbing tie rod 4, establish a degree of freedom coupling relationship, and achieve coordinated deformation; After the LNG concrete storage tank 1 and the elevated pedestal 2 are fitted with the energy-dissipating structure system, the overall calculation is performed according to the three-dimensional finite element analysis method of conventional LNG storage tanks under various load combination conditions, and the structural detail optimization design is performed according to the stress results.

[0027] Further, if Figure 1 and Figure 2 As shown in the figure, assuming that the elastic modulus of ductile concrete is Ea, according to the deformation theory of structural mechanics, the energy dissipation pile segment 3 is fixedly constrained by the concrete rigid constraint layer 5 at one end and simply supported by the elevated cap 2 at the other end. The energy dissipation tie rod 4 is arranged on the side of the energy dissipation pile segment 3 to transmit the axial force and provide the restoring force. The ductility capacity of the energy dissipation structure includes the following formula: The maximum allowable deformation formula of the energy-absorbing pile segment 3 and the energy-absorbing tie rod 4 is as follows: =0.00542 / 3 in, - The maximum permissible deformation of the energy-absorbing pile segment 3 is based on the uncertainty of the position where the seismic force acts, and the theoretical maximum displacement formula is used as the deformation value at each elevation of the energy-absorbing pile segment 3 and the tensile deformation value of the corresponding energy-absorbing tie rod 4; Q-equivalent uniformly distributed horizontal earthquake load of energy-absorbing pile segment 3; L- the length of the energy-absorbing pile section 3, from the top elevation of the concrete rigid constraint layer 5 to the bottom elevation of the elevated cap 2; - elastic modulus of ductile concrete; - Sectional moment of inertia of the energy dissipation pile segment 3.

[0028] In the process of mixing tough concrete, rubber or particles of materials with similar properties are used as cement admixtures and mixed with aggregates, cement, etc. to make its performance between rigid concrete and flexible concrete. The added particles are used to greatly improve the ductility of concrete. When subjected to a huge impact, it presents an elastic bending state instead of brittle fracture. The tough concrete used combines the characteristics of rubber and cement concrete. Compared with conventional concrete, it has excellent crack resistance, energy absorption capacity increased by more than 25%, high toughness, and deformation capacity far higher than the ultimate deformation capacity of conventional concrete (0.6% ultimate deformation). The elastic modulus Ea can be 1 / 4 of that of conventional concrete or even lower according to different needs. It can be concluded from the above formula that the smaller Ea is, the greater the deformation value allowed to occur, and the allowable value can exceed that of conventional concrete by more than four times, so that the structure has high-strength ductility and is suitable for large deformation stress conditions of LNG storage tanks.

[0029] The mechanical properties of the FRP bar 31 used match the structural system with high ductility requirements. According to theoretical calculations and experimental data analysis, the deflection relationship curve of the FRP concrete beam model is a straight line before the section cracks. After cracking, due to the reduction in stiffness, a short horizontal line segment appears, and the load-deflection curve shows a more obvious linear feature, which is consistent with the linear elastic mechanical properties.

[0030] From the analysis of the typical FRP concrete component destruction test results, under the action of external load, the expansion of concrete cracks mainly occurs at the FRP material interface, indicating that the mechanical properties of FRP bar 31 material can well prevent concrete cracking. In addition, according to the corrosion experiment, its corrosion resistance is much greater than that of ordinary normal temperature or low temperature steel bars. According to the normal use limit state theory, the crack requirements for concrete components can be relaxed. Compared with the 0.3mm calculated crack limit value of conventional concrete durability specifications, referring to "CJJT280-2018 Technical Standard for Fiber Reinforced Composite Material Reinforced Concrete Bridges", FRP bar 31 concrete can allow a crack width of 0.5mm, which improves the upper limit of the structural applicability bearing capacity and makes full use of the ductile recovery capacity of the structural system.

[0031] Further, if Figure 1 and Figure 2 As shown, the actual restoring tension and tensile bearing capacity formula of the energy dissipation tie rod 4 are as follows: in, A- cross-sectional area of ​​the energy dissipation tie rod 4; Fmax-actual restoring tension of the energy-absorbing tie rod 4; - The tensile bearing capacity of the energy dissipation tie rod 4; - Design value of the tensile bearing capacity of the ductile concrete of the energy dissipation tie rod 4; - Design value of tensile bearing capacity of FRP bars of energy dissipation tie rod 4; -The total reinforcement area of ​​FRP bars of energy dissipation tie rod 4.

[0032] The actual restoring tension and bearing capacity of the energy-absorbing tie rod 4 can be calculated according to the above formula. When the calculated result Fmax≤ When , it meets the design requirements. If the above results are not met, it is necessary to adjust the dimensions of each section until they are met. The parameters on the right side of the above equation are all known, among which the horizontal seismic equivalent uniformly distributed load Q is the equivalent seismic load design value given by the distribution of seismic action after the overall finite element analysis of the tank.

[0033] Further, if Figure 1 and Figure 2 As shown in Figure 2, the ultimate shear strength formula of compacted reinforced soil is as follows: in, -Ultimate shear strength of compacted reinforced soil; - Normal stress on compacted reinforced soil; C- cohesion of compacted reinforced soil; - Friction angle inside compacted reinforced soil.

[0034] Reinforced material 8 is a synthetic material used in geotechnical engineering to increase the stability of geotechnical engineering or improve the bearing capacity. Commonly used reinforced materials 8 include geogrids, woven geotextiles and reinforced tapes. The reinforced material and the soil form a reinforced body. Each layer of reinforced material 8 and the fill is regarded as a "laminar unit". The entire reinforced body is composed of a finite layer of laminate units bonded together. Assuming that each layer unit has a unique and definite material property, the incremental analysis method can be used to calculate the displacement and stress of the laminate unit in the elastic-plastic state, thereby analyzing the stress-deformation characteristics of the reinforced body. In the above formula, since the reinforcing material 8 and the soil are combined with each other and the deformation is coordinated, the cohesion C of the compacted reinforced soil and the friction angle of the compacted reinforced soil are Compared with conventional soil, the ultimate shear strength of compacted reinforced soil is improved. The corresponding improvement will increase the horizontal ductility of the structure and achieve the purpose of shock reduction and energy consumption.

[0035] The present invention also discloses a LNG storage tank shock reduction method, comprising the following steps: S1, multiple reinforced concrete piles 7 are arranged at intervals under the ground, and reinforcing materials 8 are arranged between two adjacent reinforced concrete piles 7; S2, pouring concrete in the reinforced concrete pile 7 to the concrete rigid constraint layer 5 on the ground; S3, breaking the pile head, flowing out of the energy-absorbing pile segment 3 binding overlap space, binding multiple FRP bars 31 of the energy-absorbing pile segment 3 on the concrete rigid constraint layer 5 to the elevated cap 2; S4. Overlap and tie the FRP steel bars with the ordinary steel bars within the length range from the top of the poured reinforced concrete pile 7 to the anchorage length of the lower ordinary steel bars. Due to the setting of the concrete rigid constraint layer 5, the overlap does not need to consider the staggered requirements. The number of FRP bars 31 is set according to the estimated bearing capacity limit load and the normal use limit load. Pour the ductile concrete of the energy-absorbing pile segment 3 to the bottom elevation of the concrete rigid constraint layer 5 to form the energy-absorbing pile segment 3; 5. Set a 1500mm thick medium-coarse sand cushion layer 6 within the horizontal projection range of the elevated cap 2 and compact it, and lay reinforcement materials every 300mm, with a compaction coefficient of not less than 0.95; S5. Tie the FRP bars of the energy absorbing tie rod 4 to the sides of the adjacent energy absorbing pile segments 3, and pour tough concrete of the energy absorbing tie rod 4 into the FRP bars of the energy absorbing tie rod 4 to form the energy absorbing tie rod 4.

[0036] The steel bars of the concrete rigid constraint layer 5 and the steel bars of the reinforced concrete bored piles 7 are horizontally tied together. First, conventional concrete is poured to the top elevation of the concrete rigid constraint layer 5. After the constraint layer concrete reaches the design strength, the FRP bars are continued to be tied to the elevation that meets the anchorage length of the ordinary steel bars of the elevated pedestal 2. At the same time, the FRP bar binding joints of the energy-absorbing tie rods 4 are reserved.

[0037] Pour tough concrete to 100mm above the bottom elevation of the elevated pedestal 2 to form an energy-absorbing pile section 3. After the energy-absorbing pile section 3 reaches the design strength, tie the FRP bars of the energy-absorbing tie rod 4 at the reserved binding joints. To improve the elastic capacity of the energy-absorbing tie rod 4, set it as a V-shaped energy-absorbing tie rod 4. After pouring tough concrete for the energy-absorbing tie rod 4, a high-ductility energy-absorbing structural system is finally formed.

[0038] Further, if Figure 1 and Figure 2 As shown, before step S3, it also includes laying a rammed reinforced soil layer 6 under the concrete rigid constraint layer 5 and compacting it.

[0039] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A shock absorbing structure for an LNG storage tank, characterized in that: It includes an elevated pedestal, an LNG concrete storage tank is placed on the top of the elevated pedestal, a plurality of energy-absorbing pile segments are arranged between the bottom of the elevated pedestal and the ground, the plurality of energy-absorbing pile segments are hinged by energy-absorbing tie rods, one end of the plurality of energy-absorbing pile segments away from the elevated pedestal is connected with a concrete rigid constraint layer, the concrete rigid constraint layer is arranged on the ground, a plurality of reinforced concrete cast-in-place piles are arranged under the concrete constraint layer, the reinforced concrete cast-in-place piles are arranged in one-to-one correspondence with the plurality of energy-absorbing pile segments, the reinforced concrete cast-in-place piles and the plurality of energy-absorbing pile segments are all tied to the concrete rigid constraint layer, and the LNG concrete storage tank on the elevated pedestal is shock-absorbed by the energy-absorbing pile segments, the energy-absorbing tie rods and the concrete rigid constraint layer.

2. The shock absorbing structure of the LNG storage tank according to claim 1 is characterized in that: The energy-absorbing tie rod is in a V-shaped structure, one end of the V-shaped structure is connected to an energy-absorbing pile segment, and the other end of the V-shaped structure is connected to another adjacent energy-absorbing pile segment.

3. The shock absorbing structure of the LNG storage tank according to claim 1, characterized in that: The energy-absorbing pile segments and energy-absorbing tie rods are both composed of ductile concrete and FRP bars.

4. The shock absorbing structure of the LNG storage tank according to claim 1, characterized in that: A compacted reinforced soil layer is arranged below the concrete constraining layer, and the compacted reinforced soil layer performs rigid constraints on the concrete constraining layer.

5. The shock absorbing structure of the LNG storage tank according to claim 4 is characterized in that: The thickness of the compacted reinforced soil layer is greater than 1500mm, and reinforcing materials are laid every 300mm in the compacted reinforced soil layer. The compaction coefficient is greater than 0.

95.

6. The shock absorbing structure of the LNG storage tank according to claim 1, characterized in that: The maximum allowable deformation formula of the energy-absorbing pile segment and the energy-absorbing tie rod is as follows: / 3 in, - the maximum permissible deformation of the energy dissipation pile segment; Q-equivalent uniformly distributed load of horizontal earthquake on energy-absorbing pile section; L-length of energy dissipation pile section; - elastic modulus of ductile concrete; - Section moment of inertia of the energy dissipation pile segment.

7. The shock absorbing structure of the LNG storage tank according to claim 6, characterized in that: The actual restoring tension and tensile bearing capacity formula of the energy dissipation tie rod are as follows: in, A- cross-sectional area of ​​the energy dissipation tie rod; Fmax-actual restoring tension on the energy-absorbing tie rod; -Tensile bearing capacity of the energy dissipation tie rod; - Design value of tensile bearing capacity of ductile concrete of energy dissipation tie rod; - Design value of tensile bearing capacity of FRP bars of energy dissipation tie rods; -Total reinforcement area of ​​FRP bars of energy dissipation tie rods.

8. The shock absorbing structure of the LNG storage tank according to claim 7, characterized in that: The ultimate shear strength formula of compacted reinforced soil is as follows: in, -Ultimate shear strength of compacted reinforced soil; - Normal stress on compacted reinforced soil; C- cohesion of compacted reinforced soil; - Friction angle inside compacted reinforced soil.

9. A method for reducing shock of an LNG storage tank, characterized in that: The following steps are involved: S1. Multiple reinforced concrete piles are set at intervals under the ground; S2, pouring concrete in reinforced concrete piles to form a concrete rigid constraint layer on the ground; S3, tying FRP bars of multiple energy-absorbing pile segments to the elevated cap on the concrete rigid constraint layer; S4, pouring toughness concrete of energy-absorbing pile segment to the elevation of the bottom surface of elevated cap to form energy-absorbing pile segment; S5. The FRP bars of the energy absorbing tie rod are tied to the sides of the adjacent energy absorbing pile sections, and the tough concrete of the energy absorbing tie rod is poured into the FRP bars of the energy absorbing tie rod to form the energy absorbing tie rod.

10. The LNG storage tank shock reduction method according to claim 9, characterized in that: Before step S3, it also includes laying a rammed reinforced soil layer under the concrete rigid constraint layer and compacting it.

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