Thin cushion layer seismic isolation foundation of nuclear power station in high-intensity area and construction method

Abstract

The invention discloses a thin cushion layer seismic isolation foundation of a nuclear power plant in a high-intensity area and a construction method. The shock insulation foundation comprises a nuclear power station plant bottom plate and a nuclear power station plant outer wall, and a plurality of grouting holes are reserved in the nuclear power station plant bottom plate; a foundation pit sealing bottom is arranged below a bottom plate of the nuclear power plant, and a pile group foundation is arranged below the foundation pit sealing bottom. A single-layer pebble cushion layer is arranged between the bottom plate of the nuclear power plant and the foundation pit sealing bottom A shallow diaphragm wall is arranged below the ground outside the nuclear power plant outer wall; and a tire buffer layer is arranged between the nuclear power plant outer wall and the shallow diaphragm wall. The single-layer pebble cushion layer is laid, so that cushion layer particles roll under the action of a strong earthquake, further upward conduction of the earthquake action is isolated, and the dynamic response of a nuclear power plant and a reactor plant is remarkably reduced; point-shaped grouting is arranged in partial area of the cushion layer, semi-rigid connection between the plant bottom plate and the foundation pit sealing bottom is formed, the shock isolation pebble cushion layer gives full play to the shock isolation effect, and meanwhile the tire buffering layer provides displacement restoring force.

Description

Technical Field

[0001] The invention relates to a building seismic isolation foundation and a construction method, in particular to a thin cushion layer seismic isolation foundation and a construction method for a nuclear power plant in a high-intensity area. Background Art

[0002] In some areas with frequent seismic activity, conventional energy sources such as hydropower and thermal power are limited by the terrain and environment and cannot meet the growing demand for electricity. Nuclear power plants have become an important energy option in these areas due to their high efficiency, low carbon and sustainability. High-intensity areas are usually located in areas with frequent seismic activity, such as near earthquake fault zones. The seismic intensity in these areas is high, which places extremely high demands on the seismic resistance of building structures, especially critical infrastructure such as nuclear power plants. With the development of engineering seismic resistance technology, it is now possible to design and build nuclear power plants that can withstand extreme seismic events in high-intensity areas. For example, the use of seismic isolation technology, energy absorption devices and high-performance materials can greatly improve the seismic resistance of nuclear power plants.

[0003] However, as a foundation for nuclear power plants in high-intensity areas that needs to be further developed, the existing seismic isolation foundation still has some urgent problems to be solved in terms of seismic isolation effect and reset capacity. First, under strong earthquake conditions, the seismic isolation performance of the existing foundation is not outstanding. In the environment that is most conducive to the seismic isolation performance, the foundation isolation rate is still less than 30%, which still has great potential for improvement compared with the 40% to 80% isolation rate of the traditional upper structure lead rubber bearing. Secondly, the cushion thickness of the existing seismic isolation foundation of nuclear power plants in high-intensity areas is about 2.0m to 4.0m. Under dynamic action, the cushion may produce unacceptable vertical compression deformation, or even a certain degree of differential settlement, which will cause the upper structure to tilt and affect the structural safety. Finally, the existing seismic isolation foundation of nuclear power plants in high-intensity areas has the problems of poor seismic toughness, high cost of setting reset facilities, and inability to fully recover the horizontal displacement after the earthquake, which is not conducive to the safe use of the structure after the earthquake. Under small earthquake conditions, the existing seismic isolation foundation of nuclear power plants in high-intensity areas with good seismic isolation performance has the problem of excessive displacement response of the upper structure, which may have a great impact on the normal use of nuclear power plants.

[0004] In the face of the above problems, it is necessary to design a thin-layer seismic isolation foundation for a nuclear power plant with a high seismic isolation rate and good seismic toughness to solve the above problems. Summary of the invention

[0005] Purpose of the invention: The purpose of the present invention is to provide a thin cushion isolation foundation for nuclear power plants in high-intensity areas, which has a high isolation rate, small cushion settlement, and good seismic toughness;

[0006] The second object of the present invention is to provide a construction method for the above-mentioned thin cushion isolation foundation of a nuclear power plant in a high-intensity area.

[0007] Technical solution: The thin cushion isolation foundation of a nuclear power plant in a high-intensity area described in the present invention comprises a nuclear power plant building floor plate and an outer wall of the nuclear power plant building fixed on the nuclear power plant building floor plate, wherein the nuclear power plant building floor plate is provided with a plurality of grouting holes; a foundation pit bottom is provided below the nuclear power plant building floor plate, and a pile group foundation is provided below the foundation pit bottom plate; a single-layer pebble cushion is provided between the nuclear power plant building floor plate and the foundation pit bottom plate, and the grouting holes are connected to the single-layer pebble cushion layer for allowing slurry to enter the single-layer pebble cushion layer for bonding the pebble particles; a shallow ground connection wall is provided below the ground outside the outer wall of the nuclear power plant building; a tire buffer layer for limiting the horizontal displacement of the nuclear power plant is provided between the outer wall of the nuclear power plant building and the shallow ground connection wall.

[0008] Wherein, a detachable displacement recovery device is arranged between the shallow buried connecting wall and the outer wall of the nuclear power plant building.

[0009] Among them, the layout of grouting holes needs to take into account the center and peripheral areas of the bottom plate and be symmetrically distributed to provide sufficient anti-torsion torque and uniform shear resistance; the grouting holes are arranged in the central area and peripheral areas of the nuclear power plant floor; the spacing between grouting holes in the central area is 0.05 to 0.1 times the long side length of the nuclear power plant floor according to the need for shear resistance, and the spacing between grouting holes in the peripheral area is 0.05 to 0.2 times the long side length of the nuclear power plant floor.

[0010] The grouting holes are arranged in a dotted pattern; the cement mortar filled between the single-layer pebble cushion layers through the dotted grouting holes effectively improves the horizontal bearing capacity of the single-layer pebble cushion layer and reduces the displacement response of the structure under small earthquakes and normal use loads. The cement mortar filled between the cushion particles will have two effects. One is to directly bond the floor slab of the nuclear power plant building and the bottom of the foundation pit, making them connected as a whole without dislocation; the other is to wrap and bond multiple pebbles, changing their own rounded geometric shape and making them difficult to roll. The above two effects can significantly improve the horizontal bearing capacity and stiffness of the foundation. The grouting area under each grouting hole is not less than 0.78m 2 , at least 5 cushion particles are bonded; the grouting holes can be arranged in multiple batches.

[0011] Wherein, the tire buffer layer is filled with cut and processed waste tire blocks.

[0012] Wherein, the particle size of the pebbles in the single-layer pebble cushion is 25cm to 40cm.

[0013] Among them, the filling height of the tire buffer layer is 1 / 4 to 1 / 2 of the buried depth of the nuclear power plant building floor.

[0014] Among them, the horizontal gap between the outer side of the nuclear power plant building wall and the inner side of the shallow ground-connected wall ranges from 0.5m to 3.0m.

[0015] The detachable displacement recovery device includes a plurality of detachable actuators and an electronic control system. The detachable actuators are arranged between the shallow ground-connected wall and the outer wall of the nuclear power plant and above the tire buffer layer. The height of the detachable actuators is the same as the height of the internal floor of the nuclear power plant, forming a synchronous jacking group. After the jacking is completed, the displacement recovery device can be detached and stored.

[0016] The above-mentioned construction method of the thin cushion isolation foundation of a nuclear power plant in a high-intensity area comprises the following steps:

[0017] (A1) Clean and level the construction site, dig a slot, prefabricate a shallow ground-connected wall steel cage on the ground, place it into the slot using a lifting device, pour concrete to form a shallow ground-connected wall, and then excavate the soil inside the wall. After excavating to the designed elevation, use a pile driver to complete the construction of the pile group foundation from the inside out one by one;

[0018] (B1) Cast reinforced concrete bottom seal on the bottom surface of the foundation pit, lay a single layer of pebble cushion on the bottom seal after it is leveled and has formed strength, prefabricate the nuclear power plant building floor, and reserve multiple grouting holes, and grouting the multiple grouting holes in batches; use lifting equipment to place the prefabricated nuclear power plant building floor on the pebble cushion, complete the grouting of the first batch of grouting holes, and grouting the remaining batches of grouting holes as needed;

[0019] (C1) Tie up the steel bars for the outer wall of the nuclear power plant, install the wall formwork, pour concrete, complete the outer wall of the nuclear power plant, and then continue the construction of other structures and equipment of the nuclear power plant;

[0020] (D1) The cut waste tire blocks are filled between the shallow ground connection wall and the outer wall of the nuclear power plant building to form a tire buffer layer.

[0021] The above-mentioned construction method of the thin cushion isolation foundation of a nuclear power plant in a high-intensity area comprises the following steps:

[0022] (A2) Clean and level the construction site, dig a slot, prefabricate a shallow ground-connected wall steel cage on the ground, place it into the slot using a lifting device, pour concrete to form a shallow ground-connected wall, and then excavate the soil inside the wall. After excavating to the designed elevation, use a pile driver to complete the construction of the pile group foundation from the inside out one by one;

[0023] (B2) Casting reinforced concrete bottom seal on the bottom surface of the foundation pit, laying a single layer of pebble cushion on the bottom seal after it is leveled and has formed strength, prefabricating the nuclear power plant building floor, and reserving multiple grouting holes, and grouting the multiple grouting holes in batches; using lifting equipment to place the prefabricated nuclear power plant building floor on the pebble cushion, grouting the first batch of grouting holes, and grouting the remaining batches of grouting holes as needed;

[0024] (C2) Tie up the steel bars for the outer wall of the nuclear power plant, install the wall formwork, pour concrete, complete the outer wall of the nuclear power plant, and then continue the construction of other structures and equipment of the nuclear power plant;

[0025] (D2) Filling the cut waste tire blocks between the shallow ground connection wall and the outer wall of the nuclear power plant building to form a tire buffer layer;

[0026] (E2) A detachable displacement recovery device is installed on the outer wall of the nuclear power plant building outside the internal floor slab to recover the irreversible horizontal displacement after the earthquake, and a batch of grouting holes is grouted to restore the horizontal stiffness of the foundation.

[0027] Beneficial effects: Compared with the prior art, the present invention achieves the following significant effects:

[0028] (1) The present invention lays a single-layer pebble cushion between the nuclear power plant building floor and the bottom of the shallow ground-connected wall foundation pit, so that under the action of a strong earthquake, the cushion particles can roll, thereby isolating the seismic action from further transmitting upward, which can significantly reduce the dynamic response of the nuclear power plant building and the reactor building. Secondly, point grouting is carried out in some areas of the cushion to form a semi-rigid connection between the nuclear power plant building floor and the bottom of the foundation pit, so that under the action of a small earthquake, the overall structural stiffness is relatively large. Under the action of a large earthquake, the point connection is sheared and damaged, and the seismic isolation pebble cushion can fully exert its seismic isolation effect. At the same time, a tire buffer layer is arranged between the outer wall of the nuclear power plant building and the outer wall of the shallow ground-connected wall to provide horizontal displacement recovery force.

[0029] (2) When the residual displacement after an earthquake is large, a detachable displacement recovery device can be installed on the outer wall of the nuclear power plant building to quickly restore the structural deformation, so that the seismic isolation foundation has sufficient seismic toughness.

[0030] (3) Good seismic isolation effect: Under the action of a strong earthquake, the pebble particles in the cushion layer roll between the two hard layers of the nuclear power plant building floor and the foundation pit bottom. Since there is only one layer of particles and the two upper and lower hard layers are displaced from each other, the rolling resistance of the cushion particles is very small. Compared with the seismic isolation principle in the prior art that mainly relies on the dislocation of thick cushion particles, the present invention can isolate most of the horizontal seismic force from propagating upward, thereby significantly improving the seismic isolation effect;

[0031] (4) Small cushion layer compression deformation: Since the cushion layer is only arranged with one layer of particles, the cushion layer thickness is extremely small compared with the prior art. Therefore, if the particle crushing is not considered, the cushion layer will hardly undergo compression deformation. Even if the particle crushing is considered, the vertical compression of the cushion layer is negligible, and no differential settlement will occur. Therefore, the problem of large cushion layer deformation in the prior art is overcome;

[0032] (5) Convenient post-earthquake maintenance: Grouting in the reserved grouting holes can effectively improve the horizontal bearing capacity of the pebble cushion layer and reduce the displacement response of the structure to small earthquakes. At the same time, multiple batches of grouting holes are set on the floor of the nuclear power plant building. If the previous grouting area is damaged during a major earthquake, the foundation structure can be repaired multiple times through grouting to restore the horizontal bearing capacity.

[0033] (6) Good seismic toughness: By cutting and processing discarded tires and filling them between the outer wall of the nuclear power plant building and the shallow ground-connected wall, a tire buffer layer is set up to improve the horizontal displacement recovery capacity of the structure under earthquake action and reduce the displacement response of the structure. If necessary, a detachable displacement recovery device can be set on the outer wall of the rectangular podium floor after the earthquake to restore the residual displacement.

[0034] (7) Low cost of seismic isolation measures: Using pebbles and discarded tires as materials for seismic isolation foundations effectively reduces the cost of seismic isolation measures compared to traditional seismic isolation bearings, and recycling waste materials is beneficial to environmental protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a schematic diagram of the three-dimensional structure of the present invention;

[0036] Figure 2 It is a front schematic diagram of the structure of the present invention;

[0037] Figure 3 It is a three-dimensional exploded diagram of the present invention;

[0038] Figure 4 It is a top view schematic diagram of the pile group foundation and grouting hole arrangement of the present invention;

[0039] Figure 5 It is a cross-sectional schematic diagram of the pebble interlayer of the present invention;

[0040] Figure 6 It is a side schematic diagram of the arrangement of the detachable displacement recovery device of the present invention;

[0041] Figure 7 It is a schematic diagram of the tire blocks in the tire buffer layer of the present invention. DETAILED DESCRIPTION

[0042] The present invention is described in further detail below.

[0043] See also Figures 1 to 7 The present invention discloses a thin cushion isolation foundation for a nuclear power plant in a high-intensity area, comprising a nuclear power plant building floor 1, a nuclear power plant building outer wall 2, a single-layer pebble cushion 3, a tire buffer layer 4, a shallow ground-connected wall 5, a foundation pit bottom 6, a pile group foundation 7 and a detachable displacement recovery device 8.

[0044] A plurality of groups of point-shaped grouting holes 101 are reserved in the nuclear power plant building floor 1, and the outer side of the nuclear power plant building floor 1 is fixedly connected to the nuclear power plant building outer wall 2. A foundation pit bottom 6 is arranged below the nuclear power plant building floor 1, and a pile group foundation 7 is arranged below the foundation pit bottom 6; a single-layer pebble cushion 3 is arranged between the nuclear power plant building floor 1 and the foundation pit bottom 6, and the single-layer pebble cushion 3 is composed of a single layer of pebbles, and the grouting holes 101 are communicated with the single-layer pebble cushion 3 to allow slurry to enter the single-layer pebble cushion so as to be used to bond the pebble particles; a shallow ground connection wall 5 is arranged below the ground outside the nuclear power plant building outer wall 2; a tire buffer layer 4 for limiting the horizontal displacement of the nuclear power plant is arranged between the nuclear power plant building outer wall 2 and the shallow ground connection wall 5, and the tire buffer layer 4 is composed of cut and processed waste tire blocks.

[0045] The layout of multiple groups of point grouting holes 101 needs to take into account the center and surrounding areas of the base plate and be symmetrically distributed to provide sufficient anti-torsion torque and uniform shear resistance; the grouting holes are arranged in the central area and surrounding areas of the nuclear power plant building base plate; the spacing between the grouting holes in the central area is 0.05 to 0.1 times the length of the long side of the nuclear power plant building base plate according to the need for shear resistance, and the spacing between the grouting holes in the peripheral area is 0.05 to 0.2 times the length of the long side of the nuclear power plant building base plate. The diameter of each grouting hole 101 is 3.5cm to 5.0cm. Multiple groups of point grouting holes are grouted in batches, and each batch is filled with at least 10 grouting holes 101. For specific batches, please refer to Figure 4 In the figure, there are 4 batches of grouting holes, among which A, B, C, and D represent one batch respectively. The structure of the present invention can withstand at least 4 major earthquakes. When pouring the floor 1 of the nuclear power plant building, the PVC pipe is pre-buried, the single hole grouting volume is not less than 0.12 cubic meters, the equivalent filling diameter is not less than 1m, the concrete slurry grade is not less than C30, the slump is 60mm~90mm, and the initial setting time is 20min~40min. The outer wall 2 of the nuclear power plant building is a rectangular frame, and the structural part is shallowly buried in the soil, which is made of reinforced concrete material.

[0046] The single-layer pebble cushion 3 is laid between the nuclear power plant building floor 1 and the foundation pit bottom 6, and only a single layer of large-size pebble particles is evenly arranged, that is, the cushion thickness is equal to the maximum particle size, and the particle size distribution is concentrated, and the pebble particle size is between 25cm and 40cm. The pebble particles are sandwiched between two hard layers that can be regarded as rigid bodies, that is, between the nuclear power plant building floor 1 and the foundation pit bottom 6, so that the rolling resistance of the particles is small. Therefore, when an earthquake occurs, the cushion particles can isolate the seismic effect transmitted from the underground by rolling displacement, and give full play to the seismic isolation effect. At the same time, the cement mortar filled between the single-layer pebble cushion 3 through the point grouting holes 101 effectively improves the horizontal bearing capacity of the single-layer pebble cushion 3, and reduces the displacement response of the structure under small earthquakes and normal use loads. The cement mortar filled between the cushion particles will have two effects. First, it directly bonds the plant floor 1 and the foundation pit bottom 6, making them connected as a whole without displacement; second, it wraps and bonds multiple pebbles, changing their round geometric shape and making them difficult to roll. Both of the above effects can significantly improve the horizontal bearing capacity and rigidity of the foundation. The grouting area under each grouting hole is not less than 0.78m 2 , at least 5 cushion particles are bonded, and the grouting holes can be Figure 4 Multiple batches are shown.

[0047] The tire buffer layer 4 is arranged between the outer wall 2 of the nuclear power plant and the shallow ground-connected wall 5. The gap between the two walls is 0.5m to 3m. It is filled with cut and processed waste tire blocks. The buffer layer is filled as evenly and densely as possible. The filling height is 1 / 4 to 1 / 2 of the buried depth of the plant. The tire buffer layer 4 improves the horizontal displacement recovery force of the structure under earthquake action and reduces the displacement response of the structure.

[0048] In order to solve the irreversible horizontal displacement after the earthquake, a detachable displacement recovery device 8 is set at the position of the outer wall 2 of the nuclear power plant building at the rectangular podium floor after the earthquake to restore the horizontal displacement so that the structure can be quickly restored to use after the earthquake. Figure 6 As shown, the detachable displacement recovery device includes a plurality of detachable actuators 801 and an electronic control system 802. The detachable actuators are arranged between the shallow ground connection wall and the outer wall of the nuclear power plant and above the tire buffer layer. The height of the detachable actuators 801 is the same as the height of the internal floor of the nuclear power plant, forming a synchronous jacking group. After the jacking is completed, the displacement recovery device can be detached and stored.

[0049] The shallow ground-connected wall 5 is arranged outside the outer wall 2 of the nuclear power plant building and is a reinforced concrete structure. The thickness of the foundation pit bottom 6 is not less than 1m, and the pile group foundation 7 is arranged in a square shape under the foundation pit bottom 6. The pile group foundation 7 can use steel pipe piles, concrete mixing piles, precast piles or other suitable pile types.

[0050] The present invention also provides a construction method for a thin cushion isolation foundation of a nuclear power plant in a high-intensity area, comprising the following steps:

[0051] A. Clean and level the construction site, dig a slot, prefabricate a shallow ground-connected wall 5 steel cage on the ground, and place it into the slot with a lifting device. After pouring concrete to form a shallow ground-connected wall 5, excavate the soil inside the wall. After excavating to the designed elevation, use a pile driver to complete the construction of the pile group foundation 7 from the inside out one by one;

[0052] B. Cast reinforced concrete bottom cover 6 on the bottom surface of the foundation pit, lay a single-layer pebble cushion 3 on the bottom cover after it is leveled and has formed strength, prefabricate the nuclear power plant building floor 1 on the ground, and reserve multiple batches of grouting holes 101, use lifting equipment to place the prefabricated floor on the single-layer pebble cushion 3, and complete grouting of the first batch of grouting holes 101;

[0053] C. Tie up the steel bars for the outer wall 2 of the nuclear power plant, install the wall formwork, pour concrete, complete the outer wall 2 of the nuclear power plant, and then continue the construction of other structures and equipment of the nuclear power plant;

[0054] D. Fill the symmetrically cut waste tire blocks between the shallow ground connection wall 5 and the outer wall 2 of the nuclear power plant building to form a tire buffer layer 4.

[0055] If there is irreversible horizontal displacement after the earthquake, a detachable displacement recovery device 8 can be set at the position of the nuclear power plant building outer wall 2 outside the internal floor of the nuclear power plant building to restore the displacement, and complete a batch of grouting holes 101 grouting to restore the horizontal stiffness of the foundation.

[0056] Working principle: The thin cushion isolation foundation of a nuclear power plant in a high-intensity area mainly includes three functions. First, the present invention meets the requirements of the nuclear power plant for foundation bearing capacity and deformation stiffness under the limit state of normal use; secondly, the thin cushion foundation involved in the present invention has only a single layer of cushion particles, and the particles can roll under the action of a strong earthquake, with extremely small resistance, so most of the horizontal seismic forces can be isolated, showing a good isolation effect; finally, the present invention has good seismic toughness and can quickly restore the residual deformation of the structure after a major earthquake.

[0057] In order to meet the first function mentioned above, a thin cushion isolation foundation is provided with a pile group foundation 7 below the foundation pit bottom 6. Combined with the large cross-sectional area of ​​the foundation pit bottom 6 itself, the foundation can easily meet the use requirements in terms of vertical bearing capacity and deformation stiffness. In the horizontal direction, the isolation foundation requires that the foundation should have sufficient horizontal bearing capacity and horizontal stiffness under daily use and small earthquake conditions, and that the horizontal stiffness should be small enough under large earthquake conditions to fully exert the isolation effect. Therefore, a single-layer large-grained pebble cushion is arranged, and the horizontal stiffness of the cushion has a good isolation effect. At the same time, point grouting of the cushion is arranged to bond part of the cushion, so that the cushion has sufficient horizontal stiffness and bearing capacity under daily use and small earthquake conditions. Under large earthquake conditions, the grouting point is destroyed by excessive seismic action and loses its horizontal constraint effect, so that the horizontal stiffness of the cushion foundation drops sharply, so that the isolation effect can be fully exerted. After the earthquake, the cushion can be bonded again through the reserved grouting holes to restore the horizontal resistance of the foundation.

[0058] In order to meet the second function mentioned above, the thin-layer seismic isolation foundation sets a cushion layer with only a single layer of pebble particles between the nuclear power plant building floor 1 and the foundation pit bottom 6. In the structure that is mostly rigidly connected from top to bottom, a layer of "artificial weak surface" is actively set up so that the cushion layer can fully deform under the action of an earthquake, isolating the adverse effects of the earthquake and protecting all structures above the cushion layer. In order to achieve this goal, the pebble particles in the single-layer pebble cushion layer 3 have a larger particle size, and the contact areas between the upper and lower hard layers and the particles are relatively flat, so that the particles can fully roll and consume energy in the gap between the hard layers.

[0059] In order to meet the third function mentioned above, the tires in the tire buffer layer 4 are first symmetrically cut into discarded tire blocks and then filled into the buffer layer. The elasticity of the buffer layer provides displacement recovery force for the structure, suppressing the development of horizontal displacement of the structure under the action of an earthquake. When the residual displacement is large, a detachable displacement recovery device 8 can be set between the shallow buried ground connecting wall 5 and the outer wall 2 of the factory building to quickly restore the residual deformation.

Claims

1. A thin cushion isolation foundation for a nuclear power plant in a high-intensity area, characterized in that: The invention comprises a nuclear power plant building floor (1) and a nuclear power plant building outer wall (2) fixed on the nuclear power plant building floor (1), wherein the nuclear power plant building floor (1) is provided with a plurality of grouting holes (101); a foundation pit bottom (6) is provided below the nuclear power plant building floor (1), and a pile group foundation (7) is provided below the foundation pit bottom (6); a single-layer pebble cushion (3) is provided between the nuclear power plant building floor (1) and the foundation pit bottom (6), and the grouting holes (101) are communicated with the single-layer pebble cushion (3) for allowing slurry to enter the single-layer pebble cushion to bond the pebble particles; a shallow ground connection wall (5) is provided below the ground outside the nuclear power plant building outer wall (2); and a tire buffer layer (4) for limiting the horizontal displacement of the nuclear power plant is provided between the nuclear power plant building outer wall (2) and the shallow ground connection wall (5).

2. The thin cushion isolation foundation for a nuclear power plant in a high-intensity area according to claim 1 is characterized in that: A detachable displacement recovery device (8) is provided between the shallowly buried connecting wall (5) and the outer wall (2) of the nuclear power plant building.

3. The thin cushion isolation foundation for a nuclear power plant in a high-intensity area according to claim 1 is characterized in that: The grouting holes are arranged in the central area and the peripheral area of ​​the nuclear power plant building floor (1); the spacing between the grouting holes in the central area is 0.05 to 0.1 times the length of the long side of the nuclear power plant building floor (1) according to the need for shear resistance, and the spacing between the grouting holes in the peripheral area is 0.05 to 0.2 times the length of the long side of the nuclear power plant building floor (1).

4. The thin cushion isolation foundation for a nuclear power plant in a high-intensity area according to claim 1, characterized in that: The tire buffer layer (4) is filled with cut and processed waste tire blocks.

5. The thin cushion isolation foundation for a nuclear power plant in a high-intensity area according to claim 1, characterized in that: The particle size of the pebbles in the single-layer pebble cushion is 25 cm to 40 cm.

6. The thin cushion isolation foundation for a nuclear power plant in a high-intensity area according to claim 1, characterized in that: The filling height of the tire buffer layer (4) is 1 / 4 to 1 / 2 of the buried depth of the nuclear power plant building floor (1).

7. The thin cushion isolation foundation for a nuclear power plant in a high-intensity area according to claim 1, characterized in that: The horizontal gap between the outer side of the nuclear power plant building outer wall (2) and the inner side of the shallow ground connection wall (5) ranges from 0.5m to 3.0m.

8. The thin cushion isolation foundation for a nuclear power plant in a high-intensity area according to claim 2, characterized in that: The detachable displacement recovery device (8) comprises a plurality of detachable actuators (801) and an electronic control system (802); the detachable actuators (801) are arranged between the shallow ground connection wall (5) and the outer wall (2) of the nuclear power plant building and are located above the tire buffer layer (4).

9. A construction method for a thin cushion isolation foundation for a nuclear power plant in a high-intensity area as claimed in claim 1, characterized in that: The steps include: (A1) Clean and level the construction site, dig a slot, prefabricate a shallow ground-connected wall (5) steel cage on the ground, place it into the slot using a lifting device, pour concrete to form a shallow ground-connected wall (5), then excavate the soil inside the wall. After excavating to the designed elevation, use a pile driver to complete the construction of the pile group foundation (7) from the inside out one by one; (B1) pouring a reinforced concrete bottom cover (6) on the bottom surface of the foundation pit, laying a single pebble cushion layer (3) on the bottom cover layer after it is leveled and has formed strength, prefabricating the nuclear power plant building floor (1), and reserving a plurality of grouting holes (101), and grouting the plurality of grouting holes (101) in batches; using a lifting device to place the prefabricated nuclear power plant building floor on the pebble cushion layer, grouting the first batch of grouting holes is completed, and grouting of the remaining batches of grouting holes is subsequently performed as needed; (C1) Tie the steel bars of the nuclear power plant building's outer wall (2), install the wall formwork, pour concrete, complete the nuclear power plant building's outer wall (2), and then continue the construction of other structures and equipment of the nuclear power plant; (D1) The cut waste tire blocks are filled between the shallow ground connection wall (5) and the outer wall (2) of the nuclear power plant building to form a tire buffer layer (4).

10. A construction method for a thin cushion isolation foundation for a nuclear power plant in a high-intensity area as claimed in claim 2, characterized in that: The steps include: (A2) Clean and level the construction site, dig a slot, prefabricate a shallow ground-connected wall (5) steel cage on the ground, place it into the slot using a lifting device, pour concrete to form a shallow ground-connected wall (5), then excavate the soil inside the wall. After excavating to the designed elevation, use a pile driver to complete the construction of the pile group foundation (7) from the inside out one by one; (B2) pouring a reinforced concrete bottom cover (6) on the bottom surface of the foundation pit, laying a single pebble cushion layer (3) on the bottom cover layer after it is leveled and has formed strength, prefabricating the nuclear power plant building floor (1), and reserving a plurality of grouting holes (101), and grouting the plurality of grouting holes (101) in batches; using a lifting device to place the prefabricated nuclear power plant building floor on the pebble cushion layer, grouting the first batch of grouting holes is completed, and grouting of the remaining batches of grouting holes is subsequently performed as needed; (C2) Tie the steel bars of the nuclear power plant building's outer wall (2), install the wall formwork, pour concrete, complete the nuclear power plant building's outer wall (2), and then continue the construction of other structures and equipment of the nuclear power plant; (D2) filling the cut waste tire blocks between the shallow ground connection wall (5) and the outer wall (2) of the nuclear power plant building to form a tire buffer layer (4); (E2) A detachable displacement recovery device (8) is arranged at the position of the outer wall (2) of the nuclear power plant building outside the internal floor slab of the nuclear power plant building to recover the irreversible horizontal displacement existing after the earthquake, and a batch of grouting holes (101) are grouted to restore the horizontal stiffness of the foundation.

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