CN-115977136-B - Design method of large-diameter high-temperature molten salt storage tank foundation in shallow bedrock area

Abstract

The invention discloses a design method of a large-diameter high-temperature molten salt storage tank foundation in a shallow bedrock area, which mainly comprises the following construction steps of filling a graded sand stone cushion layer, burying a deep ventilation pipe at the top of a sand stone top layer, mounting a steel ring wall, filling artificial ceramsite soil in the steel ring wall, burying a temperature detector in the ceramsite soil, and finding a slope on a sand layer on the top surface of the ceramsite soil. Wherein the steel annular wall design comprehensively considers the first state and the second state. And (3) deducing a steel ring wall hoop stress calculation formula according to stress analysis of the steel ring wall under the load of the upper storage tank. And in the second state, a calculation model is built according to the thermal conduction analysis of the steel ring wall under the constraint of the soil body, so that the steel ring wall stress calculation result is obtained. The safe and reliable high-temperature molten salt storage tank foundation is designed by comprehensively considering the two states, and the designed high-temperature molten salt storage tank foundation is short in construction period and easy in quality control.

Inventors

• WANG JUNFENG
• DENG YUTING
• LIU JINHONG
• KE YANG
• Yan Menghui

Assignees

• 东华工程科技股份有限公司

Dates

Publication Date

20260505

Application Date

20221013

Claims (4)

1. 1. A design method of a large-diameter high-temperature molten salt storage tank foundation in a shallow bedrock area is characterized by comprising the following steps: Firstly, digging out a weak soil layer at the top of a bedrock, and tamping graded sand and stone in layers, wherein the thickness of each layer is not more than 200mm, and the compaction coefficient is not less than 0.96; setting a circle of high-temperature resistant plain concrete ring beam at the top of the grading sand stone, leveling the top of the ring beam by adopting a high-temperature resistant Wen Guanjiang material, and providing a foundation for positioning a steel ring wall; Determining the thickness of the tank bottom heat insulation material according to thermal conduction analysis, wherein the tank bottom heat insulation material adopts ceramsite, and then the ceramsite is restrained by a steel ring wall; step four, realizing a real-time temperature monitoring function at different depths of the tank bottom; setting a heat-resistant concrete annular foundation of the tank wall at the inner side of the top of the steel annular wall, wherein the annular foundation consists of precast concrete beam sections with the length of not more than two meters, and Z-shaped expansion joints are arranged between each two sections; In the third step, the strength checking is carried out on the steel ring wall, and the internal force of the steel ring wall mainly considers the following two states: the first state is that the steel ring wall generates annular tensile stress under the action of active ceramsite soil pressure in the steel ring wall and passive gravelly soil pressure outside the steel ring wall; The second state is that heat is transferred from the bottom of the high-temperature molten salt storage tank to the top and the bottom of the steel ring wall, a temperature field is formed in the steel ring wall, the temperature at the top of the steel ring wall is highest, the temperature at the bottom of the steel ring wall is lowest, and stresses in different directions can be generated in the steel plate under the action of the temperature field; In the first state, the theoretical value deduction process of the hoop tensile stress under the action of the tank bottom pressure is as follows: At any height Net internal pressure of steel ring wall ; The balance inside the steel ring wall is: ; Derived from formula (2) ; Substituting the formula (1) into the formula (3), ; The finishing type (4) is carried out to obtain, ; Due to The maximum value of the hoop tensile stress of the annular steel plate is at the top of the steel annular wall: I.e. In the time-course of which the first and second contact surfaces, ; Wherein h is the distance (m) between the calculated section and the top surface of the steel ring wall, D is the diameter (m) of the steel ring wall, q is the tank bottom compressive stress (kPa), K a is the active soil pressure coefficient of the tank bottom heat insulation material, gamma is the weight of the tank bottom heat insulation material (kN/m 3 ）;γ s is the weight of backfill outside the steel ring wall (kN/m 3 ）;K p is the passive soil pressure coefficient outside the steel ring wall, F t is the circumferential tension of the steel ring wall; in the second state, the counterforce of the distributed soil outside the steel annular wall is set to be p s ,p s =k s ·v+P s0 under the action of a temperature gradient, and k s =mh; Wherein p s is the distribution soil counter force (kPa) outside the steel ring wall under the action of temperature, k s is the horizontal counter force coefficient (kN/m 3 ) of the soil outside the steel ring wall, v is the horizontal displacement value (m) of the steel ring wall for compressing the soil at the distribution soil counter force calculation point under the action of temperature, m is the proportionality coefficient (kN/m 4 ) of the horizontal counter force coefficient of the soil, the value is taken according to the horizontal load test and the regional experience of the pile, p s0 is the initial distribution soil counter force outside the steel ring wall, the value is taken according to the active soil pressure distribution (kPa), and h is the depth from the calculation point to the ground.
2. 2. The method for designing the large-diameter high-temperature molten salt storage tank foundation in the shallow bedrock area according to claim 1, wherein the method comprises the following steps: In the fourth step, the sleeve pipes are buried at different depths of the porcelain granules in the process of filling the heat-insulating porcelain granules at the bottom of the tank in a layering manner, holes are reserved at specific positions on the steel annular wall, and temperature detection signals are transmitted into the sleeve pipes and then led out from the round holes on the steel annular wall.
3. 3. The method for designing the large-diameter high-temperature molten salt storage tank foundation in the shallow bedrock area according to claim 1, wherein the method comprises the following steps: and step five, after the upper tank wall is installed in place, high-temperature resistant grouting material is filled between the tank bottom plate and the annular foundation, and glass fiber is filled between the steel annular wall and the annular foundation.
4. 4. The method for designing the large-diameter high-temperature molten salt storage tank foundation in the shallow bedrock area according to claim 3, wherein the method comprises the following steps: The annular foundation is used for reducing differential settlement between the tank bottom plate below the tank wall and the tank bottom plate in the middle of the tank body so as to reduce the deformation and internal stress of the tank body caused by the differential settlement.

Description

Design method of large-diameter high-temperature molten salt storage tank foundation in shallow bedrock area Technical Field The invention belongs to the technical field of design and manufacture of storage tank foundations, and particularly relates to a design method of a large-diameter high-temperature molten salt storage tank foundation in a region with shallower bedrock. Background The high-temperature molten salt storage tank is core equipment of molten salt heat storage technology, and is mainly applied to the scenes such as photo-thermal power generation, clean heat supply and the like. The fused salt heat storage technology can help to store electric energy such as abandoned wind, abandoned photoelectric and the like, release the electric energy when needed, reduce the energy cost of users, improve the energy utilization rate of the whole power generation system and realize peak clipping and valley filling. And the output power of photoelectricity and wind power is smoothed, and the power generation capacity of new energy sources is improved. The design method of the high-temperature molten salt storage tank foundation does not have national standard or industry regulations at present, and most of the existing storage tank foundations adopt a concrete bottom plate or concrete annular wall scheme, so that the characteristics of high bottom temperature, large base diameter (the diameter is more than 40 m) and long annular wall length of the large-diameter high-temperature storage tank are achieved. The concrete bottom plate or the concrete annular wall is adopted to solve the problems of long construction period and difficult quality control caused by large-volume concrete pouring. Therefore, it is necessary to invent a design method of a large-diameter high-temperature molten salt storage tank foundation in a region with shallow bedrock to solve the above problems. Disclosure of Invention Aiming at the problems, the invention provides a design method of a large-diameter high-temperature molten salt storage tank foundation in a shallow region of bedrock, which aims to solve the problems in the background technology. In order to achieve the purpose, the invention provides the following technical scheme that the design method of the large-diameter high-temperature molten salt storage tank foundation in the region with shallower bedrock comprises the following steps: Firstly, digging out a weak soil layer at the top of a bedrock, and tamping graded sand stones in layers, wherein the thickness of each layer is not more than 200mm, and the compaction coefficient is not less than 0.96; Setting a circle of high-temperature resistant plain concrete ring beam at the top of the grading sand stone, leveling the top of the ring beam by adopting a high-temperature resistant Wen Guanjiang material, and providing a foundation for positioning the steel ring wall; determining the thickness of the tank bottom heat insulation material according to thermal conduction analysis, wherein the tank bottom heat insulation material is generally ceramsite and is restrained by a steel ring wall; step four, realizing a real-time temperature monitoring function at different depths of the tank bottom; And fifthly, arranging a heat-resistant concrete annular foundation of the tank wall on the inner side of the top of the steel annular wall, wherein the annular foundation consists of precast concrete beam sections which are not more than two meters, and Z-shaped expansion joints are arranged between each two sections. Further, in the first step, the thickness of the graded sand backfill of the top surface of the bedrock=the depth of embedding the bedrock, the heat preservation thickness of the tank bottom, and the thickness of the graded sand at the bottom of the heat preservation layer. Further, in the second step, grading sand stones are paved inside the ring beam, steel pipes are buried in the grading sand stones, and the heat conduction capacity of the grading sand stone layer is reduced. Further, in the third step, the strength of the steel ring wall is checked, and the internal force of the steel ring wall mainly considers the following two states: the first state is that the steel ring wall generates annular tensile stress under the action of active ceramsite soil pressure in the steel ring wall and passive gravelly soil pressure outside the steel ring wall; and in the second state, heat is transferred from the bottom of the high-temperature molten salt storage tank to the top and the bottom of the steel ring wall, a temperature field formed in the steel ring wall has the highest temperature at the top of the steel ring wall and the lowest temperature at the bottom, and under the action of the temperature gradient, stresses in different directions can be generated in the steel plate. Further, in the first state, the theoretical value deduction process of the hoop tensile stress under the action of the tank bottom pressure is as