Influence Of Pile-soil On Settlement And Dynamic Response Of Large LNG Storage Tank

In recent years,the use of natural gas in China is gradually increasing.In order to meet the demand,large LNG tanks have been built in many areas.So far,the construction technology of large LNG tanks in China is not perfect,especially in China,there is no perfect specification for reference,It is significant to study the structural response of storage tank under the action of settlement and earthquake.In this paper,the finite element software is used to establish the overall model of large LNG storage tank with pile-soil.The settlement of LNG storage tanks under three kinds of pile foundations and the dynamic response analysis considering the pile soil structure interaction are carried out.The main contents of this paper are as follows:(1)This paper summarizes the existing settlement research methods of large-scale LNG storage tank,establishes the settlement analysis model of large-scale LNG storage tank,studies the settlement of large-scale LNG storage tank under different pile foundations,adjusts the butterfly settlement of storage tank by increasing the length and diameter of internal pile,and analyzes the stress of upper structure of storage tank after adjustment.(2)This paper summarizes the modal analysis method when the tank is full of liquid,and summarizes the liquid-solid coupling method of the tank.The additional mass method is used to analyze the modal of the large LNG tank,and the first eight order vibration frequencies of the outer tank of the LNG tank are extracted.The modal is compared with the existing model and the modal obtained by the existing equivalent volume method,and the equivalent elastic modulus method is adopted for verification After the simplification of the reinforced concrete outer tank,whether the outer tank can be used for dynamic analysis,the fourth-order beam vibration frequency and modal pictures of the inner tank of LNG are extracted,and the correctness of the constraint mode of the inner tank model is verified by using the calculation formula of the liquid-solid coupling frequency of the steel tank,so as to ensure the accuracy of the model establishment.(3)This paper summarizes and introduces the setting method of soil boundary conditions in the pile-soil-structure interaction of different pile foundation finite element models by using finite element method.The finite element model is established by using the remote free boundary method.The structure of three pile foundation schemes with the same internal pile and external pile,increasing the length of internal pile and increasing the diameter of internal pile under the action of three horizontal unidirectional seismic waves is analyzed The dynamic response of pile foundation and superstructure are obtained.The analysis results show that: when the arrangement of inner pile and outer pile of LNG storage tank is the same,it will lead to larger butterfly settlement,which will lead to greater stress on the outer concrete tank and bottom plate of LNG storage tank,but has less impact on the inner tank;the method of increasing the length of inner pile to adjust the butterfly settlement of LNG storage tank is more effective than the method of increasing the diameter of pile The results show that the method of increasing pile length and reducing pile diameter can be adopted to reduce the internal settlement of LNG storage tank at the same time;under the action of horizontal seismic wave,the stress of outer pile top is greater than that of inner pile top,and the stress of pile top under the action of SHM wave is the largest;under the same seismic wave,the stress of model tank top of pile foundation layout scheme FA1 is the largest,while that of pile foundation layout scheme FA3 is the largest The model of tank top stress is minimum.