Interaction Of Liquefiable Foundation-Raft-Frame Structure Under Earthquake

In recent years,with the progress of science and technology and the rapid development of the civil industry,the analysis method of the combined action of soil and structural dynamics is often applied to engineering seismic analysis.China has a vast territory and complex and ever-changing geological conditions.The location of buildings often encounters liquefiable foundations.Under the action of earthquakes,the increase in pore water pressure in liquefiable foundations is inconsistent with the dissipation rate.The sharply increased pore water pressure in saturated sands is too late to dissipate quickly,and liquefaction is likely to occur.The liquefaction of the soil will reduce the bearing capacity of the foundation,the lateral displacement of the ground,and the destruction of the structure by subsidence,which will cause serious losses to people's production and life.The problem of earthquake liquefaction and the interaction of soil and structure have caused widespread concern in the engineering community.Sand liquefaction is a complex dynamic fluid-solid coupling process.Accurately and reasonably predicting soil liquefaction,exploring its influencing factors,preventing the occurrence of sand liquefaction and studying the effects of liquefaction on structure are still the focus of future research.In this paper,the foundation-raft-frame structure interaction study is carried out on the common liquefiable site with silty sand interlayer in the seashore.The FLAC3 D finite difference software is used to establish the model of the liquefiable foundation building.The main rules of interaction with the liquefiable foundation are as follows:(1)Consult relevant information,understand the mechanism of sand liquefaction,systematically summarize the research status of sand liquefaction,soil and structural dynamic interaction,and lay the foundation for dynamic analysis of multi-layer liquefiable foundation-raft-frame structure interaction system.(2)Taking building height and raft area as influencing factors,the degree of liquefaction and distribution characteristics of the liquefiable site under earthquake action are studied,and the change law of excess pore pressure ratio,effective stress,and excess pore water pressure in saturated sand is summarized,and analyzed The internal force and settlement deformation law of the building.(3)The influences of the thickness of the overlying soil layer and the thickness of the liquefiable layer on the interaction of the soil and structure under earthquake action are studied,and the effective stress and excess pore water pressure in saturated sand under different working conditions are compared and analyzed.(4)The influence of two factors,the depth of the building foundation and the amplitude of the seismic wave acceleration,on the liquefaction of the soil and the displacement of the building are studied.