Seismic Response Analysis On Frame-Shear Wall Structure And Karst Soil-Foundation Interaction

The karst areas in China accounts for about one third of the national land area. With the rapid development of economy and the acceleration of urbanization, constructing buildings on complex karst geological foundation is becoming more popular, and the major design approach remains employing conventional method (artificially analyze soil, foundation and superstructure respectively) or experience, which is apt to cause human error. Especially conducting seismic analysis of the buildings, there will be discrepancy between calculation results and the actuality. Therefore, the seismic study on the superstructure-soil-foundation interaction system in karst area is necessary.Based on the research results in home and abroad, this thesis conducts the following studies on frame-shear wall structure and karst soil-foundation interaction with the numerical simulation methods.(a) Research status of the interaction system at home and abroad is briefly stated, and relevant literature review is done to get to know the general engineering geology situation in karst area. The most distinctive feature of karst area is the widespread distribution of carbonate rock, and red clay is the most typical soil in karst area. Because of its distribution characteristics and the influence of water and other geological process, red clay layer usually contains soil caves, whose size and location should be ascertained for following corresponding process.(b)The characteristics of "small magnitude earthquake of high intensity" and the principle and adjustment of seismic wave selection in karst area are elaborated, then the equivalent linearization method is utilized to inverse the selected seismic wave to the bedrock, and compare the selected seismic wave with surface seismic wave. The result demonstrates that the soil layer in karst area has amplification effect and filter action on the seismic wave.(c)The mechanism of the superstructure-soil-foundation interaction system, the effect of superstructure stiffness, foundation stiffness, soil stiffness on the interaction system are described. The three-dimensional finite element models of interaction system without soil caves and interaction system with soil caves are established. Contrastive analysis is conducted between this two models on their displacement, acceleration, interlayer displacement and internal force. The results indicates that the calculation results of the model of interaction system with soil caves is larger than that without soil caves, which means the existence of soil caves has obvious influence on the dynamic response of the soil-foundation-superstructure interaction system in karst area.(d)Under the influence of seismic action, through changing the parameters of the soil caves, i.e., cave size, buried depth, horizontal location, shape, quantity and location of the soil cave group, this thesis studies the influence of soil cave changes on dynamic response of superstructure, and analyzes the displacement, acceleration, displacement and internal force of different models. The results shows that the size, buried depth, horizontal location, quantity of the soil caves and the soil cave groups of different location have remarkable influence on structure dynamic response, which provides references for the aseismic design of high-rise building in karst area.