Study On Seismic Isolation Behavior Of Base Isolation Cushion Of Desert Sand

Earthquake disasters occur frequently in China,and a large number of houses in tovnship areas have been seriously damaged and collapsed,resulting in heavy casualties and property losses.Because of the relatively backward economic conditions in rural areas and the poor seismic performance of houses,the damage degree of houses in rural areas is much higher than that in cities when they are subjected to the same intensity earthquake.Therefore,it is of great practical significance to study low-cost seismic isolation technology for buildings in rural areas.Based on the key research and development project of the autonomous region(2016KJHM38),combined with the regional characteristics of the Northwest region,this paper puts forward the isolation cushion of desert sand.By using the method of combining experiment with finite element simulation,this paper systematically studies the working mechanism and seismic isolation effect of the isolation cushion of desert sand.The purpose is to study the low-cost isolation and absorption technology to guide engineering practice.The research work and conclusions are as follows:(1)Shaking table tests were carried out on cushion cushion of desert sand to study its seismic isolation performance under seismic action.The experimental results show that the isolation cushion of desert sand mainly consumes seismic energy and reduces structural seismic response by sliding on the desert sand cushion through the upper structure,friction energy dissipation between the bottom of the structure and the isolation cushion,and sliding energy dissipation between the particles in the desert isolation cushion.Under earthquake excitation,the working process about isolation cushion of desert sand can be divided into two stages:occlusion consolidation and sliding isolation.In the occlusion consolidation stage,the isolation cushion of desert sand does not play a role of isolation.In the sliding isolation stage,the isolation cushion of desert sand plays a role of isolation and reduces the acceleration response of superstructure.The division of each stage is related to the input seismic intensity and the friction characteristics of desert sand.(2)Based on the shaking table test results and taking the seismic decrease coefficient P(the ratio of the output of the superstructure to the input acceleration amplitude of the shaking table)as the index,this paper quantitatively evaluates the shock absorption effect of the isolation cushion of desert sand,and discusses the influence of the parameters such as the intensity of ground motion,the thickness of the cushion,the base pressure and the moisture content of the cushion on the damping law of the isolation cushion of desert sand.The results show that the greater the peak value of seismic wave is,the more obvious the shock absorption effect of isolation cushion of desert sand is;with the increase of cushion thickness,the shock absorption coefficient decreases gradually,and the seismic isolation effect of desert sand cushion is more and more obvious,but the bottom pressure of upper structure has little effect on the shock absorption effect of isolation cushion of desert sand;the cushion moisture content increases,and the shock absorption effect of base isolation cushion of desert sand becomes worse.(3)The isolation model about the desert sand cushion is established by ANSYS software.The reliability of the model is verified based on the test results.Taking common masonry structure in rural areas as an example,the seismic response of masonry structure after setting desert sand cushion is studied.The simulation results show that ANSYS software can better simulate the isolation performance of the isolation cushion of desert sand.The vibration period of masonry structure is prolonged after using the isolation cushion of desert sand.The deformation of the structure mainly occurs in the isolation layer,while the upper structure is similar to the overall translation.Under seismic action,the isolated structure slides on the desert sand isolation cushion,which effectively reduces the seismic response of the upper masonry structure.The desert sand isolation cushion is an economical and effective seismic reduction measure.