Dynamic Response Analysis Of Underground Structure

In recent years, underground structures have been utilized widely in energy sources, traffic, city construction, and national defending engineering, etc. As most areas of our country belong to earthquake-fortified regions, anti-seism and security evaluation of underground structures has important academic theoretical and practical value. Project planners are paying much more attention to it.On the basis of relevant boundary conditions and the establishment of reasonable numeration model, this paper analyzes layering level soil and underground structures through utilizing FEM (finite element method). The calculate scope of ground is studied. Results indicated that three times width of bottom is rational in computation. It can economize computer memory and enhance the calculation efficiency.The computing precision of three type conditions such as free boundary, viscous boundary and fixed boundary is compared. Based on various boundary conditions, the seismic response studies of a tunnel are executed by using finite element method. The earthquake responses of the tunnel are overestimated when free and fixed boundary is used. The results showed that the viscous boundary is more reasonable than the other two.Also, this article researched on seismic responds of free ground. The research indicated that the earthquake response of soft soil is related with not only dynamic characteristic of soil, but also earthquake wave.Finally, this paper cites an example to provide the scientific base for the design underground structures. The study showed that ill uniformity of soil stratum distributing has great effect on the transverse displacement of the soil stratum. Underground structures should have sufficient stretchiness for enduring the displacement of soil stratum, therefore, avoid being cut and destroyed. Under the seismic excitation, so as to monolithic subsidence is easy to occur. Moreover, from the point of the whole structure, the crust and corners of the station are very incidental to be destroyed. As a result, in the course of design and construction, must more attention should be paid to them.