Research On Dynamic Response Of Underground Structure Mid-Pillar Under Vertical Seismic Excitation

With the development of underground constructing, more and more underground structures are put into use. Due to a lot of underground structures are damaged in the Japan's Kobe earthquake, more and more scholars attention to research the underground structures seismic problems. Although underground structures seismic research has made a lot of achievements in this field, there are few systematic underground structure mid-pillar under vertical seismic excitation research in the past. There were many deficiencies in research. 1) Previous studies mainly focus on shallowly buried underground structure and each part of the underground structure, and depth or change of the buried depth were neglected. 2) Previous studies focus on numerical simulation, the lack of theoretical research results.This paper studies the dynamic response of underground structure mid-pillar under vertical seismic excitation and analyzes the seismic ability of underground structure mid-pillar. Obtaining some main conclusions by using calculation and analysis of the example.(1) Development a method of solving dynamic response of box underground structure(1) Development a method of solving dynamic response of box underground structure mid-pillar under vertical seismic excitation by using simplified model. Through the analysis process, when the natural frequency of the underground structure is compared to the vertical earthquake frequency is extremely large, the underground structure is basically the same as the motion form of foundation soil.(2) Analysis of four simplified models of single, double, double span and triple span by using structural dynamics methods. Firstly, solving motion equation for roof slab beam and bottom slab beam. Secondly, Obtaining the deflection curve equation of roof slab beam and bottom slab beam by motion equation of roof slab beam and bottom slab beam. Thirdly, the shear force of roof slab beam and bottom slab beam can be obtained from the deflection curve equation of roof slab beam and bottom slab beam. Finally, the stressing of mid-pillar is obtained indirectly. The single layer underground structure mid-pillar will be significantly affected by vertical seismic excitation.(3) The result show that force of the double-layer underground structure mid-pillar same as single-layer. The mid-pillar in the double-layer underground structure will still significantly influenced under vertical seismic excitation. The lower mid-pillar is more sensitive than upper mid-pillar, which is more easily affected.(4) One of the vertical surrounding rock stress calculation theory was called the Terzaghi theory is modified. The example show that modified Terzaghi theory more realistic. The modified Terzaghi theory has a better accuracy than Terzaghi theory.(5) The stress of the mid-pillar in the underground structure under vertical earthquake is analyzed by modified Terzaghi theory when the buried depth is changed. The example show that modified Terzaghi theory more realistic than Promojiyfakonov theory and Terzaghi theory. The seismic theory of the mid-pillar in the underground structure has provided a method from shallow buried to the deep buried by derivation.