| With the rapid development of China’s transportation and the urgent need for cities to create three-dimensional traffic system, more and more subway tunnels go through road tunnels from the top or the bottom of them. However, China is the world’s largest seismic active area with shallow earthquakes, the earthquake activity is frequent and there develop a lot of fault belts. Reflection and diffraction of seismic wave is very clear.The intersecting tunnel is shock by seismic wave of reflection and diffraction and the influence between them is enormous.There is not too much research on the three-dimensional traffic system at home and abroad, so it is necessary to study on seismic response of the major structure. Therefore, this paper studies on the intersecting tunnel through investigation,theoretical study and numerical simulations.The results from seismic numerical simulations on the surrounding rock in grade Ⅳ and Ⅴ of Ⅷ earthquake intensity area show: displacements and internal forces of grade Ⅴ surrounding rock are significantly larger than grade Ⅳ, in other words,soft rock is more sensitive on earthquake. The paper indicates that reasonable distance of parallel tunnels should be more than1.5time of tunnel diameter and orthogonal tunnels1time. Connection position between connected aisle and tunnel is seismic weak region where the structure produces stress concentration easily and destroyed. Dynamic response of connecting parts between shaft and tunnel is greater than other parts which is the weak region of structure under earthquake.Research on the effect of shock absorption of intersecting tunnel indicates:adopting tunnel section made of smooth rounded curves can reduce displaments,which also increase the internal force slightly.But there is a slight increase in the internal forces. A shock-absorbing layer between the rock and the lining separates them from each other, meanwhile vibration-absorptive material absorbs seismic energy which plays a good role in seismic resistance;It is not satisfactory and economic to improve its seismic performance through increasing the stiffness of the structure;while reinforcement of surrounding rock can improve the mechanical properties of the structure which has a good effect on seismic resistance. |
