Study On Seismic Response Law Of Shallow Double-hole Tunnels

In our country, with the implementation of the western development strategy, a largenumber of tunnels in highway, railway, water conservancy and hydropower engineering willbe built in the mountainous and hilly areas. People used to think that the tunnel restrained bysurrounding rock will have better seismic performance, but a variety of earthquake data showsthat many strong earthquakes have caused severe damage on the underground structure. Ourcountry is located at the confluence of two major seismic zone in the world, the seismicactivity is frequent, especially in the Wenchuan earthquake in2008, a large number of tunnelshave been damaged in varying degrees. This earthquake caused major losses. Therefore, theimportance and urgency of the seismic research of tunnels and other underground structures isincreasing, the shock absorption mechanism of the tunnel remains to be further studied.This dissertation lists a large number of underground structure seismic damage examples,expounds the general damage law of tunnels and other underground structures, summarizesthe present research methods of underground structure seismic analysis. Using the dynamicfinite element method, this dissertation has particularly studied the seismic response law ofcommon shallow double-hole tunnels.Based on the finite element software ABAQUS, we studied the effects of tunnel depth,tunnel space, lining stiffness, the properties of surrounding rock, seismic wave incident angle,seismic intensity and other factors on the seismic response of tunnels, and also analyzed theeffect after adding the shock absorption layer, and some useful conclusions are obtained:(1) The depth of the tunnel increases, the influence of the earthquake is smaller, shallowtunnel are easier to large damage;(2) The tunnel space should not be too small, the seismic response of small space tunnelswill be greatly increased; (3) The tunnel stiffness should not be too high, relatively low tunnel stiffness has betterseismic performance;(4) The level of surrounding rock is higher, the tunnel seismic response is smaller;(5) The tunnel seismic response increases linearly with the earthquake intensity increases,the seismic wave which incident vertically from the bottom of the tunnel causes the maximumdamage;(6) A shock absorption layer between the tunnel and the surrounding rock has gooddamping effect, but the shock absorption material and thickness selection should beappropriate.