Seismic Performance Assessment of Tunnel Structure Based on Incremental Dynamic Analysis

With the frequent occurrence of earthquake disasters in recent years, underground structures in strong earthquake areas have been repeatedly damaged. Long and large tunnel is an important fundamental project for the implementation of China’s western development strategy, and its seismic safety problem is particularly prominent. By introducing incremental dynamic analysis (IDA) and combining with seismic fragility analysis method, a seismic performance assessment method for tunnel structure based on damage coefficient index was proposed. In this method, the damage coefficient of the characteristic part of lining structure after earthquake was taken as the demand measure, and the peak ground acceleration of the earthquake was taken as the intensity measure. Then, the 5-level seismic damage classification standard and 4-level seismic performance level suitable for the seismic safety evaluation of tunnel structure were suggested. Taking a tunnel project as an example, the seismic fragility curves of the characteristic parts of lining structure under different seismic performance levels were obtained through a great deal of nonlinear dynamic time-history calculation. Furthermore, the failure probabilities of lining structure under different seismic fortification standards were analyzed. The results showed that the lining structure was nearly undamaged under 8-intensity frequent seismic load. The probabilities of haunch in nearly intact state and slight damage state were 87.6% and 10.72% under 8-intensity fortified seismic load, respectively. The probabilities of haunch in slight damage state and medium damage state were 68.7% and 20.8% under 8-intensity rare seismic load, respectively. The seismic performance of the haunch, spandrel, arch foot, top arch and bottom arch of lining structure increased in turn under horizontal and vertical seismic motion input. The haunch, spandrel and arch foot were the weak parts of seismic design of lining structure. The method can well consider the randomness of seismic motion, and provide an effective way for the seismic safety evaluation of tunnel structure. The research results can also provide references for seismic design of tunnel structure. © 2019, Editorial Department of Advanced Engineering Sciences. All right reserved.