Study on Response Acceleration Methods for Transverse Seismic Response Analysis of Tunnel Structures

The response acceleration method (RAM) has widely been used in transverse seismic response analysis of tunnels, but many details of this method are not clear enough. We have made a simple theoretical derivation of the RAM of tunnel structure and implemented it in the program. From the theoretical equation, we cannot see the influence of boundary width, element type and burial depth of underground structure on the accuracy of the RAM. The various site types and depths of burial of the tunnels are set as the reference model. The structural internal forces of the reference model are calculated by the RAM and time-history method. The reasonable boundary width, different element types and accuracy varying with the buried depth of RAM are evaluated. The probability demand model and the tunnel's seismic vulnerability curve to evaluate tunnels transverse seismic performance by utilizing a modified incremental dynamic analysis (IDA) method which is used by the RAM. The results indicate that the artificial boundary width can be eight times of the structure width under site types II–IV. When the beam element is used to simulate the underground structure, the position of the beam element should be taken at the center of the underground structure lining and connected with the soil plane element by rigid arm. The RAM has high accuracy in different burial depths and soil layers. The modified IDA method has the advantages of small workload, time-saving, convergent and simple calculation.