With the recent increase in occurrence and magnitude of the earthquake in Korea, the safety of public facilities such as cut-and-cover tunnels cannot be guaranteed since such constructed and designed structures before 2005 has not been designed to resist the earthquake loads. Therefore, seismic code for underground structure were established in 2005 and it is required to follow codes. RDM(Response Deformation Method) is mainly used to design cut-and-cover tunnels. In RDM procedure, dynamic inertial forces represented as equivalent static loads are determined with reference to seismicity of construction sites, ground characteristics, structural ductility and associated limit state of reinforced concrete. This simplified way of design works well for particular types of structures but is no longer efficient for complex structures having interaction with the surrounding soil. Dynamic forces that arise in cut-and-cover tunnels have much to do with deformation of soil. Furthermore, dynamic soil pressure applied to cut-and-cover tunnels is affected by stiffness reduction of cut-and-cover tunnels members, ductility of structures and hysteresis damping characteristics.
The main goal of this study is to improve rationally the design for cut-and-cover tunnels under seismic excitation. To achieve this goal, two seismic analysis methods of cut-and-cover tunnels were investigated to compare the results from RDM and RAM(Response Acceleration Method), respectably. To verify the computational result, centrifuge test were carried out and discussed. Experimental work for cut-and-cover tunnels, which is used for infrastructure in Korea, is carried out to verify cut-and-cover tunnels model in the level structure subjected to Kobe and Northridge earthquakes.
The analytical and experiment results of cut-and-cover tunnels indicate that the deformation of cut-and-cover tunnels from RDM is smaller than the result from RAM and centrifuge test. To improve RDM, adjustment for response adjusting factor, resistant factor of ground layer are suggested.