Earthquake resistant joint for underground structure against longitudinal seismic displacement
Some underground structures have experienced significant damage by earthquake, and it is recognized that the most critical deformation mode of underground structure constructed near the ground surface is the longitudinal compression-extension mode. Earthquake resistant joints are often applied against this mode, and the effectiveness is recognized by experience. However, the effect have not correctly evaluated by analytical method. To understand the effects of the joints for the mode, theoretical solutions are derived. Numerical result shows that maximum or minimum longitudinal axial stress of the structure is decreased around the intermediate part of structures by earthquake resistant joints. However, it may be not decreased around the joints. Surface loading between the ground and structures in longitudinal direction are highly increased by the existence of the joints. In actual, there will be slipping between the ground and structures around the joint, and the slipping will improve the seismic resistance of the structure.