Abstract: On the basis of finite element method combined with viscous-elastic artificial boundary， the seismic wave input was transformed into equivalent node force， and a three-dimensional plane SV wave input method based on wave theory was established. The accuracy of seismic wave input method and the valid of the numerical analysis were proved by the half-space example. Then the mechanical properties of the shear keys of the segment joint in Hong Kong-Zhuhai-Macao Bridge immersed tunnel considering the static and dynamic water effects of the upper sea water were studied based on the established seismic wave input method. The results show that the vertical acceleration is also generated by horizontal earthquake， but the value of the vertical acceleration is small. The compressive stress is the largest stress on the shear key under earthquake， while the tensile stress is relatively small. Because the tensile stress of shear key is mainly concentrated on the locations where the shear key is connected with the main body of the immersed tunnel， tensile cracks are prone to occur. The main failure mode of horizontal shear keys is tensile failure. The setting direction of the shear key in the joint determines the shear distribution at the root of the shear key， and most of the shear forces are resisted by the shear key in the same direction with the displacement.

Key words: immersed tunnel; mechanical properties; finite element; shear key; seismic wave