Abstract:Based on the 1D time domain method for dynamic response analysis of underwater site subjected to obliquely incident seismic waves, the expressions of displacement, acceleration, and stress of underwater site under the incidence of plane P-waves were derived. The effects of water depth on the peak displacement, peak acceleration, peak shear stress, and peak pore water pressure along the vertical depth of soil layer were explored. The numerical results showed that at the same depth of soil layer, when the water depth is less than 1 time the soil thickness, the peak vertical displacement increases with the increase in water depth; when the water depth is greater than 1 time the soil thickness, the peak vertical displacement decreases with the increase in water depth. The relation between peak horizontal displacement and water depth is basically the opposite of the peak vertical displacement. Under the same water depth, the peak vertical displacement and peak vertical acceleration continuously decrease with the increase in soil depth, and the peak horizontal displacement decreases first and then increases. Beyond the range from 0.75 times the soil thickness to the bedrock, the water depth has little effect on the peak shear stress. First, the peak pore water pressure generally decreases and then it increases and decreases gradually.