Rows of elastic hollow pipe piles as isolation barriers for plane SV waves

The soils and pipe piles are considered as homogeneous isotropic elastic media, and the isolation of incident plane SV waves by the discontinuous barriers composed of several rows of hollow pipe piles is simplified as a two-dimensional plane problem. The conformal mapping method of complex functions and the expansion method of wave functions are adopted, the stresses and displacements at the boundaries between the pipe piles and their adjacent soils are considered to be continuous and the inner sides of the pipe piles to be free, and then the theoretical solutions are obtained for the isolation problem. They are compared with the results simulated by FEM software of ABAQUS and proved to be correct. Finally, some factors that influence the isolation effects are studied, such as the wall depths, rows and total number of pipe piles and frequencies of incident plane SV waves. The results show that: the isolation effects increase when the wall depths of the pipe piles decrease; the best isolation areas develop to the far side when the number of rows increases from one to two, while they develop to the bilateral sides when the number of rows increases from two to three; the isolation effects increase obviously in the barrier width with the total number of pipe piles as to the same number of rows; and the isolation effects decrease when the incident frequencies of SV waves increase. These conclusions will provide some theoretical bases and references for the design of vibration isolation with several rows of pipe piles.