波浪作用下成层海床孔隙水压力响应的简化分析

采用不排水条件下孔隙水压力发展模式,作为Terzagh i一维固结方程中考虑波浪循环作用所引起的孔隙水压力源项,对于成层海床建立了推广的一维动力固结方程,运用数理方程中的分离变量法与G reen函数求解了成层海床在波浪作用下残余孔隙水压力的发展规律,进而对成层海床的液化势进行了评判。对比计算与分析表明,海床表层土的渗透性及其厚度对于海床的整体抗液化性能具有显著的影响,低渗透性的表层导致海床孔隙水压力的显著积累,此时表层置换法是防治液化的有效途径。

Simplified procedure for evaluation of residual pore pressure response in layered seabed under wave loading

The built-up pattern of the pore water pressure of sand under undrained shearing induced by wave loading is incorporated with the Terzaghi's equation of consolidation to establish the generalized form of one-dimensional dynamic consolidation equation.The Green's function for the resulting one-dimensional partial differential equation together with the given initial and boundary conditions is obtained by applying the mathematical methods.The whole process of generation and time-dependent dissipation as well as spatial diffusion of the pore water pressure induced by the cyclic action of wave loading can be reproduced by the analytical solution achieved by the method of separation of variables.Based on the computed pore water pressure,the liquefaction potential of layered seabed was evaluated.It is shown that the development of pore pressure and liquefaction potential of the seabed are considerably associated with the permeability and thickness of the surface soil layer and effective precaution to prevent from liquefaction is to improve the permeability of surface layer and the replacement method can be employed for this purpose.