饱和土中球空腔的瞬态动力响应

采用工程上通用的饱和土力学模型，考虑流体与固全之间的耦合作用，利用Ｌａｐｌａｃｅ变换求解了饱和土中球空腔的瞬态动力响应问题，得到了变换域内的解析解，借助数值Ｌａｐｌａｃｅ换求解了饱和土中球空腔瞬态动力响应的位移、应力及孔压的变化规律，为分析地下结构瞬态动力响应提供了一种有效的方法，模型符合工程实际，有一定的工程应用价值。

TRANSIENT DYNAMIC RESPONSE OF SPHERICAL CAVITY IN SATURATEDSOILS

Saturated soils, which is a kind of two-phase (fluid-soild coupling) medium, is frequently encountered in engineering practice. Since the dynamic response of saturated soils is more complicated than that of uniphase soils, previously, the soils is taken as uniphase medium when dynamic response of soils is studied. Since the Boit's equations for dynamic consolidation and wave propagation of saturated soils was found, the research on saturated soils has been advanced rapidly. Obviously, it is more reseanable and prasticable to adopt two-phase medium model to study the dynamic response of soils than to adopt uniphase medium model.Based on the generally adopted saturated soil model for engineering, and the effect of fluidsolid coupling considered, an analytic solution in the forms of Laplacian for transient dynamic response of spherical cavity in saturated soils is got by Laplace transformation. It can be seen from the analytic solution that the transient dynamic response of spherical cavity in uniphase soils is a speacial case of our study.The Chaxacteristics of the transient dynamic response of spherical cavity in saturated soils is studied numerically by Laplace inversion of the analytic solution. The displacements, stresses and pore pressures at different time and different places under different boundary condition are investigated, and some conclusions are drawn:1) the displacement of the soils's skeleton when the boundary can be drained is very close to that under the case of undrained boundary, and they are all attenuated according to r-2; 2) the stress in soil when the boundary can be drained is very close to that under the case of undrained boundary, and they axe all attenuated according to r-3; 3) the pore pressure at the boundary of the cavity is always zero when the boundary can be drained, but the pore pressure at the boundary is not equal to zero when the boundary can't be drained. The pore pressure in the saturated soils dissipated very quickly under the transient loading.These conclusions can be helpful to engineering practice, and the method presented in the paper provide an effective method for dynamic analysis of saturated soils.