地震作用下各向异性地基的动力响应--离心机模型试验研究

Dynamic response of anisotropic foundation under earthquake:experimental research on centrifuge model

砂土颗粒之间接触的法向分布和颗粒形状所引起的内在各向异性会对地基的地震响应有明显的影响。为了深入认识砂土内在各向异性对地层动力响应的影响,制作了专门的离心机模型箱以控制砂土的不同沉积方向模拟砂土的内在各向异性,并且通过一系列离心机振动模型试验再现了砂土内在各向异性对砂土动力学特性的影响,包括对地层加速度、位移和超孔隙水压力的影响。研究发现,尤其在饱和情况下,砂土的内在各向异性对砂土的动力学特性影响非常大,沉积方向为90度的砂样模型抗液化能力明显较差,导致较大的沉降。为了更加准确的预测结构物在地震区的动力特性,建议在工程设计中应考虑砂土内在各向异性的影响。

Intrinsic anisotropy caused by the contact normal distribution and particle shape may have obvious effect on the seismic response of the foundation. To examine the effect of intrinsic anisotropy on seismic response of earth layer, a special rigid container was made to control different directions of soil deposition, simulate the anisotropy of the sand and reproduce the effect of the intrinsic anisotropy on dynamic behavior of the sand, including acceleration, velocity, displacement and super pore water pressure through a series of model tests. Test results show that the effect is obvious especially in the saturated condition, while the liquefaction resistance capability of the sand sample modeled with 90- deposition direction is less obvious, which would lead to large settlement. To better predict the dynamic behavior of structures in seismic area, it is suggested to consider the effect of the intrinsic anisotropy of the sand in engineering.