SV波斜入射形成的动应力路径及影响因素分析

Analysis of dynamic stress path due tooblique incidence of SV-waves and its influencing factors

动应力路径是研究场地地震动力响应的关键。基于波动理论,推导了半无限弹性空间中任一深度处由SV波斜入射产生的动应力。在采用较大土体刚度参数,且SV波为垂直入射特例时,该方法与土动力学估算地震动应力的常规简化方法结果一致。揭示了SV波斜入射下形成的动应力路径特征,从数学上证明了SV波斜入射产生的动应力在双剪应力分量(偏差正应力和水平剪应力)组成的平面中形成斜椭圆形,并进行了参数敏感性分析,表明入射角、泊松比和单位波长深度是影响应力路径的根本因素,为进一步研究斜入射地震波作用下场地动力响应奠定了理论基础。

Dynamic stress path is the key to study site seismic responses. Based on the wave theory,dynamic stress produced due to oblique incidence of SV-waves at any depth of an elastic semi-infinite space was derived. The results of this method agreed well with those of the conventional simplified method used to estimate seismic dynamic stress in soil dynamics when the incident angle of SV-wave was zero and the soil body stiffness was larger. The characteristics of the dynamic stress path due to oblique incidence of SV-waves were revealed. It was proved mathematically that the dynamic stresses due to oblique incidence of SV-waves form an oblique ellipse in a plane of two shear stress components( normal stress difference and horizontal shear stress). Sensitivity analysis of parameters was done. It was shown that incidence angle,Poisson's ratio,and depth/wave length are the basic factors affecting the dynamic stress path. The results laid a theoretical foundation for further studying site dynamic responses under oblique incidence of seismic waves.