A Study on a Seismic Behavior of embedded Pipeline Under an Earthquake

本文研究了埋置管道在入射波作用下的三维东动力问题。入射波被认为是Ricker小波形式的平面SH波，其锋面倾斜于圆柱体的轴线。利用圆柱、边界层和带空腔的弹性介质的三维波动方程的解对这些问题进行了分析，以满足弹性介质、边界层和圆柱的边界条件。这些解很容易通过对空间坐标的三个方向和时间方向进行傅里-汉克尔变换得到。圆柱和弹性介质分别是管道和地面的模型。而边界层也是不同于圆柱体或管道周围弹性介质层的模型。对弹性介质、边界层和管道的弹性常数比的各种情况进行了数值计算；管道轴线与入射波方向之间的夹角；以及入射波的周期。计算结果以水平面径向位移图的形式给出，包括管道的直径平面；得到了管道内外表面切向应力分布图，结果表明：1)在短入射波周期内，弹性介质入射侧出现反射波，筒体内部出现较大的局部切向应力，但筒体的位移很小。2)当入射波周期较长，边界层弹性常数较大时，柱体的位移与入射波的位移基本一致，产生的总应力为柱体。

This study deal with a seismic behavior of an embedded pipeline subjected to incident wave as for a three dimensional easto-dynamic problem. The incident wave is taken to be a plane SH wave in the form of a Ricker wavelet whose front is slanting to the axis of the cylinder. These problems were analyzed by the use of solutions of three dimensional wave equations of a cylinder, a boundary layer and an elastic medium having a cavity, so as to satisfy the boundary conditions of the elastic medium, the boundary layer and the cylinder. These solutions are easily obtained by mean of Fourie-Hankel transforms with respect to three direction of space coodirates, and the time direction. The cylinder and the elastic medium are models of the pipeline and the ground respectively. And the boundary layer is also model of different layer from the cylinder or the elastic medium, surrounding the pipeline.The numerical caluclations are carried out for various cases of the eastic constant ratios for elastic medium, boundaty layer and pipe ; the angle between an axis of pipe and the direction of incident wave ; and the period of incident wave.The results are presented in the from of a radial displacement diagram of the horizontal plane, including the diametrical plane of pipe ; and a tangential stress distribution diagram to the inner and outer surface of the pipe and those results are as follows :1) At the short period of incident wave, the reflected waves appear in the incident side of elastic medium and the large local tangential stresses occur in the cylinder, but the displacements of cylinder are very small.2) At the long period of incident wave and in case of relatively large elastic constant of the boundary layer, the displacements of cylinder is almost same as the displacement of incident wave, and the overall stresses occur is the cylinder.