A note on near-field site amplification effects of ground motion from a radially inhomogeneous valley  

作　　者：Zhang Ning Gao Yufeng Wu Yongxin Zhang Fei 

机构地区：[1]Key Laboratory of Ministry of Education for Geomechanics and Embankment Engineering, Hohai University [2]College of Civil and Transportation Engineering, Hohai University

出　　处：《Earthquake Engineering and Engineering Vibration》2018年第4期707-718,共12页地震工程与工程振动（英文刊）

基　　金：Fundamental Research Funds for the Central Universities under Grant No.2018B14014;the National Natural Science Foundation of China under Grant No.51608172,41630638 and 51479050;the National Key Basic Research Program of China "973" Program under Grant No.2015CB057901;the National Key Research and Development Program of China under Grant No.2016YFC0800205;the Public Service Sector R&D Project of Ministry of Water Resource of China under Grant No.201501035-03;the 111 Projects under Grant No.B13024

摘　　要：To improve the understanding of the near-field soil and topographic amplification effects, an analytical solution by the authors for the scattering of plane SH waves by a radially inhomogeneous semi-cylindrical valley is extended to the case of a line source of cylindrical SH waves. Upon confirmation of its accuracy with past exact solutions for a homogeneous and an inhomogeneous semi-cylindrical valley under far-field plane SH waves, the extended solution is used to calculate the ground motion amplification factors for both the homogeneous and inhomogeneous valleys subjected to near-field waves. A comprehensive parametric study is conducted with respect to the location of the wave source, the dimensionless frequency of the incident waves, and the inhomogeneity degree of the covering soil layer. It is found that more amplifications and reductions of ground motions will occur within a certain range in and around the valley as the sources are located further. Consistent with the far-field case, it is confirmed that an increase of the degree of inhomogeneity of the covering soil layer generally amplifies the ground motions significantly.To improve the understanding of the near-field soil and topographic amplification effects, an analytical solution by the authors for the scattering of plane SH waves by a radially inhomogeneous semi-cylindrical valley is extended to the case of a line source of cylindrical SH waves. Upon confirmation of its accuracy with past exact solutions for a homogeneous and an inhomogeneous semi-cylindrical valley under far-field plane SH waves, the extended solution is used to calculate the ground motion amplification factors for both the homogeneous and inhomogeneous valleys subjected to near-field waves. A comprehensive parametric study is conducted with respect to the location of the wave source, the dimensionless frequency of the incident waves, and the inhomogeneity degree of the covering soil layer. It is found that more amplifications and reductions of ground motions will occur within a certain range in and around the valley as the sources are located further. Consistent with the far-field case, it is confirmed that an increase of the degree of inhomogeneity of the covering soil layer generally amplifies the ground motions significantly.

关 键 词：elastic SH-waves wave scattering and diffraction ground motion amplification VALLEY CANYON 

分 类 号：P315.9[天文地球—地震学]