基于设计地震动的斜入射波时程确定方法对土石坝地震响应的影响  

Effects of oblique incident wave time history determination method based on design ground motion on seismic response of earth-rock dam

作　　者：王飞[1] 宋志强[1] 刘云贺[1] 张剑峰 WANG Fei;SONG Zhiqiang;LIU Yunhe;ZHANG Jianfeng(State Key Laboratory of Eco-hydraulics in Northwest Arid Region,Xi’an University of Technology,Xi’an 710048,China;China Three-Gorge Projects Development Co.,Ltd.,Chengdu 610041,China)

机构地区：[1]西安理工大学省部共建西北旱区生态水利国家重点实验室,西安710048 [2]中国三峡建设管理有限公司,成都610041

出　　处：《振动与冲击》2021年第19期80-88,共9页Journal of Vibration and Shock

基　　金：国家自然科学基金重点项目(52039008);国家自然科学基金(51479165;51779208)。

摘　　要：基于设计地震动的斜入射波时程确定方法对土石坝的地震响应有显著影响,分析了斜入射P波和SV波时程按均质岩体在平坦地表水平向设计地震动1/2调幅,获得这种常用方法及其适用性。在P波和SV波组合斜入射前提下,考虑两者对半无限空间自由场的共同作用,建立了空间任意点自由场分量表达式,基于控制点自由场分量与设计地震动分量相同的原则,建立了入射波时程与入射角度的函数关系,提出了基于两向设计地震动的入射波时程确定方法。分析了在按垂直入射假定确定斜入射波时程时半无限空间地表自由场和基岩-覆盖层-土石坝系统地震响应相对于该方法的偏差。结果表明:在任意非垂直入射角度下,控制点自由场响应偏离设计地震动较严重,获得的土石坝坝顶加速度大小随入射角度变化规律包含地震动强度变化的贡献,不是设计地震动作用下的结果;该方法获得的地表自由场位移与设计地震动水平和竖直分量均吻合良好,能够正确反映斜入射角度引起的非一致运动,可以在保持设计地震动强度不变的前提下,分析斜入射角度对土石坝地震响应的影响。The oblique incident wave time history determination method based on design ground motion has significant influences on seismic response of earth-rock dam.Here,this common method and its applicability were analyzed to obtain time histories of oblique incident P and SV waves using 1/2 amplitude modulation of horizontal design ground motion of homogeneous rock body on flat ground surface.On the premise of oblique incidence combined P wave and SV wave,considering the joint action of the two waves on free field of semi-infinite space,the expression of free field response component at any point in the space was established.Based on the principle of free field response component of control point being the same as the design ground motion component,the functional relationship between time history of incident wave and incident angle was established.A method to determine time history of incident wave based on 2D design ground motion was proposed.The deviation between the ground surface free field response of semi-infinite space and seismic response of bed rock-overburden-earth rock dam system relative to the proposed method was analyzed when time history of oblique incident wave was determined according to the assumption of vertical incidence.The results showed that under any non-vertical incidence angle,free field response of control point deviates from design ground motion more seriously,and the change law of acceleration of earth rock dam crest with incidence angle contains the contribution of ground motion intensity variation,but it is not the result under action of design ground motion;the ground surface free field displacements obtained with the proposed method agree well with horizontal and vertical components of design ground motion,and can correctly reflect the non-uniform motion caused by oblique incidence angle;effects of oblique incidence angle on seismic response of earth rock dam can be analyzed on the premise of keeping design ground motion intensity unchanged.

关 键 词：斜入射波时程 设计地震动 自由场 土石坝 地震响应 

分 类 号：TV312[水利工程—水工结构工程]