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Seismic wave input method for high earth dams considering the transmission amplification effect of the bedrock–overburden interface
Computers and Geotechnics ( IF 5.3 ) Pub Date : 2021-02-01 , DOI: 10.1016/j.compgeo.2020.103927
Fei Wang , Zhiqiang Song , Yunhe Liu , Bohua Luo

Abstract The method for determining the input ground motion of concrete and earth dams on bedrock is not applicable to earth dams on overburden soil due to the transmission amplification effect of the seismic waves at the bedrock–overburden interface. Moreover, the free-field and artificial boundary parameters of the overburden foundation cannot be calculated using analytical methods because of the nonlinear characteristics of the soil under strong earthquakes. Therefore, the nonlinear variations in the artificial boundary parameters and the equivalent load with the dynamic shear strain of the soil must be considered. First, the influencing factors of the transmission amplification effect under different types of waves are analyzed. Second, a method for determining the input ground motion with consideration of the transmission amplification effect is developed. Then, the free-field response at the truncation boundary of the overburden soil is obtained on the basis of the shear box model. The equivalent nonlinear viscoelastic artificial boundary element attached to the boundary soil element of the overburden foundation is generated; the stiffness and damping matrix of the viscoelastic artificial boundary element change with the shear strain of the boundary soil element. Subsequently, a nonlinear wave input method suitable for overburden foundations is established. Finally, the error degrees of the seismic response of the overburden foundation–dam system with respect to the far-field artificial boundary are compared using the methods of nonlinear wave input, fixed and free boundaries, and the viscoelastic boundary combined with the equivalent inertial force input. The efficiency and accuracy of the nonlinear wave input are high. The influence degree of the ground motion considering the transmission amplification effect on the response of the earth dam is also analyzed. Moreover, the influence mechanisms of the dynamic parameters of the overburden soil and bedrock on the transmission amplification effect and the seismic response of the overburden–dam system are discussed.

中文翻译:

考虑基岩-覆土界面传输放大效应的高土坝地震波输入法

摘要 由于地震波在基岩-覆盖层界面的传输放大效应,确定基岩上混凝土和土坝输入地震动的方法不适用于覆盖土上的土坝。此外,由于强地震下土壤的非线性特性,无法使用解析方法计算上覆地基的自由场和人工边界参数。因此,必须考虑人工边界参数的非线性变化和土体动态剪应变的等效载荷。首先,分析了不同类型波下传输放大效果的影响因素。第二,开发了一种考虑传输放大效应的输入地震动确定方法。然后,基于剪切箱模型获得上覆土截断边界处的自由场响应。生成贴附于上覆地基边界土元的等效非线性粘弹性人工边界元;粘弹性人工边界元的刚度和阻尼矩阵随着边界土元的剪应变而变化。随后,建立了一种适用于上覆地基的非线性波输入方法。最后,采用非线性波输入、固定边界和自由边界的方法,比较了上覆地基-坝系统地震响应相对于远场人工边界的误差程度,粘弹性边界结合等效惯性力输入。非线性波输入的效率和精度高。还分析了考虑传输放大效应的地震动对土坝响应的影响程度。此外,还讨论了上覆土和基岩动力参数对上覆土-坝系统传输放大效应和地震响应的影响机制。
更新日期:2021-02-01
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