西部某水电站覆盖层地基离心机动力试验数值模拟

Dynamic Numerical Analysis of a Centrifuge Model Test for Overburden Foundation

地震荷载作用下深厚覆盖层地基模量和强度会因孔隙水压力上升发生弱化,其会导致地基发生较大的变形进而影响高土石坝的坝基-坝体防渗体系稳定和安全,甚至会引发大坝溃决造成重大损失。本文应用大连理工大学自主研发的岩土工程高性能非线性有限元分析软件GEODYNA和静动统一实用化弹塑性本构模型,对西部某水电站覆盖层地基离心机试验进行了动力弹塑性有效应力数值分析,研究了地震条件下覆盖层地基加速度响应及孔压发展情况,并与试验进行了对比。结果表明:计算和实测加速度幅值大小变化规律吻合较好;计算孔隙水压力随地震时间变化的幅值大小与实测数据基本一致。研究成果验证了开发的本构模型和软件的合理性和可靠性,可为覆盖层上高土石坝地震安全评价提供有效的数值分析工具。

The modulus and strength of the deep overburden foundation under earthquake load will be weakened due to the rise the of pore pressure,which will lead to great deformation thereby affecting the stability and safety of the foundation-dam impervious structures and even may cause significant losses as the dam burst.In this paper,the independently developed nonlinear finite element calculation software of GEODYNA by Dalian University of Technology with the practical static-dynamic unified elastic-plastic constitutive model was used to conduct a dynamic elastic-plastic effective stress analysis on a centrifuge test of an overburden foundation,and the acceleration response and the pore pressure under earthquake were analyzed and compared with the tests.The results show that the computed acceleration amplitude by the numerical method in the underside of the sand layer is basically consistent with the measured data.The computed trend and amplitude of the pore pressure with seismic time are basically consistent with the measured data.The research results have verified the rationality and reliability of the developed constitutive model and software program,and can provide an effective and credible numerical tool for the seismic safety evaluation of the high rockfill dam with deep overburden.