基于模量逐步软化的真拟静力永久变形计算方法
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摘要
基于地震整体变形分析原理,针对传统的等效节点力法和软化模量法无法全面考虑土体在地震荷载作用下的软化效应和体积收缩特性等问题,提出了一种较适合高心墙堆石坝的永久变形计算方法.该方法在动力时程分析中重点考虑了逐渐累积的残余剪应变和残余体应变对应力应变关系的软化效应,同时考虑了各时段残余振动孔压引起的最大动剪切模量的衰减效应.算例分析表明,考虑模量逐步软化的拟静力永久变形计算方法既可以较为真实地模拟地震实际情形,又能够得到坝体各部分永久变形的发展和累积过程.
A simplified procedure for evaluating seismic stability of high core type rock-fill dam subjected to earthquake shaking,in which the integrated effect of equivalent nodal force and step-by-step gradually softening modulus is taken into account,is presented based on whole earthquake deformation analysis.The fundamental feature of this procedure is the modified relationship of stress and strain by residual shear strain potential and residual volumetric strain potential in dynamic time-history analysis.In the meanwhile,the effect of the residual dynamic pore water pressure on the maximum shear modulus is considered.The numerical computations are performed by using the proposed method.It is shown that the time-history accumulative permanent displacement for a given core dam,in which earthquake effect is properly considered,is more rational compared with the conventional computational results.
A simplified procedure for evaluating seismic stability of high core type rock-fill dam subjected to earthquake shaking,in which the integrated effect of equivalent nodal force and step-by-step gradually softening modulus is taken into account,is presented based on whole earthquake deformation analysis.The fundamental feature of this procedure is the modified relationship of stress and strain by residual shear strain potential and residual volumetric strain potential in dynamic time-history analysis.In the meanwhile,the effect of the residual dynamic pore water pressure on the maximum shear modulus is considered.The numerical computations are performed by using the proposed method.It is shown that the time-history accumulative permanent displacement for a given core dam,in which earthquake effect is properly considered,is more rational compared with the conventional computational results.
引文
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[8]王玲玲,何蕴龙,费文平.水牛家心墙堆石坝地震永久变形及液化分析[J].岩土力学,2004,25(1):165-168
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[2]MAKDISI F I,SEED H B.Simplified procedure forestimation dam and embankment earthquake induceddeformations[J].J Geotech Eng Div,ASCE,1978,104(GT7):849-868
[3]迟世春,林皋,孔宪京.堆石坝残余体应变对计算面板堆石坝永久变形的影响[J].水力发电学报,1998(1):59-67
[4]刘汉龙,陆兆溱,钱家欢.土石坝地震永久变形分析[J].河海大学学报,1996,24(1):91-96
[5]KUWANO J,ISHIHARA K.Analysis of permanentdeformation of earth dams due to earthquakes[J].Soils and Foundations,1988,28(1):41-55
[6]沈珠江,徐刚.堆石料的动力变形特性[J].水利水电科学研究,1996(6):143-150
[7]HYDE A F L,WARD S J.A pore pressure andstability model for a silty clay under repeated loading[J].Geotechnique,1985,35(2):113-125
[8]王玲玲,何蕴龙,费文平.水牛家心墙堆石坝地震永久变形及液化分析[J].岩土力学,2004,25(1):165-168
[9]汪闻韶,金崇磐,王克成.土石坝的抗震计算和模型试验及原形观测综合报告[J].水利学报:土动力学专辑,1987(12):1-15
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