【摘要】 对于土石坝的地震永久变形,本文提出等效结点力-逐步软化有限元计算模型。首先根据坝体地震动力响应的非线性有限元分析确定各时段坝体单元可能发生的残余应变、振动孔隙水压力增量及累积振动孔隙水压力,以此对静变形模量和强度及静应力-应变关系进行修正,并应用于下一时段计算中;同时基于所确定的与上一时段地震作用所产生的潜在残余应变增量和静应力-应变关系确定地震作用相应的等效结点力。在每一时段末根据上述所确定的等效结点力和应力-应变关系,运用整体有限元分析确定坝休的残余变形增量,将各个时段计算所确定的残余位移累加得到地震作用后坝体的残余变形量。这种方法能够同时考虑地震惯性力效应和土的软化效应对土石坝地震永久变形的影响。更多还原

【Abstract】 This paper presents a finite element procedure for evaluating seismically-induced permanent deformation of earth-rock dams.In the proposed procedure,both concepts of equivalent nodal forces and step-by-step gradually softening moduli are integrated together.The earthquake duration is divided into a certain number of time increments.And for each time increment the residual strain and dynamic pore water pressure which is likely induced during previous time increments under undrained condition are estimated on the basis of the stress condition obtained by the dynamic analysis and the empirical patterns of both residual strain and pore water pressure achieved experimentally.Then,the computed accumulative pore-water pressure at the end of each time increment is used directly to modify the static hyperbolic relationship between stress and strain which is to be used for the next time period.And at the same time,the equivalent nodal forces equivalent to incremental residual strain potential are defined.By using the modified stress-strain relationship,the incremental deformations are computed when the nodal forces equivalent to earthquake effect on the dam defined as above are imposed on the earth-rock dam.The computed incremental displacements of the earth-rock dam for each time increment are accumulated and the accumulative displacements can be regarded as approximation of the residual deformation which is to be initiated by earthquake shaking.In fact,the proposed numerical procedure has taken into consideration both the inertia effect and the softening effect of earthquake-induced loading on the permanent deformation of the earth-rock dam.更多还原