深覆盖层上面板堆石坝防渗墙应力变形分析

采用三维非线性有限元方法分析深覆盖层上面板堆石坝防渗墙应力变形特性,覆盖层和坝体材料的本构关系采用邓肯-张E-B模型,在防渗墙和覆盖层之间设置接触摩擦单元以模拟两者之间的相互作用。通过建立的有限元模型分析了坝体分期筑坝、坝体填筑速度以及防渗墙施工顺序对墙体应力变形特性的影响,同时探讨悬挂式防渗墙的应力变形特性。计算结果表明:坝体分期填筑对防渗墙的应力变形特性影响较小;较快的施工速度将引起坝体竣工期防渗墙较大的应力变形,其中拉应力达到3 MPa,顺河向变形达到15 cm;防渗墙靠后的施工顺序可以使运行期防渗墙拉应力减小2.42 MPa,顺河向变形减小达85%;悬挂式防渗墙贯入深度越小,其应力变形特性越趋于安全稳定。

Stress and Deformation of Cut-off Wall of Concrete Faced Rockfill Dam Built on Deep Overburden Foundation

Three-dimensional finite element method is used to analyze the stress and deformation behavior of cut-off wall of concrete faced rockfill dam on deep overburden foundation.The Duncan-Chang E-B model is used to simu-late the constitutive relationship between rockfill and overburden material.The contact friction elements are set to simulate the interaction between the concrete structures and the overburden and cushion materials.The influences of staged-filling scheme,construction rate of dam body and construction sequence on stress-deformation behavior of the cut-off wall are discussed.In addition,the stress-deformation behavior of the suspended cut-off wall is also ana-lyzed.Based on the numerical analysis,it is concluded that the staged-filling of dam body has small impact on the stress and deformation of the cut-off wall,whereas high construction rate may cause large stresses and displacements of the wall during completion period (tensile stress reaches 3MPa,deformation along the river direction amounts to 1 5cm),and the sequence of constructing cut-off wall in later stage could reduce the tensile stress by 2.42MPa and the deformation along river direction by 85%.A small depth of suspended cut-off wall could also improve its stress and deformation behavior.