高心墙堆石坝接触黏土与混凝土基座接触特性研究

Influence of Contact Effect between Contact Clay and Concrete Cushion on Behaviors of High Earth Core Rockfill Dam

高心墙堆石坝心墙底部与岸坡之间通常设置高塑性黏土简称接触黏土,以提高心墙与岸坡接触面附近土体抗剪切变形能力,接触黏土变形特性对高心墙堆石坝防渗体工作性态具有重要影响。以四川LHK 295 m级高心墙堆石坝为依托工程,进行了接触黏土与混凝土的接触面剪切试验,探究LHK坝接触黏土与混凝土基座接触面剪切特性的影响因素。试验结果表明,含水率和法向应力是接触面剪切特性的重要影响因素,接触面随法向应力的增大表现出2种破坏模式,其抗剪强度可用双线型Mohr-Coulomb强度准则表示;接触面应力应变关系可用双曲线较好描述,其体积应变可采用分段函数描述,并以此建立了一个接触黏土与混凝土非线性弹性本构模型,将该模型嵌入有限元程序,应用于LHK心墙堆石坝接触黏土与混凝土垫层的接触分析,三维有限元计算结果表明,接触黏土层切向位移沿接触黏土厚度方向自上至下逐渐减小,方向均指向河谷,符合接触黏土层滑移的基本规律,可为高心墙堆石坝计算提供参考。

Referred as contact clay,high plastic clay is usually set between the earth core and the bank slope to improve the shear deformation ability of high earth core rockfill dam.The shear behavior of contact clay has an important influence on the impermeable body working behavior.In this study,based on the 295 m grade LHK high earth core rockfill dam in Sichuan province,a series of direct shear tests between contact clay and concrete cushion are carried out to study the shear behavior of contact clay-concrete cushion interface of LHK dam.Results show that water content and normal stress are significant factors affecting the shear behavior of interface.The interface exhibits mainly two kinds of shear failure modes with the increase of normal stress,and the shear strength can be formulated by bifold-line type Mohr-Coulomb strength criterion.It is also found that the stress-strain relationship can be described by hyperbolic curve,and the volumetric strain can be described by subsection function,a nonlinear elastic constitutive model is constructed for the contact between clay and concrete which is fitted in the finite element program and applies on the contact analysis between contact clay and concrete cushion of LHK dam.The finite element analysis result show that tangential displacements of contact clay gradually decreases along the thickness and pointing to the valley.These are in accordance with the sliding law of contact clay,which provide a favorable reference to deformations calculation of high earth core rockfill dam.