高心墙堆石坝接触黏土与岸坡接触特性的离心模型研究

Centrifugal model tests on contact characteristics of interface between contact clay and bank slope in high core rockfill dams

为了提高砾石土心墙与岸坡之间的变形协调性,高心墙堆石坝通常在心墙与岸坡之间设置高塑性黏土,统称为接触黏土,接触黏土的变形特性对高心墙的应力变形性状和心墙的安全性有重大影响。开展了4组接触黏土与岸坡接触面的局部离心模型试验,通过调整施加的上覆荷载大小来探讨原型坝体不同高程处的接触面剪切位移发展规律。基于理论分析,提出了一个计算接触黏土与岸坡接触面离心模型试验中边界效应影响范围的解析表达式,以确定接触面离心试验中试验模型的相似比尺。试验结果表明:在原型坝体的不同高程处,接触黏土与岸坡之间均会产生一定的剪切位移,但不会出现分离现象;接触黏土和砾质心墙土变形主要以竖向下沉为主,并且接触黏土与砾质心墙土之间的沉降等值线变化较为连续,未出现陡变情况,这说明接触黏土起到了很好地协调变形的作用,因此在进行高心墙堆石坝的结构安全性分析过程中应考虑接触黏土与岸坡的接触效应。

In order to improve the deformation coordination between core wall and bank slope,the high core rockfill dam is usually equipped with high plastic clay between the core wall and the bank slope,which is collectively referred to as the contact clay.The deformation characteristics of the contact clay have a great influence on the stress deformation characteristics of high core wall.Four groups of centrifugal model tests are carried out on the interface between the clay and the bank slope,and the shear displacement of interface at different elevations of prototype dam is discussed.Based on theoretical analysis,an analytical expression is proposed to calculate the boundary effects in the centrifugal model tests on the interface between the clay and the bank slope so as to determine the similar scale of test model.The results show that at different elevations of the prototype dam,the interface between the contact clay and the bank slope will generate shear displacement.The deformation of the contact clay and gravel core-wall soil is mainly vertical settlement,and the settlement contour between the contact clay and the gravel core-wall soil changes continuously without steep change,which indicates that the contact clay plays a good role in coordinating deformation.Therefore,the contact effects between the contact clay and the bank slope should be considered in the structural safety analysis of high core rockfill dams.