降低高沥青混凝土心墙拉应力的措施研究

传统沥青混凝土心墙堆石坝中心墙和坝壳沿坝轴线方向均为直线型。心墙在水压力推动作用下产生指向下游的挠曲变形,心墙轴线伸长致使其内部产生拉应力,坝高越高,心墙产生拉裂缝的风险越大。本文基于心墙产生拉应力的机理,提出了两种新坝型(直坝曲心墙坝型和曲坝曲心墙坝型)的改善措施。借助有限元计算,研究了坝高和坝轴线长度对心墙挠曲变形和拉应力的影响,考察了新坝型的改善效果,表明坝高越高、坝轴线长度越长和岸坡坡比越大,心墙拉应力越大,新坝型对减小心墙拉应力具有良好的效果。通过施工技术、施工工期以及经济成本等方面的分析,表明新坝型可行,具有良好的应用前景。

Measures to reduce tensile stress in high asphalt concrete core walls

Traditional rockfill dams with an asphalt concrete core wall is featured with a linear shape of both the core wall and dam shell.The core wall is deflected by the horizontal pushing of water pressure,and its deflection deformation and the elongation of its axis may induce tensile stress.Generally,a higher dam may have a higher risk of tensile cracks developed in its core wall.In this study,we analyze the generation mechanism of tensile stress in a core wall,and develop two new dam types as improving measures-a straight dam with a curved core(SDCC)and a curved dam with a curved core(CDCC).Finite element analysis is used to examine the influences of dam height and dam axis length on the deflection deformation and tensile stress in the core wall and to investigate the improving effect of these two types.Results show that a greater dam height,longer dam axis,and larger bank slope ratio of a traditional dam lead to greater tensile stress in its core wall,and consequently a greater reduction in tensile stress if it is modified into either of the two suggested dam types.Analyses on construction technique,construction period,and economic cost show that the new types of rockfill dams are feasible and may have a good application prospect.