反滤层对高心墙堆石坝拱效应影响研究

心墙与坝壳间不均匀沉降可导致心墙内产生拱效应,反滤层变形模量高于相邻的心墙料及过渡料致使拱效应强烈,分析心墙拱效应并通过合理措施降低其影响极为重要。以某心墙堆石坝为例,采用有限元法计算了反滤料变形模量及反滤层新结构对坝体应力应变及心墙拱效应的影响。计算结果表明:采用低变形模量反滤料或在反滤层内分级填筑高塑性黏土,均可增加反滤层沉降,有效减小沉降差,削减拱效应。心墙的沉降差、应力变化率、拱效应强弱呈现较高的一致性,皆在1/2坝高附近最大。拱效应系数最小值随反滤料变形模量降低而增大。内部填筑黏土可使反滤料最大沉降增加0.47 m,使心墙拱效应系数最小值提升至0.683,相当于反滤料变形模量降低25%时的模拟结果。因施工时难以获取低变形模量反滤材料,故提出的反滤层改善结构具有较高的工程应用价值。

Influence from filter layer on arching effect of high rockfill dam with core wall

The uneven settlement between core wall and dam shell can cause arching effect inside of core wall， while if the deformation modulus of filter layer is higher than those of the core material and the transitional material， the arching effect can be more intensified. Thus， it is quite important to analyze the arching effect of core wall and reduce its impact through the relevant reasonable measures. By taking a rockfill dam with core wall as the study case， the impacts from both the deformation modulus of the filtering material and the new structure of the filter layer on the stress strain of the dam body are analyzed herein with the finite element method. The result shows that the settlement of the filtering material can be increased by adopting the filtering material with lower deformation modulus or filling high plastic clay in steps inside of the filter layer， from which the settlement difference can be effectively decreased and then the arching effect can be reduced as well. Meanwhile， the settlement difference， the stress variation rate and the intensity of the arching effect of the core wall present higher coincidence and all of them reach to the maximums at 1/2 of the dam body. The minimum value of the coefficient of the arching effect is to be increased along with the decrease of the deformation modulus of the filtering material. Moreover， the inside filling of clay can make the maximum settlement of the filtering material increased by 0.47 m and the minimum value of the coefficient of the arching effect of the core wall increased to 0.683， which correspond with the simulated results obtained when the deformation modulus of the filtering material is decreased by 25%. Because it is difficult to get the filtering material with lower deformation modulus during the construction， thus the improved structure proposed herein has a higher engineering application value.