深厚覆盖层上高心墙堆石坝新型结构抗震安全性研究

Study of Seismic Safety of New Structure for High Rockfill Dam with Earth Core on Deep Overburden

建设在深厚覆盖层上的高心墙堆石坝防渗体系通用采用心墙—廊道—防渗墙结构型式,为了进一步缩短工期及节省投资,提出一种新型结构型式,即在坝基面处挖除表层部分覆盖层,浇筑混凝土盖板,在盖板内部设置廊道,以便在坝体填筑的同时进行防渗墙施工。为评价这种新型结构的抗震安全性,依托我国西部某水电工程,采用动力有限元法研究了大坝的动力响应特性。计算结果表明,由于坝基覆盖层的影响,大坝在地震过程中的加速度响应较小,顺河向最大加速度为0.34g,防渗墙与盖板的动应力均在强度允许值范围之内,大坝震后沉陷量约占坝高的0.34%,且坝坡在地震过程中处于稳定状态。因此分析认为该深厚覆盖层上高心墙堆石坝新型结构在该地震波作用下具有足够的抗震安全性,具有一定的应用前景。

The anti-seepage system for high rockfill dam with earth core built on deep overburden,is usually composed by the core wall,corridor,and diaphragm wall. In order to shorten the construction period and save investment,a new structure for rockfill dam with earth core on deep overburden is proposed. Partial overburden should be excavated firstly,then pouring concrete cover,a corridor is reserved in this concrete cover,which makes the construction of diaphragm wall easier. A case study on seismic safety of a high rockfill dam with earth core,which is built in west area of China,is carried out by means of dynamic finite element method. The results indicated that the response of the dam during earthquake is not very significant because of the effect of deep overburden. The maximum horizontal acceleration of the dam is 0.34 g. The dynamic stresses of the diaphragm wall and concrete cover are within the allowable value of strength. The biggest settlement of the earthquake permanent deformation is 0.34% of the maximum dam height. And the dam slopes are stable during the earthquake. Consequently,the new structure for rockfill dam with earth core on deep overburden is safety during the earthquake,and can be widely used in the future.