一例由蓄水诱发的库岸边坡变形

Impounding-Induced Deformation of Reservoir Banks, A Case History

加拿大Oldman坝的库岸边坡主要由近水平、互层的砂岩及泥岩构成 ,自 1993年开始蓄水以来库岸边坡一直处于变形之中。文章在简介区域地质条件、工程地质条件和水库蓄水诱发变形的基础上 ,对变形诱发机制进行了讨论。基于监测资料分析 :(1)由于水库库岸边坡的卸荷裂隙十分发育 ,提供了快速的水力通道 ,蓄水期水对库岸边坡稳定存在不利影响 ;(2 )该例的泥岩不存在膨胀性 ;(3)库岸边坡变形是由于水的快速渗透导致有效应力降低和泥岩软化 ,库岸边坡应力重新调整引起的 ;(4 )对于软岩边坡 。

The banks of the Oldman Dam Reservoir in Canada are mainly composed of sub-horizontally interbedded sandstones and mudstones and have been deformed since the first impounding in 1993.In this paper,regional geology,engineering geology and impounding-induced deformations of the banks are briefly described,and then discussions are made on the deformation mechanism.Based on the anlysis of the monitored data,(1)during the first impounding stage,water has adverse effect on the bank stability due to the highly developed unloading joints in the bank,which provides a rapid channel for the water infiltration;(2)the mudstones are not expansive in this case;(3)the bank deformation is caused by the reduction of effective stress,the softening of mudstone and the corresponding stress adjustment in the bank due to the rapid water infiltration;(4)deformation stability is more important than the strength stability for slopes in the soft rock,especially for the reservoir banks in the soft rock.