关联帷幕防渗性能变化的重力坝结构稳定评价方法

Evaluation Method of Gravity Dam Structural Stability Related to the Performance Change of Impervious Curtain

坝基防渗帷幕对重力坝稳定起着至关重要的作用,随着水库大坝运行时间的增长,在高水头渗透甚至是库水化学侵蚀作用下,帷幕防渗性能会逐渐衰弱和退化。常规的方法从力学角度,按有、无防渗帷幕情况根据经验取折减系数计入扬压力,进行结构稳定计算,此方法适用于新建重力坝,但无法定量考虑帷幕防渗性能变化对建成运行后重力坝结构稳定的影响。为了更合理的评价其影响,通过有限元数值计算分析,建立重力坝结构稳定及应力与防渗帷幕渗透系数的关系,提出一种关联帷幕防渗性能变化的重力坝结构稳定评价方法,可定量评判帷幕防渗性能衰减对大坝稳定的影响。

The impervious curtain of the dam foundation plays an important role in the stability of the gravity dam.With the increase of the reservoir dam operation time,under the influence of high water head penetration and even chemical erosion of reservoir water,the curtain impervious performance will gradually weaken and degrade.The conventional method is purely from the mechanical point of view.It can only empirically take the reduction coefficient into the uplift pressure based on whether there is impervious curtain or not to calculate the structural stability coefficient,this method is suitable for new gravity dam,however it cannot quantitatively consider the influence of curtain impervious performance change on structural stability of completed and operational dam.In order to evaluate its impacts more reasonably,this paper establishes the relationship between the structural stability of the gravity dam and the permeability coefficient of the impervious curtain through finite element numerical calculation and analysis,and proposed a method for evaluating the structural stability of gravity dam which is related to the performance change of impervious curtain,which can be used to quantitatively evaluate the influence of the curtain impervious attenuation on the dam stability.