重力坝坝体及坝基不同渗透系数对坝基扬压力的影响研究

Analysis on Effects of Uplift Force during Different Permeability Coefficients of Concrete Dam and Its Fundation

建立在混凝土为透水材料的基础上,根据不同的防渗类型分别建立无帷幕无排水和有帷幕有排水的两种情况整体渗流分析模型,通过改变坝体和坝基的渗透系数及相对比值,利用有限元法进行稳定渗流分析,研究坝基扬压力的分布及大小,并与现行规范计算值比较。研究表明,考虑渗透系数之后坝基扬压力分布与规范建议值基本一致;在无帷幕、无排水的情况下,坝基扬压力随坝体与坝基岩体的渗透系数比值而变化,并沿建基面出现波动。在有帷幕、有排水的情况下,规范计算扬压力分布较按透水体计算结果偏小;坝基渗透系数越大,所得坝基各点扬压力与规范计算值越接近。

Based on assuming that the concrete is a kind of pervious material, two kinds of seepage analysis models are built to study the uplift force distribution law and its values along the dam foundation＇ s building surface with changes of the permeability coefficients of dam and foundation rock. The one model has the impervious curtain and drainage system, another has not. Through comparing the results from FEM model considered dam as pervious material with those calculated by the design code, it is showed that the uplift force distribution law from FEM model is coincide with that recommended by the design code. Under the condition of no impervious curtain and drainage system, the distribution value is varied with the ratio of permeability coefficient between the dam and foundation, and fluctuated along the dam foundation＇s building surface. Under the condition of existing impervious curtain and drainage system, the calculation value from the design code is less than that from FEM model. The difference would reduce with the increase of the foundation＇ s permeability coefficients