水库库区渗漏的三维数值模拟及处理措施影响分析

3-D numerical simulation on leakage of a reservoir and analysis on effect of its treatment measure

某拟建的大型水库左岸分布深厚的第四系砂卵砾石层,几乎全部覆盖。本文采用三维有限元法对该库区进行渗流状态模拟分析,了解库区的渗流、渗漏状况,对影响渗漏的因素做敏感性分析。结果表明,形成稳定渗流场后,水库的年渗漏量约为2 000万-3 000万m3,坝下游河谷左岸表面有超过允许水力坡降的区域存在,宜采取反滤处理措施;砂卵砾石层渗透系数、左坝肩帷幕灌浆长度与水库渗漏量分别呈正、反比例关系,封闭式帷幕的渗透系数对水库渗漏影响显著;在库区做尽可能长的帷幕灌浆,对于减少水库渗漏、降低下游溢出水力坡降均有益,其最优长度需结合经济指标、工期等因素综合衡量。

On the left bank of a proposed reservoir,deep quaternary sandy gravel strata distribute almost all over there. A 3- D finite element method is adopted herein for simulating and analyzing the seepage status of the reservoir area,so as to find out the seepage and leakage status therein and make a sensitive analysis on the factors to impact the leakage. The result shows that the annual leakage is to be about 20 to 30 million m3 after the formation of stable seepage field. An area with the hydraulic gradient that exceeds the allowable value is there on the surface of the left bank of the downstream valley of the dam,for which the filtering treatment measure is better to be adopted. The relationships between permeability coefficient of the sandy gravel strata and the length of curtain grouting at the left abutment with the reservoir leakage present a direct proportion and an inverse proportion respectively,while the permeability coefficient of the orifice-closed grouting curtain has significant effect on the reservoir leakage. It is beneficial to reduce the reservoir leakage and lower the hydraulic gradient of the overflow at the downslope,if making the curtain grouting for the reservoir area as long as possible,for which the optimal length is necessary to be comprehensively determined in combination with the factors of economic index,construction period,etc.