某水利枢纽厂房大型基坑开挖渗流研究

Research on seepage of large foundation pit excavation of a hydro-junction power plant

渗流,特别涉及到自由面或浸润线的确定是岩土工程的重点和难点问题。借鉴砂土坝的渗流分析方法,采用经典分段组合法理论得到基坑开挖边坡渗流简化模型Ⅰ。在此基础上将土层分层,应用土层分界面上的渗流折射定律,得到简化模型Ⅱ。分别求解两种模型得到正常水位和最大水位条件下的渗水量,与工程实际的渗水量进行对比发现,计算渗水量大于实际渗水量,这是由于忽略了围堰对渗水的阻隔作用。在正常水位条件下,模型Ⅱ的结果优于模型Ⅰ。

Seepage problem, especially involves free surface or saturation line, is a major and difficult problem in rock and soil engineering. Borrowing ideas of seepage analysis methods from sandy soil dam, and using classical subsection-combination method, simplified model I is obtained for analyzing seepage of foundation pit. Considering the effect of soil strata and using seepage refraction at the interface between two different soils, model Ⅱ is obtained on the basis of model Ⅰ. Seepage discharge is calculated respectively by solving the two models under the condition of normal and maximum water levels. Then comparing it with actual seepage discharge, discovered that the result of model Ⅱ is better than that of model Ⅰin the condition of normal water level; and the seepage discharges of two models are less than that in engineering in the condition of maximum water level because of ignoring the impediment effect of cofferdam on groundwater.