坝基渗流与坝肩绕渗实用计算方法探讨

Discussion on Computing Method of Dam Foundation Seepage and Bypass Seepage of Dam Abutment

基于复变函数的保角映射理论及数值分析法,推导了坝基二维渗流模型解析解,通过数值分析软件给出了无防渗帷幕、有防渗帷幕时坝基单宽渗漏量计算公式及基底扬压力计算公式,并以重力坝为例分析了防渗帷幕深度,认为当防渗帷幕深度超过1倍的坝底宽时,随着防渗帷幕深度的增加对扬压力的抑制作用不明显;且相同深度防渗帷幕时透水层厚度越小基底扬压力反而相对越大,但当透水层厚度接近帷幕深度时(即小于1.35倍帷幕深)基底扬压力又开始逐渐减小即呈现"关门现象"。同时基于积分理论推导了无防渗帷幕时坝肩绕渗渗漏量解析计算公式,最后通过工程实例与有限元法计算结果进行比较,验证了该解析计算公式精度可靠、方便快捷。

Based on the theory of conformal mapping in complex function and numerical analysis method,the analytic solution of two-dimensional seepage model of dam foundation is derived.Based on the numerical analysis software,the calculation formula of leakage per unit width of dam foundation and basement uplift pressure are given with and without anti-seepage curtain.Taking gravity dam for an example,the impervious curtain depth is analyzed.The restraining effect of uplift pressure is not obvious when the depth of the impervious curtain is greater than the dam bottom width.Under the same depth impervious curtain,the basement uplift pressure increases with the pervious layer thickness reduces.When the thickness of permeable layer approaches the depth of curtain,the basement uplift pressure begins to decrease gradually.It appears the phenomenon of＂closing door＂.The analytic formula of the amount of leakage bypass seepage of dam abutment without anti-seepage curtain is given by integration theory.By compared engineering examples and the results obtained by finite element method,it demonstrates that the calculation method is convenient and it has reliable accuracy.