无限深透水坝基上悬挂式防渗墙控渗试验研究

无限深透水地基上巨厚覆盖层的渗流控制是大坝建设成败的关键问题之一。悬挂式防渗墙已在许多此类工程中使用,但其控渗效果和渗流机理的分析研究仍未达成共识。为了进一步研究悬挂式防渗墙的渗流机理和控渗效果,应用无限单元和有限单元结合法来模拟无限深透水地基,分析不同渗透系数、防渗墙深度和水头差时坝基渗流量和渗透坡降的变化规律,拟合出精度较高计算式,并通过渗流槽模型试验进行了验证。分析研究发现,悬挂式防渗墙在控制无限深透水地基渗透坡降方面效果明显,能有效遏制渗透破坏;在控制渗流量方面,悬挂式防渗墙深度越大效果越明显,但需要辅助措施联合控制才能实现经济合理、技术可行的目标。分析研究结果有利于进一步认清悬挂式防渗墙的控渗规律。

Experimental studies on seepage control of suspended cut-off wall on infinite deep pervious foundation

Seepage control of foundation with the deep overburden layer which can be considered as the infinite deep pervious foundation is one of the key problems that determines the success or failure of dams construction. The suspended cut-off wall has been used as the anti-seepage structure in the same projects, but analysis of its seepage control effects and percolation mechanism has no common understanding in the theory. In order to make deep studies of the seepage control effects and percolation mechanism of the suspended cut-off wall, a model in combination with the infinite element method is established to simulate the infinite deep pervious foundation, analyzing the variation in seepage discharge and seepage gradients under the conditions of different permeability coefficients k, depth of the cut-off wall s and the water head difference ΔH, and fitting out the calculation formulas having high accuracy. The verification tests have been done in those studies. And the experimental study results show that the calculation formulas are right. From those studies it is found that the seepage control impacts of the cut-off wall are more significant than the infinite deep pervious foundation in controlling the seepage gradients, and the cut-off wall can effectively control seepage-induced damages; and in controlling seepage discharge, the greater the depth of the cut-off wall is, the more significant the effect is, but it needs auxiliary measures to realize reasonable goals in economy and technology. The analysis results of the studies are helpful to further understanding of the seepage control principles of the suspended cut-off wall.