基于数值模拟的截水帷幕渗透系数研究

Study on Permeability Coefficient of Cutoff Curtain Based on Numerical Simulation

渗透系数是截水帷幕设计关键参数之一,也是检验截水帷幕质量的主要指标。我国大多数规程规范中要求截水帷幕渗透系数应小于1.0×10^(-6)cm/s,但对这一数字的确定依据并不充分。基于MODFLOW软件开展了不同抽水量、不同帷幕墙渗透系数条件下共32个工况的数值模拟,研究了渗透系数对截水效果的影响。研究结果表明:渗透系数越小,帷幕墙截水效果越好;渗透系数为1.0×10^(-3)m/d时截水效果显著,继续减小渗透系数时截水效果提升并不明显;1.0×10^(-3)m/d可作为截水帷幕渗透系数设计依据,与规程规范中要求的1.0×10^(-6)cm/s(0.864×10^(-3)m/d)基本相符。采用围井抽水试验计算了某截水帷幕的渗透系数,检验了截水帷幕质量。研究结果为截水帷幕渗透系数的确定提供了理论依据。

Permeability coefficient is one of the key parameters in the design of cutoff curtain, and it is also the main index to check the quality of cutoff curtain. In most regulations of our country, the permeability coefficient of cutoff curtain is required to be less than 1.0 ×10^(-6) cm/s, but the basis for determining this figure is not sufficient. Based on MODFLOW software, the numerical simulation of 32 working conditions with different pumping volume and permeability coefficient of curtain wall was carried out, and the influence of permeability coefficient on water interception effect was studied. The results show that: the smaller the permeability coefficient is, the better the water interception effect of cutoff curtain is;when the permeability coefficient is 1.0 ×10^(-3) m/d, the water interception effect is significant, and the improvement of water interception effect is not obvious when the permeability coefficient continues to be reduced;1.0×10^(-3)m/d can be used as the design basis for the permeability coefficient of cutoff curtain, which is basically consistent with the requirement of 1.0×10^(-6) cm/s(0.864×10^(-3) m/d) in the regulations. The permeability coefficient of a cutoff curtain is calculated by surrounding well test and the quality is tested. The results provide a theoretical basis for the determination of the permeability coefficient of the cutoff curtain.