深埋隧洞涌水预测非达西流模型及数值模拟

NON-DARCY FLOW MODEL AND NUMERICAL SIMULATION FOR PREDICTING WATER INFLOW IN DEEP TUNNEL

由于深部岩体具有高温、高地应力、高地下水压等特点,深埋隧洞开挖必然会带来高水力梯度引起的控水断裂高流速非达西流问题。基于单裂隙高流速非达西流试验结果,建立二次型的非达西流本构模型,及非达西流影响系数与渗透率的关系式。通过构建统一的达西–非达西流本构方程,建立达西–非达西流有限元分析方法,采用共轭梯度迭代法,进行非达西流有限元方程的迭代求解。最后将理论与方法应用于深埋隧洞的涌水预测中。通过对比达西与非达西流结果表明,对于裂隙宽度较大情况,采用非达西流理论计算是十分必要的,且断层(发育溶蚀裂隙)的宽度及多条断层的交叉位置等对隧道涌水量具有较大的影响。

The constitutive model of non-Darcy flow was established based on the laboratory data of high velocity non-Darcy flow through a single smooth parallel-plate fracture, and the determination method of non-Darcy flow influence coefficient was introduced. Generalized constitutive equation for both Darcy and non-Darcy flows was developed. The finite element method based on the generalized Darcy and non-Darcy flows constitutive equation was presented; and the basic iteration steps of non-Darcy flow analysis were performed according to conjugate gradient iterative method. Finally, the above theory and method were applied to the prediction of water inflow in a tunnel. By comparison of the two different calculation results for Darcy and non-Darcy flow theories, the necessity of adopting non-Darcy flow theory was explained. It is also found that the aperture of a big fracture and location of cross point of multiple faults have considerable influences on water inflow in the tunnel.