粘土岩饱和–非饱和渗流应力耦合模型及数值模拟研究

CONSTITUTIVE MODEL OF SATURATED-UNSATURATED CLAY AND ITS NUMERICAL SIMULATION

岩体中饱和–非饱和渗流、应力耦合行为对工程岩体的强度和稳定性有十分重要的影响。基于粘土岩实验室非饱和渗流试验的结果,将考虑塑性应变硬化的非饱和渗流、应力耦合模型、Hoek-Brown非饱和渗流、应力耦合模型应用于模拟某粘土岩竖井,研究其在开挖、通风、衬砌支护及长期运营期围岩内渗流从初始饱和→非饱和→近饱和的过程,以及竖井的非饱和流动区域大小对水力学参数(Biot固结系数、饱和度与毛细孔隙压力、水相的相对渗透系数与饱和度)的敏感性。结果表明:水力学参数对非饱和渗流的影响区域非常显著,尤其是水相的相对渗透系数与饱和度的关系。力学模型的差异对非饱和区的影响几乎可以忽略不计。

Based on laboratory data of unsaturated flow in clay, the constitutive model of unsaturated flow coupled model for clay considering plastic strain hardening and Hoek-Brown model is applied to simulate the swelling and shrinking behavior of clay shaft during excavation, concrete lining stage and long time ventilation. With the help of numerical simulation, the flow process in clay from initial saturated to desaturated and then to resaturated is stated. Furthermore, the sensitivity analysis of Biot coefficient, capillary pressure and water relative permeability with saturation degree is discussed; and the results show that the hydraulic parameters have effects on unsaturated zone in surrounding rock mass, especially the water relative permeability, while the mechanical behavior of clay has low effect on unsaturated flow law in surrounding rock mass.