剪切破坏过程中岩体单裂隙力学及非线性渗流特性试验研究

Experimental study on mechanical and nonlinear seepage ofsingle rock mass fracture with shear failure

裂隙岩体在复杂应力和渗流环境下的物理力学特性对库坝系统岩体稳定极为重要。为了厘清剪切-渗流耦合作用下的岩体裂隙力学及渗流特性,通过制作类岩试件开展了岩体单裂隙剪切-渗流耦合试验,分析了剪切过程中裂隙剪切强度、法向位移增量、剪胀角、FORCHHEIMER定律系数等参数的演化过程,以峰值剪切位移为分界点,基于PATTON强度公式以及峰后剪胀公式构建了全剪切强度计算公式。以FORCHHEIMER定律为基础阐明了高水压和剪切破坏共同作用下裂隙非线性渗流特性的演化过程,揭示了FORCHHEIMER定律线性项及非线性项系数的演化过程,建立了用于判断渗流流态的临界雷诺数计算公式。结果表明:剪切破坏产生的碎屑充填物对裂隙峰后剪切强度、剪胀角和渗流特性影响显著,构建的剪胀公式和剪切强度计算公式可确定任意时刻的裂隙剪切强度值和隙宽变化值;由于水流惯性力的影响高渗压作用下裂隙非线性渗流特性显著,剪切过程中FORCHHEIMER定律线性项及非线性项系数不断减小并趋于稳定,并且临界雷诺数在剪切过程中不断增大。

The stability of fractured rock mass is important for the operation of reservoir and dam system under complex stress and seepage condition.In order to clarify the fracture mechanics and seepage characteristics of rock mass with shear-seepage coupling,the shear-seepage coupling tests of single fracture were carried out by making rock-like specimens.The evolution law of the key parameters,including shear strength,increment of normal displacement,dilatancy angle and parameters of FORCHHEIMER's law,was analyzed;the peak shear displacement was set as the dividing point.The total shear strength calculation equation was established based on the PATTON's and proposed dilatancy equations.FORCHHEIMER's law was used to analyze the non-linear seepage characteristics of fracture,the evolution law of the linear and nonlinear term coefficients of FORCHHEIMER's was revealed,and the computational formula of critical Reynold's number was proposed to determine the seepage flow regime.The results show that the filling produced by shear failure has an obvious effect on the shear strength,dilatancy angle and non-linear seepage characteristics of fracture.The established shear strength and dilatancy equations can confirm the shear strength and aperture of fracture at any time.Due to the influence of inertia force,the nonlinear seepage characteristics of fracture under high hydraulic pressure are significant.The values of two coefficients of FORCHHEIMER's are decreased and Reynold's number is increased with increased shear displacement.