岩石节理剪切过程中应力与渗流特性的数值模拟

NUMERICAL SIMULATION OF STRESS AND SEEPAGE PROPERTIES OF ROCK JOINT DURING SHEARING PROCESSES

岩石节理剪切过程中应力与渗流特性受节理法向条件的影响很大。在岩石节理表面形状三维数值化表达的基础上,首先建立岩石节理剪切过程中力学与渗流的计算模型;接着,应用GIS技术,模拟分析不同法向条件(固定应力、固定刚度)下节理的剪切过程,获得节理剪切过程中应力与渗流特性的变化规律。结果表明,法向应力、裂隙张开度、渗透系数均随着剪切位移的增加而逐渐增加,整个剪切过程渗透系数增加了两个量级左右;而剪应力的变化却受法向条件的影响,剪应力在出现峰值后快速下降,而后固定应力条件下剪应力很快趋于一个稳定的值,而固定刚度条件下剪应力却又缓慢上升。

The stress and seepage properties are mainly decided by the geometry such as surface roughness and aperture of rock joints; meanwhile, the different boundary conditions such as initial normal stress and normal stiffness also affect the stress and seepage properties. By using GIS technique, a new geometrical model is developed to describe the surface roughness and the aperture of a rock joint quantitatively. Numerical programs for simulating shear process are coded based on mechanical and hydraulic models of a rock j oint; and then, the stress and seepage properties during the shearing processes are simulated and predicted by using GIS technique. The main results of this research show that during shear process, the normal stress, aperture of fracture and hydraulic conductivity increase gradually and reach to stable values at last under different boundary conditions as the shear displacement increases. The hydraulic conductivity increases with two orders. However, the shear stress leaps to a peak one at the first step and decreases quickly at the second step. And then, the shear stress under constant normal stress reaches a stable value soon, while the shear stress under constant normal stiffness increases slowly.