岩石单结构面剪切变形渗透性演化规律

Seepage evolution of shear deformation for a single rock structure surface

为了研究剪切作用下单裂隙渗透性的演化规律,在Comsol中采用Weierstrass随机分形函数来生成单裂隙,调整2个裂隙面的相对位移来模拟剪切作用,通过分析不同剪切位移条件下裂隙隙宽的变化以及不同流量下的非线性效应发生的界定范围,并绘制散点图与函数曲线拟合确定剪切过程影响裂隙渗透率的因素,给出定量关系。结果表明:未发生剪切时,隙宽的概率密度分布满足标准的高斯分布,而随着剪切过程的发生,隙宽的高斯分布被破坏,仅体现标准高斯分布的部分特征;发生剪切时,渗透率先有一个减小的过程,然后在一定范围内波动;当Re>9.6时,流体开始从线性向非线性发展。对岩石单结构面剪切变形过程中裂隙孔径变化对流体渗流特性的影响进行模拟,可为分析地质体中结构面变形对地热变化的影响提供参考。

In order to study the evolution of fracture permeability under shear action,a Weierstrass random fractal function was used in Comsol to generate a single fracture,and the relative displacements of two fracture surfaces were adjusted to simulate shear action.Changes of fracture width under different shear displacements and the defined range of nonlinear effects under different flow rates were analyzed,the factors affecting fracture permeability in shear process were determined by using scatter plot and function curve fitting,and the quantitative relationship was given.The results show that the probability density distribution of the gap width meets the standard Gaussian distribution without shearing,but with the shearing process,the Gaussian distribution of the gap width is destroyed and only reflects parts of the characteristics of the standard Gaussian distribution.When the shear occurs,the permeability first has a decreasing process,and then fluctuate within a certain range.The smaller aperture is unfavorable to the water flow through near the contact area.When Re>9.6,the fluid begins to develop from linear to nonlinear.The influence of fracture aperture on fluid seepage characteristics during shear deformation of single fracture of rock is simulated,which provides some reference for analyzing the geothermal change caused by fracture deformation in geological bodies.