剪切速率对岩石节理强度特性的影响

不同剪切速率下岩体结构面的力学特性研究是进行岩质边坡动力反应分析的重要前提。基于Barton峰值抗剪强度理论和均方根一阶导数值法的节理粗糙度系数计算方法，对前人研究中关于定法向应力条件下不同剪切速率的岩石节理峰值抗剪强度的室内直剪试验结果进行整理与计算，探究剪切速率对岩石节理总摩擦角的影响规律，提出与速率相关的岩石节理峰值抗剪强度经验公式。结果表明:当剪切速率在0~0.8 mm·s^-1范围内时，岩石节理试样的总摩擦角随剪切速率的变化呈现负对数变化规律；对于均质性和各向同性较强的岩石节理随剪切速率的增大，总摩擦角呈现减小趋势，对于非均质性和各向异性较强的岩石节理随剪切速率的增大，总摩擦角呈现增大趋势，且后者总摩擦角增大幅度小于前者的减小幅度；岩石节理的物性和微观几何形态对总摩擦角随剪切速率的增加而变化的影响较大，节理面的物性主要影响总摩擦角随剪切速率增加呈现增大或减小的变化趋势，节理面的微观几何形态主要影响总摩擦角随剪切速率的变化幅值。

Effect of Shear Rate on the Strength Characteristics of Rock Joints

The study on mechanical characteristics of rock discontinuity under different shear rates is an important premise of rock slope dynamic response analysis. Based on Barton peak shear strength theory and root mean square first-order derivative method calculating joint roughness coefficient, the laboratory direct shear test results of peak shear strength of rock joint under different shear rates with constant normal stress in previous researches were calculated, the effects of shear rate on total friction angle of rock joint were discussed, and the empirical formula of peak shear strength of rock joint related to the shear rate was proposed. The results show that when the shear rates are 0-0.8 mm·s^-1, the total friction angles of rock joint samples vary in the form of negative logarithm with the variation of shear rate; the total friction angles of rock joints decrease with the increase of shear rate for rock joints with relative strong homogeneity and isotropy, and increase with the increase of shear rate for rock joints with relative strong heterogeneity and anisotropy, and the increase range of the latter is less than that of the former; the physical property and microscopic geometry of rock joints play an important effect on the variation of total friction angles with the increase of shear rate, the physical property of rock joints plays an important effect on the increase or decrease tendency of total friction angle, and the microscopic geometry of rock joints plays a significant effect on the variation range of total friction angle.