Experimental Research on Threshold Values of Deformation Failure of Rock Discontinuities with Different Roughness Under Cyclic Loading and Unloading
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摘要: 岩石的应力"门槛值"是预测是否发生变形破坏的重要参数。为研究应力"门槛值"的变化规律及其对岩石变形特征的影响,利用CSS-1950岩石双轴流变试验机对不同粗糙度的Barton曲线结构面的水泥砂浆试块展开分级循环加-卸载试验。通过分析各法向应力下不同结构面试样的变形特征,总结"门槛值"的求解方法。基于"门槛值"的计算结果,分析了"门槛值"与岩石节理粗糙度系数(JRC)和法向应力的关系,探讨了JRC和法向应力对结构面变形特征的影响。研究表明:随着剪切荷载等级的提高,结构面循环加载后的位移先呈现线性增长,而后进入非线性发展阶段,两者转折点所对应的水平应力值即为结构面的"门槛值";随着JRC或法向应力的增大,结构面的"门槛值"增大,"门槛值比率"却发生了下降。Abstract: The threshold value of rock is an important parameter to predict whether deformation failure occurs. To study the changing law of threshold value and its influence on rock deformation characteristics, using the CSS-1950 biaxially rheological testing machine for rock to conduct the cyclic loading and unloading test for cement mortar blocks with different roughness of Barton curve discontinuities, by analyzing the deformation characteristics of different rock discontinuities specimens under various normal stresses, the solution method of threshold value was summarized. Based on the calculation results of threshold values, the relation between the threshold value, the joint roughness coefficient (JRC) and the normal stress was analyzed. The effects of the JRC and the normal stress on the deformation characteristics of rock discontinuities were discussed. Research showed that with the increase of the shear load level, the displacement of the rock discontinuity subjected to cyclic loading first grew in a linear trend, and then grew in a nonlinear development state. The horizontal stress values corresponding to the two turning points were the threshold values of the rock discontinuity. With the increase of the JRC or normal stress, the threshold values of the rock discontinuity increased, however the threshold value ratio decreased.
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Key words:
- rock discontinuity /
- roughness /
- cyclic shear loading /
- deformation characteristics /
- threshold value
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