Dynamic evolution of shear rate-dependent behavior of rock discontinuity under shearing condition

Abstract

Rock blocks sliding along discontinuities can cause serious disasters, such as landslides, earthquakes, or rock bursts. The shear rate-dependent behavior is a typical time-dependent behavior of a rock discontinuity, and it is closely related to the stability of a rock block. To further study the shear rate-dependent behavior of rock discontinuities, shear tests with alternating shear rates (SASRs) were conducted on rock discontinuities with various surface morphologies. The dynamic evolution of the shear rate dependency was studied in detail based on the shear test results, and three stages were identified with respect to the shear stress and shear deformation states. The test results revealed that dynamic changes in shear stiffness and the energy storage abilities of the rock discontinuities occurred in relation to the shear rate-dependent behavior of crack growth, which increased with an increase in normal stress and/or the joint roughness coefficient. The stage of decreasing shear stiffness corresponded to a stage of noticeable shear rate-dependency, and the shear rate was found to have no influence on the initial crack stress. 岩石块体沿结构面滑动会引发严重的灾害, 如滑坡, 地震或岩爆等。结构面的剪切速率依存性是一种典型时效特性, 它与岩体的稳定性密切相关。为了深入研究结构面的剪切速率依存特性, 对多种表面形态各异的结构面开展了交替变换剪切速率的剪切试验, 对剪切试验中剪切速率依存性的动态演化过程进行详细研究, 并根据剪切应力和剪切变形状态将其划分为三个阶段。结果表明, 结构面的剪切刚度和能量储存能力的动态演化与裂纹扩展的剪切速率依存性相关, 并随着法向应力和结构面粗糙度系数的增加而增加; 剪切速率依存性与剪切刚度降低阶段具有一致性, 但剪切速率大小对起裂应力没有影响。