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不同剪切速率下充填节理的剪切特性对动态荷载作用下工程岩体的安全稳定性有着重要的影响。为了研究剪切速率对充填节理的剪切力学特性的影响,通过花岗岩试块中间充填天然河砂模拟充填节理。采用RMT-150C电伺服试验机进行直接剪切试验,研究了法向压力、剪切速率和充填厚度对充填节理的剪切力学特性的影响。试验结果发现,充填节理的剪切应力-位移曲线属于屈服剪切型,分为弹性阶段、过渡阶段和滑移阶段,无明显峰值强度,在滑移阶段剪切应力继续增加,增加速率与法向压力大小有关。随着剪切速率的增加,充填节理的剪切强度和内摩擦角略有增加。为了考虑充填节理剪切应力-位移关系的非线性变化过程,采用双曲线形式对弹性阶段的应力-位移曲线进行拟合,结果较好,并提出初始剪切刚度和刚度影响系数描述其变形特性。剪切速率和法向压力的增加会大幅度增加初始刚度,充填厚度对两个参数的影响与法向压力有关。对于无起伏度的平直节理,剪切速率和充填厚度对剪切强度影响较小,但对充填节理的变形特性有重要的影响。
The shear characteristics of filling joints under different shear rates have an important influence on the safety and stability of engineering rock mass under dynamic loading. In order to study the influence of shear rate on the shear mechanics characteristics of filling joints, natural filling sand was used to simulate the filling joint through the middle of granite test blocks. The direct shear test was carried out by using the RMT-150C electric servo tester to study the effect of normal pressure, shear rate and filling thickness on the shear mechanics characteristics of filling joints. The experimental results show that the shear stress-displacement curve of filling joints belongs to the yield shear type and is divided into elastic stage, transitional stage and slip stage, with no obvious peak strength. The shear stress continues to increase during the slip stage, To the size of the pressure. With the increase of shear rate, the shear strength and internal friction angle of filling joint increase slightly. In order to consider the nonlinear change process of the shear stress-displacement relationship of filling joints, the hyperbolic model is used to fit the stress-displacement curve of the elastic phase. The results are good and the initial shear stiffness and stiffness influence coefficient are described to describe the deformation characteristics . The increase of shear rate and normal pressure will greatly increase the initial stiffness. The effect of filling thickness on the two parameters is related to the normal pressure. For straight joints without undulation, the shear rate and filling thickness have little influence on the shear strength, but have an important influence on the deformation characteristics of the filling joint.