通过复合岩石四点弯曲试验,利用CCD相机作为观测工具,采用数字散斑相关方法,对一组以不同强度细砂岩组成的复合岩石试件进行试验研究,分析层间滑移对复合岩石破坏的影响规律。结果表明:(1)复合岩石破坏过程中会出现多个荷载峰值及突降,这些荷载峰值及突降与裂缝的产生有关,当岩石试件某一层产生裂缝,同步释放储存能,从而导致荷载曲线突降;(2)岩石裂缝在竖直方向出现位置为受压弯曲和层间滑移共同作用的结果,四点弯试验中两点加载提供竖向压力,层间滑移提供水平摩擦力,导致最大水平应变位置偏移,在岩石底部向上10 mm左右;(3)复合岩石裂缝在水平方向出现位置由层间滑移控制为主、受压弯曲控制为辅;(4)对复合岩石层间滑移进行分析时发现,层间滑移发生位置与裂缝出现位置高度重合且为先发生滑移后产生裂缝。研究成果对研究复合岩石的破坏规律具有参考价值。

Through the four-point bending experiment, using CCD camera as the observation means and the digital scattering correlation method, a group of composite rock specimens composed of fine sandstones with different strengths are experimentally investigated to analyze the influence law of interlayer slip on the damage of composite rocks. The results show that: (1) Multiple load peaks and sudden drops occur during the damage of composite rock, which are related to the generation of cracks, and when cracks are generated in one layer of the rock specimen, the stored energy is released synchronously, which leads to a sudden drop in the load curve. (2) Rock cracks appear in the vertical direction as a result of the joint action of pressure bending and interlayer slip, two-point loading in the four-point bending experiment provides vertical pressure, and interlayer slip provides horizontal friction, resulting in a shift in the location of the maximum horizontal strain, which is about 10 mm upward at the bottom of the rock. (3) The location of the composite rock cracks appearing in the horizontal direction is controlled mainly by interlayer slip and supplemented by pressurized bending. When analyzing the interlayer slip of the composite rock, it is found that the location of interlayer slip and the cracks are highly coincident, and the slip occurs first and then the cracks are generated. The above research results are important reference value for the study of the damage law of composite rocks.