The method of backfill in underground mining is important for ground control as well as material recycling and energy efficiency. Even though extensive testing and field studies of backfill have been conducted, less is known about the detailed damage and fracturing that occurs directly at the rock/backfill interface. In this paper, cylindrical specimens containing an inner diameter of backfill and an outer diameter of rock (RB) were tested under triaxial compression. Acoustic emissions (AE) were used throughout testing, and X-ray computed tomography (CT) scanning was conducted before loading was applied and after the specimens had failed. The high-resolution CT images were then converted into point clouds to isolate the fractures and visualize them in three dimensions. The point clouds clearly show that fracturing occurred both in the rock and along with the contact between rock and backfill, while very little fracturing was found to occur in the backfill. Based on the point cloud and AE results, a unique evolution of fracturing is found to occur that includes two stages of shear fracturing in the rock, tensile fracturing along with the rock/backfill interface, and final tensile fracturing in the rock after delamination from the backfill, all of which contributed to the nonlinear stress–strain response. This paper presents a novel approach for investigating the initiation and propagation of 3D fractures in laboratory testing and can offer a useful reference for further studies on the mechanics of bi-material structures.

地下采矿中的回填方法对于地面控制以及材料回收和能源效率很重要。尽管已经对回填土进行了广泛的测试和现场研究，但对直接发生在岩石/回填土界面的详细损坏和破裂知之甚少。在本文中，包含回填内径和岩石外径 (RB) 的圆柱形试样在三轴压缩下进行了测试。在整个测试过程中使用声发射 (AE)，并在施加载荷之前和试样失效后进行 X 射线计算机断层扫描 (CT) 扫描。然后将高分辨率 CT 图像转换为点云以隔离裂缝并在三个维度上对其进行可视化。点云清楚地表明，在岩石中以及岩石与回填土之间的接触处都发生了压裂，而在回填物中几乎没有发现发生压裂。根据点云和声发射结果，发现发生了独特的压裂演化，包括岩石中的剪切压裂两个阶段，沿岩石/回填界面的拉伸断裂，以及从岩石分层后岩石中的最终拉伸断裂。回填，所有这些都有助于非线性应力应变响应。本文提出了一种在实验室测试中研究 3D 裂缝起裂和扩展的新方法，可为进一步研究双材料结构的力学提供有用的参考。而在回填物中几乎没有发现破裂。根据点云和声发射结果，发现发生了独特的压裂演化，包括岩石中的剪切压裂两个阶段，沿岩石/回填界面的拉伸断裂，以及从岩石分层后岩石中的最终拉伸断裂。回填，所有这些都有助于非线性应力应变响应。本文提出了一种在实验室测试中研究 3D 裂缝起裂和扩展的新方法，可为进一步研究双材料结构的力学提供有用的参考。而在回填物中几乎没有发现破裂。根据点云和声发射结果，发现发生了独特的压裂演化，包括岩石中的剪切压裂两个阶段，沿岩石/回填界面的拉伸断裂，以及从岩石分层后岩石中的最终拉伸断裂。回填，所有这些都有助于非线性应力应变响应。本文提出了一种在实验室测试中研究 3D 裂缝起裂和扩展的新方法，可为进一步研究双材料结构的力学提供有用的参考。伴随岩石/回填土界面的拉伸断裂，以及从回填土分层后岩石中的最终拉伸断裂，所有这些都导致了非线性应力应变响应。本文提出了一种在实验室测试中研究 3D 裂缝起裂和扩展的新方法，可为进一步研究双材料结构的力学提供有用的参考。伴随岩石/回填土界面的拉伸断裂，以及从回填土分层后岩石中的最终拉伸断裂，所有这些都导致了非线性应力应变响应。本文提出了一种在实验室测试中研究 3D 裂缝起裂和扩展的新方法，可为进一步研究双材料结构的力学提供有用的参考。