Intermediate geotechnical materials such as Victorian Brown Coal (VBC) often exhibit complex fracture characteristics due to the interplay of ductile and brittle behaviour. A diverse set of in situ joint orientations and fracture characteristics are found in the open-cut mines of the Latrobe Valley, Victoria, Australia. As such, the propagation of pre-existing discontinuities plays a significant role in the potential failure mechanisms of open-cut mines in the region. Although field assessment has yielded a range of Victorian Brown Coal in situ joint characteristics, insufficient data exists to determine the relationship between the fracture orientation of VBC and joint compressive strength. To supplement available site investigation data, experimental results of uniaxial compressive tests on pre-fractured Victorian Brown Coal specimens performed under laboratory conditions are presented for various crack angles to determine the relationship between fracture angle and joint compressive strength. Fractured VBC is found to exhibit a reduced uniaxial compressive strength, with appreciably varied fracture propagation characteristics depending on the fracture initiation angle. Laboratory tests were conducted on soaked VBC specimens containing predefined cracks (for angles of 0°, 15°, 30°, 45° and 60° to the axis of symmetry) as well as intact coal specimens, with fracture propagation paths photographed along the specimen surface. Intact coal specimens under compression experienced brittle failure with crack propagation parallel to the direction of loading. For specimens with pre-existing fractures, the crack angle was observed to significantly affect the failure mode and the direction of crack propagation. Obtained results suggest pre-existing crack angles alter the shape of the stress–strain curve, with a range of unconfined compressive strengths and crack initiation strengths presented. It was noted that pre-existing crack angles of 45° yielded the minimum observed failure stress. Given the presence of desiccation cracks, micro-cracks and large-scale jointing within Victorian Brown Coal, compressive strength parameters for a range of joint characteristics are vital to ensuring the ongoing stability of the large open-cut mine slopes within the region.

诸如维多利亚女王时代的褐煤（VBC）之类的中间岩土材料通常由于韧性和脆性行为的相互作用而表现出复杂的断裂特征。在澳大利亚维多利亚州拉特罗布河谷的露天矿中发现了多种多样的原位关节方位和断裂特征。这样，先前存在的不连续性的传播在该地区露天矿的潜在破坏机制中起着重要作用。尽管现场评估得出了维多利亚时代褐煤的一系列原位连接特征，但仍缺乏足够的数据来确定VBC的断裂方向与连接点抗压强度之间的关系。为了补充可用的现场调查数据，给出了在实验室条件下对预裂维多利亚时代褐煤样品进行的单轴压缩试验的实验结果，该试验结果是针对各种裂纹角确定了断裂角与接头抗压强度之间的关系。发现断裂的VBC表现出降低的单轴抗压强度，取决于断裂起始角度，其断裂扩展特性明显变化。在浸泡的VBC试样上进行了实验室测试，该试样含有预定义的裂缝（相对于对称轴的夹角为0°，15°，30°，45°和60°）以及完整的煤试样，沿着试样拍摄了断裂传播路径表面。完整的煤样品在压缩状态下会发生脆性破坏，裂纹扩展与载荷方向平行。对于已经存在断裂的试样，观察到裂纹角度会显着影响破坏模式和裂纹扩展方向。获得的结果表明，预先存在的裂纹角度会改变应力-应变曲线的形状，并呈现出一系列无限制的抗压强度和裂纹萌生强度。注意到预先存在的45°裂纹角产生了最小的观察到的破坏应力。考虑到维多利亚褐煤内部存在干燥裂纹，微裂纹和大规模节理，各种节理特征的抗压强度参数对于确保该地区大型露天矿边坡的持续稳定性至关重要。获得的结果表明，预先存在的裂纹角度会改变应力-应变曲线的形状，并呈现出一系列无限制的抗压强度和裂纹萌生强度。注意到预先存在的45°裂纹角产生了最小的观察到的破坏应力。考虑到维多利亚褐煤内部存在干燥裂纹，微裂纹和大规模节理，各种节理特征的抗压强度参数对于确保该地区大型露天矿边坡的持续稳定性至关重要。获得的结果表明，预先存在的裂纹角度会改变应力-应变曲线的形状，并呈现出一系列无限制的抗压强度和裂纹萌生强度。注意到预先存在的45°裂纹角产生了最小的观察到的破坏应力。考虑到维多利亚褐煤内部存在干燥裂纹，微裂纹和大规模节理，各种节理特征的抗压强度参数对于确保该地区大型露天矿边坡的持续稳定性至关重要。