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首页> 外文期刊>Advances in civil engineering >An Experimental Study of the Uniaxial Failure Behaviour of Rock-Coal Composite Samples with Pre-existing Cracks in the Coal
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An Experimental Study of the Uniaxial Failure Behaviour of Rock-Coal Composite Samples with Pre-existing Cracks in the Coal

机译：煤炭复合样品与煤中预先裂缝的单轴失效行为的实验研究

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Many hazards encountered during coal mining can be caused by the instability and failure of the composite structure of the coal seam and the surrounding rock strata. The defects present in the coal affect the structural stability of the composite structure. In this study, uniaxial compression tests were conducted on sandstone-coal composite samples with pre-existing cracks in the coal, combined with tests performed with an acoustic emission (AE) device and a digital video camera. The strength, macrofailure initiation (MFI), and failure characteristics of composite samples, as influenced by the coal’s pre-existing cracks, were analysed. The coal’s pre-existing cracks were shown to reduce the strength, promote the occurrence of MFI, and affect the failure characteristics of the samples. Vertical penetration cracks had much more pronounced effects on strength and MFI occurrence, especially vertical penetration cracks that penetrated through the centre of the coal. Horizontal penetration cracks had a much reduced effect on strength and MFI occurrence. The MFI caused a step shape in the stress-strain curve accompanied with a peak energy index signal and occurred around the original coal cracks. The MFI models predominantly exhibited crack initiation from the pre-existing coal cracks and surface spalling caused by crack propagation. The intact composite sample failure presented as an instantaneous failure, whereas the composite samples containing the pre-existing cracks showed a progressive failure. The failures of composite samples occurred predominantly within the coal and displayed an X-typed shear failure accompanied by a small splitting failure. Both the coal and sandstone were destroyed in the composite sample with vertical penetration cracks through the centre of the coal. Failure of the coal occurred through a splitting failure accompanied by a small X-typed shear failure, while the sandstone showed a splitting failure induced by crack propagation in the coal.
机译：在煤矿期间遇到的许多危险可能是由煤层和周围岩石地层的复合结构的不稳定性和失效引起的。煤中存在的缺陷会影响复合结构的结构稳定性。在该研究中，在砂岩 - 煤复合样品上进行单轴压缩试验，其中煤中预先存在，与用声发射（AE）设备和数字摄像机进行的测试结合。分析了由煤预先存在裂缝的影响的复合样品的强度，宏观发酵脂肪（MFI）和失效特性。煤的预先存在的裂缝被证明可以降低强度，促进MFI的发生，影响样品的失效特征。垂直渗透裂缝对强度和MFI发生的影响更加明显，特别是穿过煤中心穿透的垂直穿透裂缝。水平渗透裂缝对强度和MFI的效果大大。 MFI在应力 - 应变曲线中引起步进形状，伴随着峰值能量指数信号并发生在原始煤裂缝周围。 MFI型号主要从预先存在的煤裂纹和由裂纹传播引起的表面剥落表现出裂纹启动。完整的复合样品失败呈现为瞬时失效，而含有预先存在的裂缝的复合样品显示出渐进式失败。复合样品的故障主要发生在煤中，并显示出伴随着小分裂失败的X型剪切衰竭。煤和砂岩在复合样品中被破坏，通过煤中心垂直穿透裂缝。煤的失效通过分裂失败伴随着小的X型剪切失效，而砂岩显示通过煤中的裂纹繁殖引起的分裂失败。

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