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DEM investigation of rock/bolt mechanical behaviour in pull-out tests
Particuology ( IF 4.1 ) Pub Date : 2020-02-03 , DOI: 10.1016/j.partic.2019.12.006
Na Che , Huaning Wang , Mingjing Jiang

Rock bolt anchorage performance is crucial for tunnel support safety. We investigate the mechanical behaviour of reinforced rock and the bolts that reinforce it from the micro-scale to the macro-scale. Bolt pull-out tests were performed on soft rock using the distinct element method, in which a new contact model that considers bond size, is employed to constrain the main rock mechanical behaviour. The minimum sample width and height values for which the boundary effect can be neglected are first proposed through numerous tests on the influence of sample size on peak load and bond breakage. The influence of sample width is substantially greater than that of sample height. We then select an appropriate sample size to study the influence of bolt embedment length and confining pressure on the mechanical behaviours of the rock and bolt. The results show that increased rock bolt embedment length and confining pressure can increase the peak load; however, the bolt length effect is limited when exceeding the critical anchorage length. In cases without confining pressure, bond breakage occurs in the rock around the grout-rock interface and the breakage zone is rectangular, whereas in cases under confining pressure, the breakage zone presents an inverted cone shape. We use our results to discuss the influence of bond strength at the bolt–grout interface on the peak load and failure mode. The failure mode changes gradually from complex failure to single failure along the bolt–grout interface with decreasing interfacial bond strength.



中文翻译:

拔出测试中岩石/螺栓力学行为的DEM研究

锚杆锚固性能对于隧道支护安全至关重要。我们研究了加筋岩石的机械性能以及从微观到宏观的加强筋的螺栓。螺栓拔出试验是使用独特元素方法在软岩上进行的,其中采用了考虑粘结尺寸的新接触模型来约束主要岩石的力学行为。首先通过对样本大小对峰值载荷和键断裂的影响的大量测试,提出了可以忽略边界效应的最小样本宽度和高度值。样品宽度的影响远大于样品高度的影响。然后,我们选择合适的样本量来研究锚杆埋入长度和围压对岩石和锚杆力学性能的影响。结果表明,增加锚杆埋入长度和围压可以增加峰值荷载。但是,当超过临界锚固长度时,螺栓长度的影响会受到限制。在没有约束压力的情况下,在水泥浆-岩石界面周围的岩石中会发生粘结断裂,断裂区域是矩形,而在约束压力的情况下,断裂区域呈倒锥形。我们使用我们的结果来讨论螺栓-灌浆界面处的粘结强度对峰值载荷和破坏模式的影响。随着界面粘结强度的降低,破坏模式沿螺栓-灌浆界面逐渐从复杂破坏变为单一破坏。当超过临界锚固长度时,螺栓长度的影响会受到限制。在没有约束压力的情况下,在水泥浆-岩石界面周围的岩石中会发生粘结断裂,断裂区域是矩形,而在约束压力的情况下,断裂区域呈倒锥形。我们使用我们的结果来讨论螺栓-灌浆界面处的粘结强度对峰值载荷和破坏模式的影响。随着界面粘结强度的降低,破坏模式沿螺栓-灌浆界面逐渐从复杂破坏变为单一破坏。当超过临界锚固长度时,螺栓长度的影响会受到限制。在没有约束压力的情况下,在水泥浆-岩石界面周围的岩石中会发生粘结断裂,断裂区域是矩形,而在约束压力的情况下,断裂区域呈倒锥形。我们使用我们的结果来讨论螺栓-灌浆界面处的粘结强度对峰值载荷和破坏模式的影响。随着界面粘结强度的降低,破坏模式沿螺栓-灌浆界面逐渐从复杂破坏变为单一破坏。我们使用我们的结果来讨论螺栓-灌浆界面处的粘结强度对峰值载荷和破坏模式的影响。随着界面粘结强度的降低,破坏模式沿螺栓-灌浆界面逐渐从复杂破坏变为单一破坏。我们使用我们的结果来讨论螺栓-灌浆界面处的粘结强度对峰值载荷和破坏模式的影响。随着界面粘结强度的降低,破坏模式沿着螺栓-灌浆界面逐渐从复杂破坏变为单一破坏。

更新日期:2020-02-03
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