开挖作用下滑剪破坏下盘边坡扰动范围计算及稳定性评价方法

Disturbed zone calculation and stability evaluation method of footwall slope with slip-shear failure under excavation

滑剪破坏型下盘边坡是矿山工程中经常出现的一种顺层边坡,具有突发性强、破坏范围广的特点。如何快速、准确地确定开挖塑性扰动区并评估其稳定性对边坡安全控制至关重要。本文首先通过数值模拟揭示了该类边坡的破坏模式和特征。然后,根据其破坏模式,建立了描述开挖扰动区的数学方程。最后,提出了一种计算下盘边坡开挖扰动区和稳定性的力学截断新方法(MTM)。主要结果有,MTM方法考虑岩体单轴抗压强度,计算过程无需一般极限平衡方法需要的多次循环迭代,计算过程简便。MTM方法可以准确地表征扰动区,计算得到的极限边坡高度、扰动厚度和安全系数与数值模拟结果较吻合,且评价结果比数值模拟更安全。扰动区的最大厚度决定了锚索锚固端的深度,分区是为了指明加固的重点范围。该方法为下盘边坡的工程施工和监测提供指导。

The slip-shear failure type of footwall slope is a type of beding slope that often appears in mining engineering,which has the characteristics of strong suddenness and extensive failure range.How to quickly and accurately define the plastic disturbed zone of excavation and evaluate its stability is vital for safety control.In this work,the failure mode and characteristics of this type of slope are first revealed by numerical simulation tests.Then,according to the failure mode of the slope,considering the uniaxial compressive strength of the rock mass,the mathematical equation describing the excavation disturbed zone is established.Finally,a new mechanical truncation method(MTM)is proposed to calculate the excavation disturbed zone and stability of the footwall slope.It is found that the MTM can accurately characterize the disturbed zone.The calculated limit cutting depth,disturbance thickness,and safety factor are in good agreement with the numerical simulation results,and the evaluation results are safer than numerical simulations.The maximum thickness of the disturbed zone determines the depth of the anchor end of the anchor cable.The disturbed zone indicates the critical area for reinforcement and provides engineering construction and monitoring guidance for the footwall slope.