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冲击载荷下节理岩体锚固系统剪切动响应分析

Shear dynamic response of jointed rock mass anchorage system under impact load

  • 摘要: 锚固节理岩体动力破坏极易在地下工程开发和能源工程中引发灾害。考虑边界效应、岩块-粘结层-锚杆的耦合作用及损伤劣化行为,采用有限元显式动力学方法,改进落锤冲击试验建立了加锚节理岩体侧向冲击三维计算模型,分析了锚杆破断面切应变积聚和动力颈缩破断特征,揭示了加锚节理岩体冲击破坏演化过程及系统的能量演化规律,阐明了粘结层冲击刚度劣化累积损伤机制以及不同边界效应下岩块的冲击速度演化特性。研究结果表明:冲击作用下加锚节理岩体变形破坏响应过程与静载作用下有明显不同,CNL和CNS不同边界效应下锚杆的动力破坏、粘结层的累积损伤以及系统的能量演化规律相似,但由于CNS边界条件提供了额外的法向应力增量,岩体承受更大的法向应力约束,受冲击影响相对较小。所得结论对于揭示岩体锚固动力失效具有一定意义。

     

    Abstract: The dynamic damage of anchored joint rock masses is very likely to cause disasters in underground engineering development and energy engineering. Considering the boundary effect,the coupling effect of rock massbinder layer-anchor rod and damage deterioration behavior,a three-dimensional calculation model of lateral impact of rock mass with anchored joints was established by using the finite element explicit dynamics method and improving the droping weight test. The shear strain accumulation and dynamic necking breakage characteristics of rock bolt breaking surface were analyzed. The impact damage evolution process and the energy evolution law of the system were revealed. The cumulative damage mechanism of impact stiffness deterioration in the bonded layer and the impact velocity evolution characteristics of the rock mass under different boundary effects were elucidated. The results show that the deformation and damage response of the rock mass with anchored joints under impact is significantly different from that under static load,and the dynamic damage of rock bolts,the accumulated damage of bond layer and the energy evolution of the system under different boundary effects of CNL and CNS are similar,but the rock mass is subjected to greater normal stress constraint and is relatively less affected by the impact because of the additional normal stress increment provided by CNS boundary conditions. The conclusions obtained have implications for revealing the dynamic failure of rock anchorage.

     

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