双根恒阻大变形锚杆在冲击载荷作用下的理论模型
Theoretical model of the double constant-resistance-large-deformation bolts under impact load
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摘要: 为了指导工程开采中动力灾害下恒阻大变形锚杆群对围岩体的稳定性支护, 基于双根恒阻大变形锚杆的并联支护原理和霍普金森冲击作用下双根恒阻锚杆的拉伸实验研究, 建立了并联作用的双根恒阻大变形锚杆在冲击载荷下的力学模型, 并且通过实验结果对比验证了理论模型的可靠性和正确性, 进一步得到了双根恒阻大变形锚杆的位移时程曲线和载荷位移关系曲线。研究表明:并联作用的双根恒阻大变形锚杆在冲击载荷作用下, 首先通过杆柄的拉伸产生弹性变形;当杆柄内力达到锚杆恒阻力后, 开始产生结构变形, 套管和杆柄发生相对滑移;套管速度减为零时, 结构变形结束, 套管和杆柄共同弹性恢复。此外, 冲击载荷作用下双恒阻锚杆的位移峰值要明显滞后于载荷峰值。Abstract: In order to guide the support of the surrounding rock mass with constant-resistance-large-deformation (CRLD) bolts under the dynamic disaster during the engineering mining, a theoretical model is established for the double CRLD bolts acting in parallel under the impact load.The model is based on the principle of parallel support of the double CRLD bolts and the Hopkinson impact tensile test of the double CRLD bolts.Moreover, the reliability and correctness of the theoretical model are verified by the comparison to the test results.The displacement-time relation and the load-displacement relation of the double CRLD bolts are further obtained.The research shows that the double CRLD bolts acting in parallel undergoes three stages under the impact load:initially elastic deformation, structural deformation and late elastic recovery.Firstly, the elastic deformation occurs through the stretching of the shank bar.When the internal force of the shank reaches the constant resistance of the CRLD bolts, the structural deformation begins to occur by the relative slippage of the sleeve pipe and the shank rod.Once the velocity of the sleeve is reduced to zero, the structural deformation is completed and the sleeve and the shank rebound together.In addition, the displacement peak of the double CRLD bolts obviously lags behind the load peak under the impact load.