基于双指数剪切滑移模型的全长锚固锚杆荷载传递机制分析

Analysis of load transfer mechanism for fully grouted rockbolts based on the bi-exponential shear-slip model

为了准确分析全长锚固锚杆荷载传递机制,提出以锚固界面的双指数曲线剪切滑移模型和锚杆线性强化弹塑性本构模型为基础的数值模型,并通过拉拔试验验证此模型,然后基于此模型分析不同锚固长度的锚杆中载荷传递规律,探讨锚固长度为1.5m的锚杆中轴向应力和剪应力分布情况。结果表明此数值模型能够很好的描述锚杆在拉拔荷载作用下发生界面滑脱失效和拉伸破坏2种破坏形式,以及能够准确判断在整个拉拔历程中锚杆是否发生屈服,试验结果验证了该模型的合理性。

A numerical model was presented in this study to analyze the load-transfer mechanism of fully grouted rockbolts,which was based on the bi-exponential shear-slip model of the anchorage interface and the linear enhanced elasto-plastic constitutive model of the rockbolt. It was validated by pull-out tests. The load-transfer characteristics with different anchorage lengths were studied in detail. The distribution of axial stress and shear stress along the rockbolt with anchorage length of 1.5 m was examined. The numerical results showed that it could not only describe the failure modes of interface slippage and tensile failure of rockbolts,but also determine whether the rockbolt yields during the full-range process of pullout. The reliability and accuracy of the proposed analytical model were verified by experimental pullout tests.