In the present paper the problems of the nonlinear debonding of anchorage interface, the strain-hardening and rupture of rockbolt, and the progressive damage of heterogeneous rock for the fully grouted rockbolt under axial loads are studied. A micromechanical numerical model is developed and implemented into the finite difference programme, to analyze the load transfer mechanism and damage evolution by introducing the bi-exponential shear slip model of interface, bilinear strain-hardening model of rockbolt and elastic damage model of rock. The close agreement between the simulation results of the proposed model and the theoretical and experimental data validates the model's capability for accurately characterizing the pull-out behavior of the grouted rockbolt. Failure type strongly depends on the strength of rock and anchorage interface, as well as the anchorage length. In particular, when rock strength is low, strain energy is predominantly dissipated through rock damage, leading to the interface failing to fully mobilize its load transfer effect, especially at a relatively long anchorage length. Moreover, the excessive interfacial adhesion performance causes a large range of serious damage in rock near the interface and leads to peak pull-out load even lower than the rockbolt with poor interfacial bonding properties. Finally, the critical anchorage length is investigated and the load transfer mechanism of the fully grouted rockbolt is clarified by comparing the case with or without rock damage. It is therefore very useful of the developed micromechanical model, since it provides an essential understanding of the load transferring capacity and failure type of the fully grouted rockbolt, especially under rock damage.

中文翻译：

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用于模拟轴向载荷下全灌浆锚杆的载荷传递行为和损伤演变的微观力学模型


本文研究了锚杆锚杆界面的非线性脱粘、锚杆的应变硬化和破裂以及轴向载荷作用下非均质岩的渐进损伤等问题。通过引入界面双指数剪切滑移模型、锚杆双线性应变硬化模型和岩石弹性损伤模型，开发微力学数值模型并将其应用于有限差分程序中，分析了载荷传递机理和损伤演变。所提模型的仿真结果与理论和实验数据之间的紧密吻合验证了该模型准确表征灌浆锚杆拉拔行为的能力。破坏类型在很大程度上取决于岩石和锚固界面的强度以及锚固长度。特别是，当岩石强度较低时，应变能主要通过岩石损伤消散，导致界面无法完全调动其载荷传递效应，尤其是在相对较长的锚固长度下。此外，过高的界面粘附性能会在界面附近的岩石中造成大范围的严重损伤，并导致峰值拉出载荷甚至低于界面结合性能较差的锚杆。最后，研究了临界锚固长度，并通过比较有或没有岩石损伤的情况，阐明了全灌浆锚杆的载荷传递机制。因此，它对开发的微力学模型非常有用，因为它提供了对全灌浆锚杆的载荷传递能力和失效类型的基本理解，尤其是在岩石损伤下。