均质围岩灌浆锚杆应力的近似解析解

灌浆锚杆与岩体介质的耦合机理和支护效果的解析评估,目前尚处于研究进展阶段。本文对全长处于均质围岩塑性屈服区的弹性锚杆,按围岩弹-脆-塑性应力应变关系和Mohr-Coulomb屈服准则,给出了锚杆的应力、位移和介质交界面屈服长度的解析表达式。这一解析模型考虑了锚杆切应力 对围岩的剪切抑制作用。把它应用于Kielder试验洞,计算和实测结果吻合尚好。对Kielder洞探讨了加大杆长的效益,计算表明,加大杆长的效益并不显著,该洞采用1.8 m的杆长是合适的。所提出的解析模型可用于非轴对称地下洞室,是一个较简明的解答,有利于工程初步设计阶段的参数识别,支护荷载及其效果的评估。

Approximate analytical solution of grouted bolt stress in homogeneous rock mass

Grout bolting is widely used as an economical reinforcement of surrounding rocks in underground engineering. However, the mechanism of bolt and rock interaction is not yet fully understood, and analytical evaluation of the reinforcement effect is still underway. This paper derives analytical expressions for the stress, displacement and yield depth at the medium interface for elastic bolts fully embedded into a plastic zone of homogeneous surrounding rock, using the elastic-brittle-plastic model and Mohr-Coulomb yield criterion. This analytical model takes into account the inhibition effects of bolt shear stress ?b on rock. The simulation results of the Kielder test tunnel are in good agreement with measurements. Comparison analyses using different bolt lengths for this tunnel indicate that an anchor length of 1.8 m is appropriate and the benefit of longer bolts is insignificant. Our analytical model is applicable to non-axisymmetric underground caverns and its solutions are simple and clear, helping identify parameters and evaluate support load and support effect in preliminary design phase.