基于HOEK-BROWN软化模型的支护结构稳定性分析

Stability analysis of support structure based on HOEK-BROWN strain-softening model

根据HOEK-BROWN强度准则,引入计算岩体峰后地质强度指标及其强度参数的方法,并总结岩体临界软化参数η*的计算方法,分析不同因素对η*的影响。基于锚喷组合支护特征曲线,利用收敛-约束原理分析开挖方法和支护时机对隧道支护结构稳定性的影响。研究结果表明:采用不同开挖方法获得的围岩特征曲线和纵向变形曲线存在差异;与弹塑性模型相比,采用应变软化模型计算得到的支护结构稳定性系数更高;采用台阶法开挖能大大提高隧道支护结构稳定性系数;距离开挖面越远处设置支护可以使其稳定性系数更高,但不利于围岩变形的控制,在实际支护设计中,应综合考虑支护结构稳定性和围岩变形控制这2个因素。

Based on HOEK-BROWN strength criterion,the method of calculating the post-peak geological strength index of rock mass and its strength parameters was introduced,and the calculation method of the critical softening parametersη*of rock mass was summarized.The influence of different factors on the critical softening parametersη*of rock mass was analyzed.Based on the anchor-spray combined support characteristic curve,the convergence-confinement principle was used to analyze the influence of excavation method and support timing on the stability of tunnel support structure.The results show that the ground reaction curves and longitudinal deformation profiles obtained by different excavation methods are different.Compared with the elastic-plastic model,the stability coefficient of the supporting structure calculated by the strain softening model is higher.Excavation scheme of bench method can greatly improve the stability coefficient of the tunnel support structure.The larger distance from the excavation surface can lead to a higher stability coefficient of support structure,but it is not conducive to the control of surrounding rock deformation.In actual situations,the two factors of the stability of the support structure and the deformation control of the surrounding rock should be considered comprehensively.