隧道开挖面预注浆加固稳定性理论计算模型

Theoretical Calculation Model for Stability of Tunnel Excavation Face with Pre-grouting Reinforcement

为了支撑隧道开挖面预注浆参数的定量化设计,建立考虑预注浆加固作用的开挖面稳定性计算模型,采用极限平衡法及强度折减法推导开挖面稳定系数计算公式。研究表明:理论模型计算结果与数值模型、模型试验结果吻合较好,平均相对误差为4.3%;隧道开挖面稳定性随着围岩力学参数、黏聚力增强系数、预注浆范围的增加而提高;开挖面临界注浆范围约为0.4D~0.8D,当预注浆范围超过临界注浆范围后,预注浆加固效果最佳,且开挖面稳定性不再受加固范围影响;得到考虑隧道围岩强度参数、开挖方法、未支护段长度、黏聚力增强系数的开挖面安全系数,为预注浆参数设计提供参考。

To support the quantitative design of pre-grouting parameters for tunnel excavation faces,a stability calculation model for excavation faces considering the effect of pre-grouting reinforcement was established.The ultimate equilibrium method and the strength reduction method were employed to derive a calculation formula for the stability coefficient of the excavation face.The study indicates that the theoretical model's results closely align with numerical models and experimental results,with an average relative error of 4.3%.The stability of the tunnel excavation face is improved with increase in the mechanical parameters of the surrounding rock,cohesion enhancement factor,and the pre-grouting range.The critical grouting range for the excavation face is approximately 0.4D~0.8D;when the pre-grouting range exceeds this critical value,the reinforcement effect is optimal,and the stability of the excavation face is no longer affected by the reinforcement range.A safety coefficient for the excavation face is proposed,considering parameters such as surrounding rock strength,excavation method,unsupported section length,and cohesion enhancement factor,providing a reference for the design of pre-grouting parameters.