豆砾石回填降低双护盾TBM卡机风险的效用影响分析

双护盾TBM掘进豆砾石回填速度对于围岩支护效果具有一定影响,以西藏某公路隧道护盾卡机段为研究对象,构建了双护盾TBM掘进过程数值模拟分析模型,以回填物强度变化直接反应回填时间同时考虑回填段长度变化,研究豆砾石回填对围岩屈服、收敛变形、护盾接触面积、设备推进所需克服摩阻力等影响规律,进而研究豆砾石回填工序对于降低双护盾TBM卡机风险的减灾作用。结果表明：豆砾石快速回填不会改变围岩收敛变形宏观分布特征,对围岩塑形屈服区的总体分布、屈服类型及体积具有一定影响；豆砾石快速回填可以控制围岩收敛变形,减小围岩与护盾接触面积,进而降低TBM推进所需克服护盾摩阻力,具有一定的降低卡机风险效果,但对于挤压变形较大洞段,需要与其他主动防控措施相结合采用,研究结果可为相类似工程进行双护盾TBM护盾卡机风险防控措施选择提供参考。

Impact analysis of pea gravel backfill on reducing the risk of double shield TBM machine entrapment

The speed of pea gravel backfill has some impact on the support effect of the surrounding rock in the double-shield TBM tunneling. Taking the shielding type machine entrapment section of a highway tunnel in Tibet as the research object, we constructed the numerical simulation analysis model for the double shield TBM excavation process, directly reflecting the backfill time with the change in backfill strength, considering the change of the length of the backfill section, studying the influence law of the pea gravel backfill on the yield of surrounding rock, convergence deformation, contact area of the shield, and the friction resistance required for the equipment advancement. Further we made a study on the disaster reduction function of pea gravel backfill process on reducing the risk of double shield TBM machine entrapment. The results show that the pea gravel rapid backfill does not change the macroscopic distribution characteristics of convergence deformation of the surrounding rock, and has some influence on the general distribution of surrounding rock plastic yielding zone, yield type and volume of the surrounding rock plastic yielding zone. The pea gravel rapid backfill can control convergence deformation of the surrounding rock and decrease the contact area between surrounding rock and shield, and reduce the friction resistance of shield that TBM propulsion needs to overcome, thus reducing the risk of machine entrapment. But for the large squeezing deformation section of the tunnel, it needs to be combined with other active prevention and control measures to use. The research results can provide a reference for similar projects on the selection of risk prevention and control measures of double shield TBM shielding type machine entrapment.