盾构带压进舱开挖面稳定性分析及合理进舱换刀区间判断研究

Stability Analysis of Excavation Surface Induced by Shield Chamber Opening under Pressure and Rational Position of Cutter Replace

为探究盾构隧道施工中带压进舱换刀作业的合理区段,分析带压进舱过程中开挖面的失稳规律,依托佛莞城际铁路狮子洋隧道工程,对隧道穿越不同地层进行开挖面稳定性计算分析,得到不同地层环境下的最高带压进舱埋深;提出选取适合盾构带压换刀作业断面的判别方法,并针对依托工程给出合理换刀位置选择的建议。研究得出:1)针对狮子洋隧道工程圆砾土、强风化泥质砂岩及中风化泥质砂岩3种地层,围岩自身稳定性越强,进舱时所能承受的上覆土越高,开挖面变形越小,越适合进舱作业;2)对于淤泥地层而言,由于自身流动性较强、稳定性差,不适合带压进舱作业;3)对比实际施工进舱换刀作业时施加的支护力,楔形滑块模型计算方法所得最小支护压力偏大,数值计算方法所得结果偏小,但更接近实际极限情况;4)结合现场带压进舱作业验证,本文提出的方法可以较为准确地判断隧道全区段带压进舱的可行性,可初步给出适合带压进舱工作的盾构隧道施工区间,为实际工程选择进舱作业位置给出建议。

The instability rules of excavation face during cutter replacement are investigated using the Shiziyang tunnel of the Foshan-Dongguan intercity railway as an example to study the rational section for cutter replacement under pressure during shield tunneling.The stability of the excavation surface is calculated and analyzed under various strata,obtaining the maximum depth of the tunnel when entering the chamber under pressure.Furthermore,the indentifying methods for cutter replacement sections are put forward,and corresponding proposals are given.The following results are revealed:(1)The stronger the stabilities of the gravel soil,and strongly-and moderately-weathered argillaceous sandstones are revealed in the Shiziyang tunnel,the higher the overburden soil for the chamber entering.The smaller the deformation of the excavation face,the more beneficial the chamber entering might be.(2)Due to the silt formation′s high liquidity and poor stability,chamber opening under pressure should not be applied.(3)Comparative results of supporting force applied during chamber opening and cutter replacement indicate that the minimal supporting force obtained using the wedge-sliding block model calculation method is relatively large.In contrast,the numerical calculation method results are relatively small but agree more with the actual limit.(4)Field application results show that the indentifying methods for chamber entering section under pressure are feasible,which can preliminarily provide rational sections.