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盾构施工过程中地质条件变化、刀盘旋转切割土体、停盾拼装管片等因素会造成开挖面推力的波动,从而在开挖面前方产生超孔压,此超孔压对开挖面稳定性的影响需进行分析。首先通过建立分层土分析模型,结合太沙基固结理论,得到开挖面前方超孔压的计算方法;进而采用楔形体模型,给出超孔压对开挖面稳定性影响的计算方法。计算结果显示超孔压将显著降低开挖面的安全系数,因此在开挖面最小支护力的计算中需考虑推力波动变化的影响。最后通过参数分析给出了不同工况下产生的超孔压及其对开挖面安全系数影响的大小,为盾构施工参数的制定提供了参考。
In the process of shield construction, the geological conditions change, the cutter disc rotates and cut the soil body, and the shield shield assembled pipe slice and other factors will cause the fluctuation of excavation surface thrust, so as to generate excess pore pressure in front of the excavation face. The influence of surface stability needs to be analyzed. First, through the establishment of the layered soil analysis model, combined with the theory of the consolidation of the Tai Shaji, the calculation method of the excess pore pressure in front of the excavation surface is obtained. Then the calculation method of the influence of the excess pore pressure on the stability of the excavation surface is given by using the wedge model . The calculation results show that the excess pore pressure will significantly reduce the safety factor of the excavation face. Therefore, the influence of thrust fluctuation must be considered in the calculation of the minimum support force of the excavation face. Finally, the parameters of overhole pressure generated under different working conditions and its influence on the safety factor of excavation surface are given through the analysis of parameters, which provides a reference for the formulation of shield construction parameters.