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地层渗透性影响盾尾同步注浆浆液的凝固,从而影响施工期管片上浮。针对目前施工期管片上浮分析缺乏考虑地层渗透性影响的不足,将同步注浆浆液视为牛顿流体、土层简化为多孔介质,利用渗透力学及流体力学原理,提出渗滤效应下同步注浆浆液固结时间的计算方法;进而将不同地层浆液固结时间、浆液性质及施工掘进速度等因素,表征为管片上浮分析的等效梁模型中的浆液未凝固区长度,对等效梁模型进行改进,建立考虑不同渗透性地层中同步注浆浆液固结特性的管片上浮分析模型,并编制有限元程序对其求解。利用此模型对南宁某含粉砂–圆砾、砂层及粉质黏土等地层的盾构区间施工期管片上浮特性进行分析,结果表明:考虑地层渗透性影响的等效梁模型进一步揭示了地层特性影响管片上浮的作用机制,其计算结果与现场实测数据具有更好的一致性,更适合于不同渗透性地层管片上浮分析。同时得到,地层渗透性越小,同步注浆浆液固结时间越长,盾尾浆液压力消散越慢,管片上浮量值越大。
Stratigraphic permeability affects the coagulation of the synchronous tailings grouting slurry, thus affecting the pipe segment floating during construction. In view of the lack of considering the effect of formation permeability on the uplift analysis of pipe during the construction period, the synchronous grouting slurry is regarded as Newtonian fluid, and the soil layer is simplified as porous medium. According to the principles of seepage mechanics and fluid mechanics, the synchronous grouting under percolation effect Then the consolidation time, slurry properties and construction speed of the formation in different formations are characterized by the length of the slurry in the equivalent beam model for the upward analysis of the pipe slice. The equivalent beam model , The model of the rising of the chip considering the consolidation property of synchronous grouting in different permeability strata is established and the finite element program is compiled to solve the problem. The model was used to analyze the uplift characteristics of a section of shield in the silt-boulder, silt, silty clay and other formations in Nanning during the construction period. The results show that the equivalent beam model considering the influence of formation permeability further reveals The effect of formation characteristics on the uplift of the pipe slice has better agreement with the measured data in the field and is more suitable for the uplift analysis of the pipe slice with different permeability. At the same time, the smaller the permeability of the formation, the longer the consolidation grouting time of the grouting slurry, the slower the pressure dissipation of shield slurry at the end, and the greater the float value of the pipe.