泥水盾构泥浆在砂土地层中的渗透特性及对地层强度的影响

对于泥水盾构隧道施工,在有压泥浆渗透到地层的情况下,开挖面表面会形成渗透系数极小的泥膜.通过作用在不透水的泥膜上的泥浆压力来平衡掌子面前方的土水压力,以保证开挖面的稳定.以南京纬三路过江通道工程为背景,选择粒径及级配不同的3种地层,进行室内有压泥浆渗透地层模型试验,探讨有压泥浆在不同地层中的渗透特性及泥浆渗透对地层强度的影响规律.研究发现,对于砂土地层,其渗透系数是影响泥浆渗透深度及泥膜质量的重要因素,渗透系数分别与泥浆渗透深度及滤水量呈线性相关关系,而渗透到地层中的泥浆也会随着地层粒径的变化对砂土地层的剪切强度产生不同且有规律的影响.本文的研究成果可以为泥水盾构合理的泥浆支护压力提供相关参考.

Seepage characteristics of slurry and its influence on ground strength of slurry shield in sand

During slurry shield tunneling,a filter cake with low permeability will be formed on the working face when pressurized slurry infiltrates into the stratum.To ensure the stability of the working face,the slurry pressure which acts on the filter cake that is almost impervious to water to counteract the soil pressure and water pressure.Based on the Nanjing Weisan road river-cross-ing tunnel,three kinds of stratums with different grain size and gradations are picked to carry out a model experiment about pressurized slurry infiltrating into the stratum and to investigate the seepage characteristics and the influence law caused by infiltration of ground strength.According to the results,the permeability coefficient is an important factor influencing the permeability depth and the quality of the filter cake.The permeability depth and the amount of infiltration wa-ter both present a linear relationship with the permeability coefficient.The shear strengths altered by water and slurry show different change laws with the variation of grain size.The research can provide some references for reasonable slurry pressure of slurry shield.