泥水盾构泥膜渗透性及其对开挖面稳定性影响

发布时间：2018-05-14 05:32

本文选题：泥水盾构 + 泥浆渗透　；参考：《岩土工程学报》2017年11期

【摘要】：泥膜是维持泥水盾构开挖面稳定的关键因素。通过渗透柱试验研究了加压泥浆向砂土渗透、并在砂土表面形成泥膜的行为,获得了泥膜渗透性与时间的关系。结果显示泥水盾构在开挖时,由于刀盘不断切削泥膜,开挖面上只能形成微透水的泥膜;当拼装管片时,刀盘停止转动,开挖面上则会形成难透水的泥膜。建立了在开挖面上设置微透水的泥膜的二维数值模型,通过瞬态渗流分析获得土体孔压的最大值。根据地层孔压计算了失稳区域内的渗透力,获得了不同泥浆压力下在泥膜表面和地层中的分配比例。当有效泥浆压力越大,孔压在泥膜和失稳区以外地层的下降幅度就越大,对维持开挖面稳定的贡献越小。基于极限平衡法,提出了泥水盾构开挖面极限泥浆压力的计算方法,结果显示目前工程中采用的方法高估了开挖面极限泥浆压力。
[Abstract]:Mud film is the key factor to maintain the stability of dredging surface. The behavior of permeating mud into sandy soil and forming mud film on the surface of sand was studied by permeation column test. The relationship between permeability and time of mud membrane was obtained. The results show that the mud film can only be formed on the excavating surface because the cutter head is cutting the mud film continuously during the excavation, and when the pipe piece is assembled, the cutter head will stop turning, and the hard permeable mud film will be formed on the excavating surface. A two-dimensional numerical model of mud film with micro-permeable water on the excavated surface is established. The maximum pore pressure of soil is obtained by transient seepage analysis. According to the pore pressure of formation, the permeability in the unstable zone is calculated, and the distribution ratio between the mud film surface and the formation under different mud pressure is obtained. The larger the effective mud pressure, the greater the decrease of pore pressure outside the mud film and instability zone, and the smaller the contribution to the stability of the excavated surface. Based on the limit equilibrium method, a method for calculating the limit mud pressure of mud shield tunneling surface is proposed. The results show that the method used in current engineering overestimates the limit mud pressure of dredging surface.
【作者单位】：软弱土与环境土工教育部重点实验室(浙江大学);浙江大学岩土工程研究所;湖南大学土木工程学院;
【基金】：国家自然科学基金项目(51225804,U1234204,41472244) 教育部博士点基金项目(20120101110027)
【分类号】：U455.43

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