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为了给盾构机在砂卵石地层中安全顺利的掘进提供参考,针对砂卵石地层中土压盾构掘进时开挖面稳定性难以控制、泥水盾构渣土排出困难的情况,提出一种使用泥膜支护开挖面,并使用螺旋排土器进行排土的新型盾构施工方法。考虑泥浆掺加量对泥浆砂卵石混合土在地层中的渗透及支护应力传递模式的影响,进行了不同泥浆掺加量下泥浆砂卵石土的渗透试验研究。在自制的渗透试验装置中,对6组不同泥浆掺加量的泥浆砂卵石混合土进行渗透试验,通过测定压力作用下地层及混合土中超静孔隙水压力及滤水量变化,分析泥浆砂卵石混合土的支护应力传递模式,讨论泥膜支护土压盾构的泥浆掺加量范围。结果表明:随着泥浆掺加量的增加,地层中的超静孔隙水压力消散速率在增加;存在3种应力传递模式,分别是孔隙水压力型传递、泥皮加渗透带型泥膜传递以及泥皮型泥膜传递;泥浆掺加量为23%~25%时可以实现泥膜支护。
In order to provide a reference for safe and smooth tunneling in sand-gravel stratum, in view of the difficulty in controlling the stability of excavation face during the excavation of earth pressure shield tunnel in sand-gravel stratum and the difficulty of discharge of shield muddy soil, A new type of shield construction method using mud film support excavation face and using spiral loosening device for soil drainage. Considering the effect of mud mixing on the permeability of mud-sand-pebble mixed soil into the formation and the stress-transmission mode of support, the infiltration experiments of mud-sand and pebble-bearing soil with different amounts of mud were carried out. In the self-made infiltration test device, six groups of mud mixed with different sizes of mud mixed with sand and sand were tested for infiltration. By measuring the change of excess pore water pressure and the amount of water in the stratum and mixed soil under pressure, Soil supporting stress transfer mode to discuss the range of slurry mixing mud pressure supporting shield. The results show that the dissipation rate of excess pore water pressure in the formation increases with the increase of mud mixing amount. There are three modes of stress transfer, namely pore-water pressure transfer, mud-permeable belt-type mud film transfer and Mud-type mud film transfer; mud mixing amount of 23% to 25% mud support can be achieved.