施工参数对盾构穿越软土地层变形控制的影响分析

以盾构穿越昆明市轨道交通5号线金海新区站—福保站区间软土地层为背景,通过建立三维数值计算模型,研究施工参数对盾构穿越软土地层变形控制的影响。研究结果表明:双线盾构隧道施工,在相同施工工艺情况下,地层变形不完全对称;先掘进隧道由于开挖卸载作用,对地层原始应力产生影响,最终会产生略大于后掘进隧道的变形;盾构在软土地层中掘进,土仓压力宜略大于土体掌子面压力,即采用盈压模式掘进;盾构施工过程中,宜采用早凝浆液,同时宜使用稠浆,避免后期浆液凝固失水收缩产生地层损失,或采取其他措施达到及时填充盾尾空隙且无后期收缩作用的效果。

Infl uence of construction parameters on deformation control of shield tunneling through soft soil stratum

Based on the background of shield passing through the soft soil stratum between Jinhai New Area Station and Fubao Station of Kunming urban rail transit line 5,this paper studies the influence of construction parameters on the deformation control of shield passing through the soft soil stratum by establishing a three-dimensional numerical calculation model.The research results show that in the construction of double line shield tunnel,with the same construction technology,the stratum deformation is not completely identical and symmetrical,due to the excavation unloading effect,the original stress of the stratum is affected,and the deformation eventually is slightly greater than that of the later excavation tunnel.When the shield tunneling in soft soil stratum,the earth chamber pressure should be slightly greater than the soil body face pressure,that is,the surplus pressure mode is used in the process of shield construction.Early setting slurry and thick slurry should be used to avoid the formation loss caused by water loss and shrinkage in the later stage of slurry solidifi cation,or other measures should be taken to fill the gap at shield tail in time without later stage shrinkage.