浅埋条件下盾构施工参数对地层扰动影响研究 ——以福州地铁4号线某路段区间盾构隧道施工为例

Study on the influence of shield construction parameters on strata disturbance under shallow buried conditions——Take the construction of a shield tunnel in a section of Fuzhou Metro Line 4 as an example

以福州地铁4号线化工路站~福新东路站区间盾构隧道穿越软土地层施工为背景,采用数值模拟方法,建立了考虑土仓压力、刀盘-土体摩擦扭矩、注浆压力、盾壳-土体摩擦力的盾构动态开挖模型,研究了浅埋条件下各施工因素对周围土体的扰动规律。结果表明:盾构开挖过程,在土仓压力和盾尾注浆压力等因素的综合作用下,开挖空间上方地层出现先隆起后沉降的变化过程,一侧土体则在盾构开挖过程逐渐外扩,沉降及水平位移最大值分别出现在开挖轴线的竖向和水平面上;土仓压力和盾尾注浆压力的增加有利于减小地层沉降值,但对应侧面土体水平位移有所增大,刀盘与盾壳和土体间摩擦力的增加会进一步增加上部地层沉降和侧面土体水平位移,施工过程应根据地层变形控制要求,合理调整土仓压力和盾尾注浆压力,同时降低机械与土体的摩擦。

Based on the construction of the shield tunnel crossing the soft soil layer between the Huagong road station and the Fuxin east road station of Fuzhou Metro Line 4,a shield dynamic excavation model was established with numerical simulation method considering cutter head friction,soil chamber pressure,grouting pressure,shield friction,and the disturbance law of various construction factors on the surrounding soil was studied.The results show that during the shield excavation,under the combined action of factors such as soil chamber pressure and grouting pressure,the strata above the excavation space appears to be deformed from uplift to settlement,and the soil on one side gradually expanded.The maximum settlement and horizontal displacement appear on the vertical and horizontal planes of the excavation axis,respectively.The increase of the soil chamber pressure and grouting pressure is beneficial to reduce the ground settlement,but the corresponding horizontal displacement of the lateral soil is increased.The increase of the cutter head friction and shield friction will further increase the settlement of upper stratum and the horizontal displacement of lateral soil.In the construction process,according to the requirements of stratum deformation control,the soil chamber pressure and grouting pressure l should be adjusted reasonably,and the friction between the machine and the soil should be reduced.