软弱不良地质顶管偏移机理

作者：祝彬 王德权 黄洋洋 张士民

单位：1 中铁上海工程局集团市政环保工程有限公司，上海 200436； 2 沈阳工业大学建筑与土木工程学院，沈阳 110870

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中文摘要：以南京凤台路泵站 - 长虹路段 WCO7-WCO6 顶管工程为研究对象，聚焦顶管施工中的管道轴线偏移问题，结合实 际监测数据与理论分析，探究其偏移机理，为施工控制提供支撑。该工程顶段长 220m，采用 Q235B 钢管顶进，位于河漫 滩地貌，穿越素填土、淤泥质粉质黏土及粉质黏土夹粉土等地层。其中，淤泥质粉质黏土流塑、高压缩性且具高灵敏度和 流变性，粉质黏土夹粉土存在薄层互层，地层稳定性差；地下水含孔隙潜水与承压水，与秦淮河地表水相通，雨季水位波 动可能影响施工，且水土对结构有一定腐蚀性。施工中，在机头后第一节及第六节管节中段设监测断面，各断面布环向与 轴向应变计监测受力。数据分析显示，顶管机头常向右上偏斜，部分管节顶进时偏斜较明显，最终尾节偏斜得到修正。管 节不同位置受力差异显著，呈现非对称性，机头遇木块、碎石等障碍物时偏斜加剧，经纠偏后改善。理论分析构建顶进面 轴线与管周环向受力模型，指出受力平衡打破是偏移核心。障碍物导致迎面阻力不均、管周摩阻力耦合效应及顶推力调节 滞后是关键机理，且动态调节顶推力可有效恢复平衡。本工程经验及理论成果为软弱地层顶管偏移控制提供了理论与实践 参考。

中文关键词：矩形顶管；分体始发；工作井，城市地下空间

英文摘要：Taking the WCO7-WCO6 pipe jacking project from Fengtai Road Pump Station to Changhong Road in Nanjing as the research object, this study focuses on the problem of pipeline axis deviation during pipe jacking construction. Combining actual monitoring data and theoretical analysis, the deviation mechanism is explored to provide support for construction control. The top section of the project is 220m long and is topped with Q235B steel pipes. It is located in a floodplain terrain, crossing through layers such as plain fill, silty clay, and silty clay mixed with silt. Among them, the silty clay has flow plasticity, high compressibility, high sensitivity, and rheologicalproperties. The silty clay interbedded with silt has thin layers and poor geological stability; Groundwater contains pore water and confined water, which are connected to the surface water of Qinhuai River. Fluctuations in water level during the rainy season may affect construction, and the soil and water have a certain degree of corrosiveness to the structure. During construction, monitoring sections are set up in the middle section of the first and sixth pipe sections behind the machine head, and circumferential and axial strain gauges are installed on each section to monitor the stress. Data analysis shows that the head of the top pipe often tilts upwards to the right, and some pipe sections deviate more significantly when pushed in. Finally, the tail section deviation is corrected. There is a significant difference in force distribution at different positions of the pipe joint, showing asymmetry. When the machine head encounters obstacles such as wooden blocks and crushed stones, the deviation intensifies, but it is improved after correction. Theoretical analysis constructs a force model for the axis of the jacking surface and the circumferential force of the pipe, and points out that breaking the force balance is the core of the offset. The key mechanisms are uneven frontal resistance caused by obstacles, coupled effects of circumferential frictional resistance, and delayed adjustment of top thrust, and dynamic adjustment of top thrust can effectively restore balance. The experience and theoretical achievements of this project provide theoretical and practical references for the control of pipe jacking offset in weak strata.

英文关键词：Rectangular top pipe; Split initiation; Working pit; Urban underground space