盾构下穿既有桩基磨桩施工关键技术

Key Technologies for Grinding Existing Pile Foundations under Shield Machines

摘要:

以上海轨道交通13号线东延伸工程为依托，针对盾构区间下穿既有厂房群桩过程中存在的桩基数量多、分布密集、基础资料不完整及软土地层条件复杂等施工难点，系统研究并总结了盾构下穿既有桩基磨桩施工的关键技术。结合工程实践，提出并实施了既有桩基多源判识与风险分级、磨桩前工程条件构建、盾构设备及刀具系统适应性配置、施工参数精细化控制以及全过程监测与动态风险控制等技术措施。工程中成功磨除既有桩基68根（上行线35根、下行线33根），实现了盾构姿态稳定、地表及周边构筑物变形可控。工程效果表明，地表沉降整体受控，既有建筑最大沉降为-3.7 mm，未发生结构性损伤。该技术体系有效降低了盾构下穿既有桩基施工风险，可为类似城市轨道交通工程提供参考。

Abstract:

Taking the east extension project of Shanghai Metro Line 13 as the background, aiming at the construction difficulties such as a large number of pile foundations, dense distribution, incomplete basic data and complex soft soil layer conditions that exist during the shield tunneling process of passing under the existing factory building group piles, the key technologies for grinding piles under existing pile foundations by shield machines are systematically studied and summarized. Combined with the engineering practice, the technical measures such as multi-source identification and risk classification of existing pile foundations, construction of engineering conditions before pile grinding, adaptive configuration of shield equipment and tool systems, refined control of construction parameters, and full-process monitoring and dynamic risk control are proposed and implemented. During the project, 68 existing pile foundations (35 on the upward line and 33 on the downward line) are successfully grinded off, achieving stable shield posture and controllable deformation of surface and surrounding structures. The engineering results show that the surface settlement is generally controlled. The maximum settlement of the existing buildings is -3.7 mm without structural damage. This technical system effectively reduces the construction risks of shield machines passing under existing pile foundations and can provide a reference for similar urban rail transit projects.