钻孔灌注桩施工对邻近运营隧道变形影响研究

桩基施工将引起周边地层位移和邻近隧道结构变形,以南京龙津桥改建项目桩基工程为背景,通过现场实测,分析研究钻孔灌注桩施工全过程各工况条件对地层位移场和邻近既有隧道结构变形的影响规律。结果表明:由于钢套管的护壁作用,钻孔灌注桩施工过程中产生的最大地层位移和隧道结构变形较小,说明采用“钢套管边旋压边取土”、“群桩间跳施工”等工艺,对周围土体扰动影响程度较小,建议近隧桩基工程采用全套管灌注桩的施工方法,监测分析结果可为类似工程提供技术参考。

Impact of Bored Pile Construction on Deformation of Adjacent Operating Tunnel

Pile foundation construction leads to surrounding strata displacement and adjacent tunnel structural deformation.Based on Nanjing Longjin Bridge Reconstruction Project,field monitoring was used to analyze the impact of various operating conditions on the strata displacement and structural deformation of adjacent tunnel during the bored pile construction.The results show that the maximum strata displacement and tunnel structural deformation are small during the construction of bored pile due to the effect of steel casing,which indicates that the technologies such as removing the soil while spinning steel casing and interval construction have little influence on the disturbance of surrounding soil.It is suggested that the construction method of full casing cast-in-place pile should be adopted in the near-tunnel pile foundation project.The monitoring and analysis results can provide technical reference for similar projects.