软土地区轨道交通桥梁下方灌注桩小净距施工影响
朱兆斌
Impact of Small Clearance Bored Pile Construction under Rail Transit Bridges in Soft Soil Area
ZHU Zhaobin
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作者信息:杭州铁路设计院有限责任公司，310043，杭州
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Affiliation:Hangzhou Railway Design Institute Co., Ltd., 310043, Hang-zhou, China
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关键词:
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Key words:
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DOI:10.16037/j.1007-869x.2024.07.026
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中图分类号/CLCN:U443.15
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栏目/Col:研究报告
摘要:
［目的］我国沿海软土地区灌注桩与运营轨道交通桥梁、桥墩间小净距的施工影响正成为制约城市轨道交通规划与建设的又一瓶颈因素，因此有必要研究小净距钻孔灌注桩施工对周围地层和桥墩的变形影响。［方法］以浙江某城市道路桩板结构形式下穿轨道交通桥梁在建工程为例，通过设计土体侧向变形监测试验和搭建既有桥梁、桥墩的位移智能监测系统，分析了深厚软土区地层与测斜孔的协同变形特性，以及钻孔灌注桩施工对周围地层及桥墩变形的影响规律。［结果及结论］为使测斜孔与地层具有较好的协同变形，软土区测斜孔施工后应稳定停留6d；淤泥层对施工加载、卸载过程的敏感性较高，由施工引发的软土地层变形量最大；在施工条件下，桥墩3个方向的变形幅值约为未施工的2~3倍；成孔开挖和混凝土浇筑工序对桥墩深度方向的扰动影响较显著，因此已运营轨道交通桥梁下部施工的监测重点应为竖向位移。
Abstracts:
［Objective］ The impact of small clearance construction between bored piles and piers of operational rail transit bridges in China′s coastal soft soil areas is becoming a bottleneck factor restricting urban rail transit planning and construction. Therefore, it is necessary to study the impact of small clearance bored pile construction on the deformation of surrounding strata and bridge piers. ［Method］ Taking an ongoing project of urban road pile-slab structure under passing the rail transit bridge in Zhejiang Prov. as example, through designing soil lateral deformation monitoring tests and building a displacement smart monitoring system for bridge and piers, the coordinated deformation characteristics between deep soft soil strata and inclinometer boreholes are analyzed, together with the impact law of bored pile construction on the deformation of surrounding strata and bridge piers. ［Result & Conclusion］ To ensure good coordination in deformation between inclinometer boreholes and strata, inclinometer boreholes in soft soil areas should remain for 6 days after the completion of construction. The sensitivity of the silt layer to the construction loading and unloading process is high, resulting in the maximum deformation of soft soil strata induced by construction. Under construction conditions, the deformation amplitude of the bridge piers in three directions is about 2 to 3 times that of non-construction conditions. The drilling excavation process and concrete pouring process have a significant disturbance effect on the depth direction of bridge piers. Therefore, the monitoring focus of construction beneath operational rail transit bridges should be put on vertical displacement.
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