盾构穿越既有桥梁桩基磨桩技术的研究
Grinding pile technology of shield tunnels crosssing pile foundation of existing bridges
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摘要: 基于杭州地铁2号线建国路站—中河路站区间盾构穿越凤起桥6根大直径桥桩工程需要,根据软土地区及大直径桩基特点进行刀具选型,结合Advant Edge FEM有限元软件对贝壳刀的角度进行设计,并对刀具布置方式进行研究。研究结果表明:双面刃、零后角、负前角组成的贝壳刀,结合先行刀与刮刀,采用同心圆三段高差立体刀具布置切削桩基效果最佳。将结果应用到盾构刀盘改进,配合盾构推进过程中的施工控制,对桥面进行沉降监测。监测结果表明:盾构磨桩过河区间中桥面平均累计沉降仅-3.09 mm,未对凤起桥及河流产生明显影响,切削钢筋效果较好且只有极少部分钢筋缠绕在刀具上。此项技术成功应用于杭州地铁2号线凤起桥磨桩工程,可为今后类似磨桩工程提供借鉴。Abstract: Based on the construction requirements of the shield tunnel crossing 6 large-diameter bridge piles of Fengqi bridge in the section of Jianguo Road Station-Zhonghe Road Station of Hangzhou Metro Line 2, the cutter type is selected according to the characteristics of soft soils and large-diameter piles. The angle of shell cutter is designed by the Advant Edge FEM finite element software, and the arrangement of the cutter layout is studied. The results show that for the shell cutter composed of double edges, zero back angle and negative front angle and combined with advance cutter and scraper, the layout of the concentric circle with three-section height difference and three-dimensional cutter is the most effective in cutting piles. Then the results are applied to the improvement of shield cutter head. The settlement of bridge deck is monitored during the shield driving process. The monitoring results show that the cumulative settlement of bridge deck in the cross-river section during shield grinding piles is only -3.09 mm, which has no obvious influence on the Fengqi bridge and river. The cutting steel bar is effective except that the cutter is worn on a few parts. This technology has been successfully applied to the grinding piles of Fengqi bridge of Hangzhou Metro Line 2, which may provide insights for the similar grinding pile projects.