独墅湖第二通道工程关键技术研究

Research on Key Technology of Dushu Lake Second Channel Project

独墅湖第二通道工程陆域段采用明挖法施工,水域段采用明筑围堰法施工,总体道路方案的确定主要受规划、航评、洪评等因素影响。对于陆域段隧道,基坑邻近周边敏感建筑段主要采用刚度较大的地连墙支护形式,基坑底部进行了被动区加固,并针对性地采用了MJS、钻孔灌注桩的隔离措施。为了降低水域段隧道变形缝处的渗漏水隐患,在变形缝处采用了“桩基+枕梁”方案,通过减小差异沉降确保止水带的工作性能。对于水域段,采取双排钢管桩为主的围堰形式,根据航评、洪评结论采用分区施工的方案,以满足施工期间航道的正常通行和防洪要求。针对横向围堰的结构整体稳定性和抗渗流稳定性采取了相应措施,最后对基坑、围堰相互影响进行了分析研究,确保两者的安全。经过工程实践检验,以上关键技术合理可行,为类似工程提供了可借鉴的经验。

The land section of Dushu Lake Second Channel Project is constructed by the excavation method, and its water section is constructed by the open-built cofferdam method. The determination of the overall road scheme is mainly affected by the planning, navigation assessment and flood assessment. For the land section tunnel, the larger-rigidity underground diaphragm wall supporting form is mainly adopted for the foundation pit adjacent to the surrounding sensitive buildings, and the bottom of the foundation pit is reinforced in the passive zone. The isolation measures of MJS and cast-in-situ pile are adopted pertinently. In order to reduce the hidden danger of water leakage at the deformation joint of the water-section tunnel, the scheme of pile foundation + sleeper beam is adopted at the deformation joint to ensure the performance of the water stop belt by decreasing the differential settlement. For the water section, the cofferdam with the double-row steel pipe piles is adopted. The zoning construction scheme is adopted according to the conclusions of navigation and flood assessments to meet the normal navigation and flood control requirements during the construction. The corresponding measures are taken for the overall stability and the anti-seepage stability of the transverse cofferdam structure. Finally, the mutual influence of foundation pit and cofferdam is analyzed and studied to ensure the both safety. Through the engineering practice inspection, the above key technologies are reasonable and feasible. The referential experience can be provided for the similar projects.