Key Design and Construction Technologies for PC Combined Cofferdam on Shallow-Buried Bare Rock Without Bottom Cover
The foundation of Piers 53#to 55#in the Weifang-Suqian High-Speed Railway Qiangkuang Reservoir superstruc-ture utilize dug-well foundations.At the pier locations,the maximum water depth reaches 6.6 meters,and the riverbed rock strata within the cofferdam consist of sandstone with virtually no overburden layer.For Pier 54#,the construction of the cap foundation employs a combined cofferdam system of steel pipe piles and steel sheet piles.Considering the construction charac-teristics of unlined cofferdams on shallow-buried bare rock without bottom covers,the deformation and stress conditions of the cofferdam system under various working conditions were analyzed through modeling.The analysis demonstrates that the struc-tural integrity and overall stability of the cofferdam are secure.Constructing unlined PC combined cofferdams using steel pipe piles and steel sheet piles presents significant challenges.This study introduces key construction techniques such as milling grooves,pile sinking,silt removal within foundation trenches,and the pouring of column base anchorage.The on-site imple-mentation of these techniques yielded favorable results,ensuring the successful and safe construction of the cofferdam system.
bare rock shallow burialno bottom coverPC combined cofferdamstructural designmilling groovecolumn base anchorageconcreting
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