深海区小型钻孔平台设计与应用

Design and Application of Small-Size Boring Platform over Deep Sea Area

金塘大桥非通航孔桥上部结构为主跨118 m的变截面预应力混凝土连续梁,118 m梁区位于海域冲刷槽处,水深25～35 m,水流速度快,设计桥墩基础为10根250～300 cm大直径变截面钻孔灌注桩。考虑经济性及各种不利影响因素,C31号桥墩钻孔桩施工平台以钢护筒为承重基础,辅助平台以临时钢管桩为承重基础,承重梁、分配梁采用型钢,面板采用钢板;采用打桩船插打钢护筒和临时钢管桩、现场人工焊接平联和斜撑、浮吊配合履带吊拼装平台上部结构的方法施工平台。实践表明,该方案施工质量优、进度快、效益好。

The superstructure of the non-navigable spans of the Jintang Bridge is of a prestressed concrete continuous girder with variable cross section and with main spans each 118 m.The 118-m span girder is located over the scouring trough in sea where the water is 25~35 m deep,the current flow is swift and the designed foundation for each pier supporting the girder is made up of 10 nos.of large diameter variable cross section bored piles of 250~300 cm.In consideration of the cost-saving and various unfavorable influential factors,at Pier No.C31,the steel casings are used as the load-bearing foundations for the construction platform of the bored piles,the temporary steel pipe piles are used as the load-bearing foundations for the auxiliary platform,the steel sectional steels are used for the load-bearing beams and distribution beams and the steel plates are used as the surface plates for the platform.The platform is constructed by the method that the steel casings and temporary steel pipe piles are inserted and driven by floating drivers.The lateral bracings and diagonal struts are manually welded in filed and the superstructure of the platform is assembled by the caterpillar crane by the aid of the floating drivers.Practice proves that the construction by the method as mentioned is of high quality,is fast and the economic benefit achieved therefrom is good.