澳氹第四跨海大桥大直径钢套管沉桩施工关键技术  

Key Construction Techniques for Large-Diameter Steel Pipes of Bored Piles of Fourth Macao-Taipa Sea-Crossing Bridge

作　　者：陈宁贤 CHEN Ningxian(China Railway Construction Bridge Engineering Bureau Group Co.,Ltd.,Tianjin 300300,China)

机构地区：[1]中国铁建大桥工程局集团有限公司,天津300300

出　　处：《世界桥梁》2023年第6期41-47,共7页World Bridges

基　　金：中国铁建股份有限公司科研计划课题(2020-B1)。

摘　　要：澳氹第四跨海大桥主桥为大跨度钢箱加劲连续钢桁梁桥,主桥基础采用∅2.8 m钻孔灌注桩基础,最大孔深107 m,钢套管需穿过覆盖层、全风化及强风化花岗岩,嵌入持力层中风化花岗岩至少0.3 m。桩基础施工时,首先采用ZRT320H型全回转钻机配合SWDM550型旋挖钻机取土沉放钢套管至中风化岩面,然后采用反循环钻机(RCD)磨岩成孔,最后清水清孔、灌注水下混凝土成桩。钢套管由筒身、底节、合金刀齿三部分组成,首节长19.5 m,按照桩长配置12.0 m标准节段。钢套管入土小于50 m时,在全回转钻机底座四角焊接限位板定位锚固;入土深度超过50 m后,通过传力杆和锚座进行定位锚固。采用旋挖钻机配备专用取芯钻头或反循环钻机等工艺措施处理孤石。主桥全部钢套管在沉桩施工中,未发生屈曲变形和卷边等现象。The main bridge of the Fourth Macao-Taipa Sea-crossing Bridge is a long-span continuous truss girder bridge.The piers are supported on the foundations formed of 2.8 m-diameter bored piles,where the maximum depth of the borehole reaches 107 m,the piles must pass through the overburden,completely decomposed and highly decomposed granite and root at least 0.3 m into the bearing stratum of moderately decomposed granite.During the pile foundation construction,the full slewing drill ZRT320H and rotary drilling rig SWDM550 were used to excavate to allow the steel casings to sink into the moderately decomposed rock,afterwards,the reverse circulation drill was employed to grind the rock for hole formation.Subsequently,the borehole was cleared up using clean water,and the tremie concrete was poured to form a pile.A steel casing consists of the shaft,bottom lift and alloy bits.The first lift of the steel casing measured 19.5 m,considering the pile length,a typical segment of 12.0 m was needed.When the inserting depth of the steel pipe is less than 50 m,limiters were welded to the four corners of the pedestal of the full slewing drill to position and anchor the drill.When the inserting depth of the steel pipe exceeds 50 m,the full slewing drill was anchored via force transfer rods and anchor saddles.The rotary drilling rig was used together with the specialist coring bit or reverse circulation drill to treat the isolated rocks.No buckling or edge curling was observed during the sinking of the steel casing.

关 键 词：跨海桥梁 钻孔灌注桩 大直径钢套管 全回转钻机 旋挖钻机 沉桩技术 孤石处理 

分 类 号：U443.15[建筑科学—桥梁与隧道工程] U445.4[交通运输工程—道路与铁道工程]