钻孔灌注桩水下混凝土浇注钢筋笼上浮事故分析与对策

水下混凝土浇注钢筋混凝土上浮事故的原因是操作不当，如钢筋笼固定不牢，提升导管过猛，导管埋深不当等，以及混凝土品质差，如坍落度，含砂率，粘聚性，初凝时间等不合要求，采用对策是保证灌注导管位于钢筋笼中心，控制导管埋深，灌注速度及提升导管的速度，配制品质好的混凝土，以及采用“倒刺”方法和专用品钩等预防措施。

ANALYSIS AND TREATMENT METHOD OF UNDERWATER CONCRETE KEINFORCING CAGE UP-FLOATING ACCIDENT IN BORED AND CAST INPLACE PILE

The cause of underwater concrete reinforcingcage up-floating accident is improper operation, such as loose-placement of reinforcingcage, fast-drawing of conduct pipe, improper embedded depth of conduct pipe; and the poorquality of concrete, for example, the slump, sand percentage, adhesiveness and initialsetting time don't meet requirement. The precautions for the underwater concretereinforcing cage up-floating accident is placing the reinforcing cage in the pile holecenter, controlling the embedded depth of conduct pile, concrete casting velocity andconduce pipe drawing velocity, mixing fine quality concrete, adding barbed bar andspecialized refincing cage hanger hook.