福州地区深长PHC静压管桩的沉桩控制问题

Pile-driving controlment Problem of Deep-long Prestressed High-strength Tube-shaped Piles in Fuzhou Area

针对福州地区典型的工程地质条件,结合2个实际工程,在分析长桩受力特点及其压桩力与桩的承载力关系的基础上,利用工程试验和实测数据对深长PHC静压管桩的沉桩控制问题进行研究,主要结论如下:对长细比达60以上的长桩和超长桩,沉桩应以桩长控制为主,终压力控制为辅;桩长控制时,桩端持力层选择风化岩层上的残积土层或砂层即可,不必且不宜以风化岩层为桩端持力层;终压力通常达不到单桩极限承载力值,其控制值应视桩周土和桩端土的性质而定。

Aiming at the typical engineering geology condition, based on that the mechanics performance and relationslfip between end pressure and bearing capacity of long pile combining with two engineering projects the pile-driving controlment problems of deep-long prestressed high-strength concrete （PHC） tube-shaped piles are studied by appling the engineering tests data. The main conclusions are as follow： （1） when the length-diameter ratio of PHC piles surpasses sixty, pile-driving should take pile＇s length as the dominant factor and regard end conpression force as the auxiliary factor; （2） instead of weatherd rock, pile＇s length controlment should choose residual soil or sand upon weatherd rock as bearing stratum of pile-tip; （3） while the end compression force doesn＇t amount to the ultimate beating capacity of a pile usually, its controlment value depands on characteristics of soils bearing pile-shaft and pile-tip.