PHC桩桩端改进后的沉桩与承载力探讨

PHC桩在沉桩过程中受土层特性和桩长的影响较大,随着桩长的增加,在中密~密实的砂性土层中沉桩的难度会加大.根据2个沿江电厂的桩基工程实例,在57 m长的PHC桩施工时采用了钢板环进行桩端处理,结合静载荷试验与高应变测试成果,对桩端改进型PHC桩的沉桩参数和承载力作了对比分析,试桩及工程桩的施工、试验与检测结果表明,采用钢板环处理的PHC桩,不但有利于沉桩施工,而且单桩承载力基本不受桩端改进措施的影响.通过探讨,为类似工程的桩基设计与施工积累了有益的经验.

Discussion on pile-driven and bearing capacity of PHC pile with improved bottom

PHC-pile(pretensioned spun high strength concrete pile) is greatly influenced by soil character and pile length in the process of pile-driven;and the difficulty of pile-driven will increase along with the pile length in medium-density to density sandy soils.According to the instance of pile project in two riverside plants where the pile bottom was strengthened by plate-steel annulus with length of 57 m in the process of pile-driven,the pile-driven parameters and bearing capacity of PHC pile with improved bottom are analyzed based on the result of statistic load test and high-strain test.The results of construction,experiment and test in the trial pile and project pile show that PHC pile,treated by plate-steel annulus,not only will be in favor of pile-driven construction,the bearing capacity of single pile wouldn't be influenced by the measure of improved pile-bottom.Finally some useful experiences are summed up for the pile design and construction in the similar projects.