深层淤泥竖向抽真空技术在防管桩突沉方面的技术应用

地基基础施工通常会遇到地下土层中含有淤泥、粉质黏土,大部分处于饱和、流塑状态,并且项目工程桩基础设计长度较长时,前期的排水固结法对深层淤泥的处理很难以起到作用,管桩突沉现象对工程桩施工质量安全影响严重。采用深层淤泥竖向抽真空技术,结合信息化建模能够解决管桩突沉问题。本文结合西湖湿地国际花园项目实例进行论述,介绍管桩突沉防控的实践应用,对类似工程有重要的参考价值。

流塑淤泥质土地质条件下PHC静压管桩防挤施工技术

在PHC管桩的静压方式施工作业过程中,由于挤土效应对先施工的压桩造成偏移或者起隆等现象,需要做纠偏、复压等工作,其工作量以及该过程中废桩的材料损失,大约造成2.5%桩基工程造价成本的上升。因此,克服管桩静压方式施工作业进程中的挤压土对先施工压桩的不利作用,既能节约工程成本,也是工程质量的的实际需要。PHC静压管桩防挤是一个多因素影响的管控过程,尤其是在流塑淤泥质土地质条件下,其管桩挤压更明显。本文通过论述流塑淤泥质土地质条件下PHC静压管桩防挤施工的管控,在论述该管控技术先进性的基础上,阐述了流塑淤泥质土地质条件下PHC静压管桩防挤的具体措施及原理,并在某基地三期联合厂房-土建工程中得到成功应用,使得该工程基桩全部检测合格,一类桩率达到91%的同时,节省了大约3.48%桩基工程造价成本。

Leachate Control Technology Using H-Jointed Steel Pipe Sheet Piles with H-H Joints at Coastal Landfills

H-H joint of ＂H-jointed SPSP with H-H joint＂, which is made up of interlocking two H-steel sections of different sizes, is the one of SPSP＇s joint to improve the hydraulic conductivity. ＂H-H jointed SPSP with H-H joint＂ is expected to be applied to a vertical cutoff wall in coastal landfill sites. In H-jointed SPSP with H-H joint, the H-joint is completely imperviousness. H-H joint, however, is pervious at interlocked state because a gap of 8 to 11 mm is left between the interlocking flanges, therefore, a water interception treatment must be conducted to seal the gap. The water shielding treatment of H-H joint is executed by coating the gaps with a water-swelling sheet of paint before its installation. Then, hollow space is generated in H-H joint after treating by water-swelling sheet, and that space can be used effectively. This paper proposes leachate control technologies using H-H joint interior space of SPSP cutoff walls. The possibility of those technologies and hydraulic conductivity of H-jointed SPSP with H-H joints are demonstrated by conducting the hydraulic conductivity test.