摘要:
针对深厚海相软土中螺旋钢管桩可能存在的桩体失稳及耐久性的问题,提出一种注浆螺旋钢管桩。设计了两阶段试验:第一阶段进行成桩工艺试验,以验证成桩工艺可行性,并为桩型设计及施工方案优化提供参考;第二阶段采用优化工艺成桩,通过单桩抗压承载力试验,得到了桩顶荷载-沉降位移曲线以及桩的典型破坏特征,并对套管和注浆方式对抗压极限承载力的影响做了进一步研究,分析注浆螺旋钢管桩桩土相互作用的特征。最后将试验实测结果与美国Hubbell能源限公司的计算手册及美国联邦公路管理局推荐的计算方法的计算结果进行对比。结果表明:螺旋叶片扩大了注浆体浆液固化体直径,套管提高了桩体稳定性,采用旋进注浆方式成桩能够显著提高桩基抗压承载力。
Abstract:
Aiming at the problems for instability and durability of halical steel pipe piles in deep marine soft soil, a helical steel grouting pipe pile was proposed. A two-stage test was designed. In the first stage, different tested piles were used for pile-forming tests to verify the feasibility of pile-forming processes. The influence of sleeves and grouting methods on pile-forming quality was analyzed, and the pile type design and the pile-forming process were optimized. In the second stage, the influence of sleaves and grouting methods on the ultimate bearing capacity of helical steel grounting pipe piles was studied by the compressive bearing capacity tests of improved single piles. The curves of loads and settlement displacement at pile tops and the typical failure characteristics of piles were obtained, and the variation characteristics of pile-soil interaction for helical steel grounting pipe piles were analyzed. Finally, the experimental results were compared with the calculation results by Chance@ Civil Construction: Technical Design Manual compiled by Hubbell Power Systems, Inc. and Micropile Design and Construction Reference Manual issued by Federal Highway Administration of America. The test results showed that the helical paddles expanded the diameters of cemented grouting slurry and sleeves could effectively enhance the stability of piles. The grouting effect was significant and the full-section rotary jet grouting method could significantly increase the bearing capacity of piles under vertical compression.