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由于载体桩首次应用于高速铁路正线段深厚松软土地基加固,为了解其加固机理,开展了现场试验研究。通过对重型动力触探检测结果的对比分析发现,经载体桩加固后的桩端扩大头附近土体的挤密效果显著,其中扩大头位置处土体的N63.5提高了1倍。通过对试验段沉降变形的长期监测得出:监测结束时,试验段工后沉降为8mm,满足高速铁路要求;由于载体桩桩长短、桩体刚度大及桩端扩大头形成的端阻大,使得载体桩加固区的土体变形量较小,仅为8mm,不到总沉降量(100mm)的1/10。结合现场试验,提出了载体桩复合地基在高速铁路地基加固中的作用模型,为今后高速铁路载体桩的设计、施工和监测提供参考。
Because of the first application of the carrier pile to the foundation of deep and soft soil on the high-speed railway line, in order to understand its reinforcement mechanism, a field test was carried out. Through the comparison of the results of heavy-duty dynamic penetration test, it is found that the effect of compaction of the soil near the pile-end enlarged head is significant, and the N63.5 of the soil at the enlarged head position is doubled. Through the long-term monitoring of the settlement of deformation in the test section, the conclusion is obtained that the post-construction settlement of the test section is 8mm, which meets the requirements of the high-speed railway. At the end of the monitoring, the terminal resistance due to the length of the pile, The deformation of soil mass in the reinforcement area of carrier pile is small, only 8mm, less than 1/10 of the total settlement (100mm). Combined with the field test, the model of the effect of the composite foundation with the carrier pile in the reinforcement of the high-speed railway foundation is proposed, which provides a reference for the design, construction and monitoring of the carrier pile in the high-speed railway in the future.