高速铁路载体桩复合地基加固机理的试验研究*
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（西南交通大学土木工程学院， 成都 610031）［摘要］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。［关键词］高速铁路; 软土地基; 载体桩; 重型动力触探; 沉降变形中图分类号：TU473 文献标识码：A 文章编号：1002-848X(2013)22-0073-04Experimental study of reinforcement mechanism of composite foundation using ram-compacted piles with bearing base in high-speed railwayChen Hongyun, Ma Jianlin, Yang Yanxin(School of Civil Engineering, Southwest Jiaotong University, Chengdu 610031, China)Abstract: Because ram-compacted piles with bearing base(RPBB) are adopted in the reinforcement of deep soft soil foundation on main line of high-speed railway for the first time, in-situ experiments were conducted to understand the reinforcement mechanism of RPBB. The comparison study for heavy dynamic penetration test results of the reinforcement before and after using RPBB indicates that the compacting effects of the soil around expanded pile end of RPBB are obvious, and value of the N63.5, which is used to evaluate the compacting effects, doubles after using RPBB. The long-term monitoring of settlement and deformation of the test section show that the post-construction settlement is 8mm which satisfies the requirement of high\|speed railway construction. The deformation of the reinforcing area is only 8mm, and it′s less than 10% of the total settlement (100mm) due to the short pile and the large column rigidity and the increase of the base resistance of the expanded pile end. A model of RPBB in foundation reinforcement is put forward based on the in-situ experiment results, providing reference for the design, construction and monitoring of high-speed railway in the future.Keywords: high-speed railway; soft soil ground; ram-compacted piles with bearing base; heavy dynamic penetration test; settlement and deformation*铁道部京沪高速铁路科技重大专项（2008G32-A）。作者简介：陈洪运，博士研究生，Email：278709407@qq.com。参考文献［1］王继忠. 载体桩技术的诞生与发展［J］. 建筑结构， 2008，38(4): 118-119.［2］王炳龙，周顺华，杨龙才. 高速铁路软土路基工后沉降试验研究［J］. 同济大学学报：自然科学版， 2003, 31(10): 1163-1167.［3］宋上明. 真空-堆载联合预压软基处理技术在铁路路基试验段的应用［J］. 铁道工程学报， 2010(1): 24-28, 37.［4］董亮，叶阳升，蔡德钩，等. 高速铁路软土地基处理方法对比试验［J］. 岩土力学， 2006, 27(10): 1856-1860.［5］任文峰，王星华，韩晓飞. 高速铁路软土路基沉降试验研究［J］. 水利与建筑工程学报， 2010, 8(4): 65-68.［6］李添翼. 浆喷桩地基控制高速铁路工后沉降的研究［J］. 铁道工程学报， 2012(11): 18-22.［7］赵勇，陈占，徐红星. 高速铁路无砟轨道路基沉降监测和研究［J］. 铁道工程学报， 2012(6): 45-49.［8］JGJ 135—2007 载体桩设计规程［S］.北京:中国建筑工业出版社, 2007.
