海相软土地区铁路深长双向搅拌桩复合地基加固效果分析

针对18 m以上深长双向搅拌桩复合地基加固海相软土地区铁路路基的长期加固效果问题,依托新建青连铁路连盐试验段进行了现场试验研究。通过施工期的工艺优化和成桩质量控制,填筑期的荷载传递规律分析,以及贯穿施工期到运营期的长期沉降观测,验证了深长双向搅拌桩复合地基加固的长期可靠性。结果表明:干法和湿法双向搅拌桩加固苏北地区含水量在37%~55%之间的海相深厚软土地层具有可行性,试验桩长20 m范围内成桩质量良好;从施工期到运营期的路基沉降控制效果良好,满足规范对沉降的要求。试验研究成果拓展了双向搅拌桩的适用范围,在加固深度方面突破了现行规范规定的干法桩不宜大于15 m、湿法桩不宜大于18 m的限制,并且具有较好的经济效益和社会效益。

Analysis of Reinforcement Effect of Railway Deep-long Two-way Mixing Pile Composite Foundation in Marine Soft Soil Area

Aiming at the problem of long-term reinforcement effect of railway subgrade in marine soft soil area reinforced by composite foundation with two-way mixing piles with a depth of more than 18 m,field test research was carried out based on the newly-built Qinglian Railway Lianyan test section.Through process optimization and pile quality control during the construction period,the analysis of the load transfer law during the filling period,and the long-term settlement observation throughout the construction period to the operation period,the long-term reliability of the deep and long bidirectional mixing pile composite foundation reinforcement was verified.The results show that it is feasible for dry and wet two-way mixing piles to reinforce the deep and thick soft soil layers in the northern Jiangsu area with water content between 37% and 55%.The pile quality is good within 20 m of the test pile length;from construction period to operation period,the settlement control effect of the roadbed is good,and it meets the requirements of the regulations for settlement.The experimental research results have expanded the scope of application of two-way mixing piles,breaking through the limitations of the current code that dry piles should not be larger than 15 m and wet piles should not be larger than 18 m,and have good economic and social benefits.