挤密桩处理湿陷性黄土路基的效果研究

黄土由于其湿陷性的特殊性质,导致铁路路基出现不均匀沉降,从而影响铁路安全。本文依托湿陷性黄土路基工程背景,建立三维数值模型,对挤密桩处理湿陷性黄土路基效果进行研究。结果表明:挤密桩桩径对挤密水平范围有显著影响,挤密影响范围可分为充分挤密区、有效挤密区和挤密影响区。桩周土体竖向位移随距桩边距离的增大先迅速增大随后逐渐减小直至为0,在距离桩边约0.7~1.0 D处,竖向位移达到峰值;竖向位移随深度增加而逐渐减小,当深度约为2 m(0.4倍桩长)时土体几乎无竖向位移,随后竖向位移继续增大。一定范围内增大挤密桩直径能显著扩大挤密影响区。依据分析结果得出依托工程最经济、合理的挤密桩直径为0.4 m;根据现场监测数据,路堤施工完毕后路基整体累计沉降量不超过5 mm,满足规范要求,说明灰土挤密桩处理湿陷性黄土路基效果良好。

Effect of Lime Soil Compaction Pile in Treating Collapsible Loess Subgrade

Due to the special nature of loess collapsibility,uneven settlement of railway subgrade occurs,which affects railway safety.Based on the engineering background of collapsible loess subgrade,this paper established a three-dimensional numerical model to study the treatment effect of collapsible loess subgrade with compaction pile.The results show that the pile diameter of compaction pile has a significant influence on the compaction level range,and the compaction influence range can be divided into full compaction area,effective compaction area and compaction influence area.With the increase of the distance from the pile edge,the vertical displacement of soil around the pile first increases rapidly,and then decreases gradually until it is 0.The vertical displacement reaches the peak at about 0.7 d~1.0 D from the pile edge.The vertical displacement gradually decreases with the increase of depth.When the depth is about 2 m(0.4 times the pile length),the soil has almost no vertical displacement,and then the vertical displacement continues to increase.Increasing the diameter of compaction pile in a certain range can significantly expand the compaction affected area.According to the analysis results,the most economical and reasonable compaction pile diameter of the project is 0.4 m.Based on the site monitoring data,after the completion of embankment construction,the overall cumulative settlement of the subgrade shall not exceed 5 mm,which meets the specification requirements,indicating that the lime soil compaction pile has a good effect in treating the collapsible loess subgrade.