水泥改良粉细砂路基工后沉降及空间应力分布研究

Study on Post Construction Settlement and Spatial Stress Distribution of Fine Silty Sand Subgrade Improved by Cement

依托浩吉铁路路基工程,探讨粉细砂路基的工程灾害机理,并通过掺加水泥改良其压实性能,对改良的粉细砂路基内部的变形和竖向应力进行监测,分析了沉降及其空间应力分布特征。结果表明:粉细砂路堤存在压实性欠佳、振动强度衰减及边坡易失稳等问题,通过掺加水泥可以提高其压实性能,其水泥/粉细砂的最优配比为5%;竖向沉降随深度的增加总体上逐渐降低;竖向应力随时间变化不大,且随着深度增加总体上逐渐增大,除基床表层以外,基床底层和基床以下路堤区域均低于理论自重应力值;水平方向,对称位置处竖向应力差异较大,揭示了路基内部应力分布复杂的不均匀特征。

Depending on the subgrade engineering at Haolebaoji-Ji an Railway,the engineering disaster mechanism of fine silty sand subgrade was discussed.Where the compaction performance of fine silty sand subgrade was improved by cement,the internal deformation and vertical stress of the improved subgrade were monitored,and then the settlement and spatial stress distribution characteristics were analyzed.The result shows that,for the fine silty sand embankment,there are some issues,such as poor compactability,attenuated vibration strength and slope prone to failure,wherein the compactability may be improved by cement with the optimal proportioning of cement to fine silty sand being 5%;generally,as the depth increases,the vertical subsidence decreases gradually,and the vertical stress increases gradually,but changes little over time,and besides the surface layer of subgrade bed,at the bottom layer and in the embankment area beneath the bed falls below the theoretical value of gravity stress;at the horizontal direction,the vertical stresses at symmetrical positions are quite different,which discloses the complex characteristics of uneven stress distribution inside the subgrade.