公路黄土地基处治前后沉降变形分析

在湿陷性黄土地区,黄土作为高速公路地基的主要原料其强度和变形特性不能满足要求,主要有振动碾压、冲击碾压和强夯3种有效且实用的处治方法。本文根据原位试验和室内试验的数据,进行有限元模拟,在不同高度路堤和不同加载方式情况下,地基沉降变形随着处治能级的增加而减小,路堤本身的沉降保持不变。对于地基处理的深度和沉降变形减小的效果,强夯最好,冲碾次之,振碾最弱。处治前后地表中心沉降变形值与加载路堤高度之间的关系均可用二阶多项式回归拟合。2～4m高的路堤采用振碾的方式处理地基,5～10m高的路堤采用冲碾方法,大于10m的路堤多用强夯或者直接修桥来代替,对于黄土地区高速公路建设与维护具有重要意义。

SETTLEMENT AND DEFORMATION ANALYSES BEFORE OR AFTER TREATMENT ON EXPRESSWAY LOESS FOUNDATION

In the collapsible loess area,it can't meet the need of strength and deformation characteristic while loess as the main raw material of expressway subgrade.There are three effective and applied treatment methods:vibrating roller compaction,rolling dynamic compaction,and dynamic compaction.According to data from test in situ and indoor test,going along finite element simulation,it concludes that foundation deformation decreases along with the increase treatment energy,embankment self deformation keeps steady.To the treatment depth and deformation minishing effect,the best is the dynamic compaction.The rolling dynamic compaction takes second place.The last is the vibrating roller compaction.Quadratic polynomial regression is used to analyze the correlations between the settlement and deformation of foundation surface center and different road embankment heights.The vibrating roller compaction treatment technology benefits for embankment height 2~4 meters.The rolling dynamic compaction treatment technology suits for embankment height 5~10 meters.The height over 10 meters usually be treated with the dynamic compaction or directly make use of bridge to instead of.It is significant to expressway subgrade construction and safeguard in loess area.