拓宽加载对旧路基附加沉降影响数值分析

Numerical Analysis of Additional Settlement in Existing Roadbed Produced by Roadbed Widening

基于有限元数值分析方法,对路基拓宽工程中,新路基填筑对旧路基附加沉降的影响进行了研究。选取6 m厚软土地基双向4车道的两侧拓宽工程作为数值模拟原型,新路基填筑分别采用不同的填筑、固结间隔期的分层加载方式,通过监视旧路基坡趾下方不同深度的指定观察点,提取观察点的沉降-时间曲线,分析其加载过程的沉降特征,获取不同拓宽加载方式下旧路基下地基影响深度范围内附加沉降的变化特点及沉降完成时间。研究结果表明,新路堤填筑加载总量一定时,不同填筑方式引起的旧路堤附加沉降基本为定值,根据堆载高度可以确定旧路基最终沉降量;新路堤填筑方式影响旧路堤的沉降完成时间、填筑加载时间与自然固结时间相对集中时,旧路堤完成沉降所需工期较短。

The additional settlement in existing roadbed generated by roadbed widening was studied based on finite element method （FEM） . A two-side widening engineering in a bidirectional and four-lane highway with 6 m thickness soft soil ground was selected as the numerical analysis model. Two kinds of multi stage construction condition were chosen to simulate the process of roadbed fill in widened parts with different time intervals and consolidation. The behavior of soft soil ground settlement in the process of roadbed widening were analyzed according to the settlement-time （s-t） curves produced by monitoring the specified points with different depths under the slope too of existing roadbed, which revealed the diversification properties of additional settlement in the soft soil ground and its continuance time in the whole process. Analysis results show that （1） the filling approach of widening roadbed affects mainly to the continuance time of additional settlement in existing roadbed but little to magnitude, which may serve to minish the construction time if the works of roadbed filling and soft soil ground consolidation are respectively arranged in relatively centralized periods; （2） the final magnitude of additional settlement can be obtained according to the filling thickness of widening roadbed.