CFG桩复合地基处理软弱路基沉降机理

Treatment of settlement of soft road groundwork with CFG column composite foundation

结合兰永一级公路软弱路基处理技术研究项目,分析CFG桩复合地基处理软土路基的沉降机理.利用非线性有限元软件ADINA,建立三维模型,结合比奥固结理论,地基土体按多孔介质材料考虑,采用Mohr-Coulomb理想弹塑性模型做固结分析,将填土视为荷载逐级施加,采用生死单元对CFG桩复合地基进行数值模拟.结果表明,CFG桩复合地基处理软土路基沉降随着路堤填土高度的逐层增加而增大;随着时间的推移,沉降量前期不断增加,在工后300d左右沉降量增加缓慢,最终趋于稳定;满足一级公路工后沉降要求,地基土中超孔隙水压随填土高度的增加不断增大,在工后逐渐消散,加固效果明显.

In connection with the investigation project of soft roadbed treatment technique of Lanyong highway, the mechanism of settlement treatment of soft soil roadbed with CFG pile composite foundation is analyzed. By using nonlinear finite element software ADINA, a three-dimensional model is established. By employing Blot consolidation theory and considering foundation soil as porous medium material, its consolidation analysis is conducted by using Mohr-Coulomb elastic-plastic model, where the soil filling is regarded as load applied step by step, and birth-and-death element is used to simulate the CFG composite foundation. The results indicate that the settlement of CFG pile composite foundation increases with the height of embankment fill applied step by step. As time goes on, settlement height in its earlier stage in- creases continuously and increases slowly during 300-day post-construction period, and eventually tends to be stable, satisfying the requirements of post-construction highway of class-1. The pore pressure increases with the filling step by step, and dissipates gradually in post-construction period. The reinforcement effect is obvious.