路堤荷载下短混凝土芯碎石桩复合地基的固结特性

Consolidation Behavior of Composite Ground with Short Concrete-core Stone Columns Under Embankment Loading

为研究短混凝土芯碎石(SCCS)桩复合地基的固结特性,建立轴对称有限元模型,模拟分析路堤荷载下端承和悬浮SCCS桩复合地基的固结速率并与单一材料的碎石桩复合地基和混凝土桩复合地基进行比较。通过参数分析,研究主要影响因素的变化对端承和悬浮SCCS桩复合地基固结速率的影响。结果表明:无论SCCS桩是否打穿软土,SCCS桩复合地基的固结速率与相应的碎石桩复合地基几乎相同,远大于混凝土桩复合地基。端承SCCS桩复合地基的固结速率大于悬浮SCCS桩复合地基。悬浮SCCS桩复合地基的固结速率主要取决于SCCS桩贯入比,贯入比越大,复合地基固结越快。端承SCCS桩复合地基的固结速率主要取决于芯桩的刚度,芯长较大时它随芯桩模量的增加而逐渐增大。其他因素对端承和悬浮SCCS桩复合地基固结速率影响很小,可以忽略。

In order to analyze the consolidation behavior of the composite ground with short concrete-core stone(SCCS)columns,an axisymmetric finite element model is established in this paper.The consolidation rates of the soft ground improved by end-bearing SCCS columns and floating SCCS columns under embankment loading are simulated numerically.Two soft foundations improved by stone columns and concrete piles are analyzed for comparison purposes.A parametric study is conducted to evaluate the influence of some main factors on consolidation rates of the composite ground with end-bearing SCCS columns and floating SCCS columns.The results show that whether SCCS columns penetrate fully into soft soil or not,the consolidation rate of the composite ground with SCCS columns is almost the same as that of the stone column improved-ground,and is much larger than that of the composite ground with the concrete piles.The consolidation rate of the ground improved by floating SCCS columns mainly depends on the penetration ratio of SCCS columns,the larger the penetration ratio,the higher the consolidation rate.While,the consolidation rate of the soft ground improved by fully penetrated SCCS columns mainly depends on the stiffness of core pile.When the core-column length ratio is higher,it increases with increasing the modulus of core pile.Other factors have negligible effects on the consolidation rate of these two types of composite ground.