软土地基高速公路扩建中新老路堤相互作用数值分析

Numerical Analysis of Interaction Between Old and New Embankment in Widening of Freeway on Soft Ground

采用弹塑性有限元方法分析了老路边坡开挖和加宽部分路堤填筑对老路变形特性的影响。计算结果表明:原有路堤边坡削坡和台阶开挖将会使得老路中心的竖向沉降略有增加,坡脚侧向位移回缩,且不同开挖方式对原有路堤影响不同;加宽部分路堤的填筑将会使得老路中心上抬,路肩点发生较大附加沉降,引起老路路肩与路中心之间产生过大的附加差异沉降,明显加大路面横坡,极易导致对老路路堤、路面的拉裂,降低道路等级,必须采用合适的软基处理方案对加宽部分软基进行处理。另外,宽路堤的变形特性不同于窄路堤,其沉降呈中央小两边大的形式,并且最大沉降位置随路堤高度的增加向路堤中央移动,了解宽路堤变形的这一特性有助于其软基处理方案以及加固效果监测方案的优化。

The elastic-plastic finite element method was employed to analyze the influence of old freeway slope excavation and part widening embankment filling on old road deformation characteristics. The results indicate that slope cutting and stepping excavation of old embankment induce the increase of vertical settlement in the center of old freeway and the decrease of lateral deformation at the foot of slope respectively, and that the construction of new embankment leads to differential settlement between the center and the shoulder of old embankment, which is response for the pavement cracking. Appropriate ground improvement techniques should be employed to reduce the effect of the widening on the old embankment. In addition, the behavior of ground under broad embankment is different from that under narrow embankment. The settlement on two sides of embankment is more than that at the middle part, and the location of the maximum settlement moves toward to the middle part as the increase of embankment height, and knowing the characteristics will help to optimize soft ground improvement techniques and reinforced monitoring techniques.