Numerical Prediction of Stress-Deformation Behavior for a Bridge Approach Embankment on Soft Compressible Clay

摘要

The mechanically stabilized earth (MSE) approach embankments for a new state highway bridge across the Indian River were founded on 8-9 m of dense sand overlying a 20 m thick layer of soft, normally consolidated, high plasticity clay. Consolidation of the clay was accelerated through an array of prefabricated vertical (PV) drains. The instrumented 13.8m high fill was monitored during staged construction and for a period of 1.25 years after construction. The embankment settled more than 2 m, while large lateral spreading (～0.5 m) was restrained by overlying sand layers. The available site investigation data was carefully reinterpreted and a 2D finite element analyses was performed using rate-independent, effective stress models (Modified Cam-Clay and MIT-E3). The numerical predictions are generally in very good agreement with measured ground settlements and lateral deflections. This study highlights the importance of careful parameter selection in modeling the performance for soft ground construction in order to predict key features such as the asymmetric lateral spreading of the clay during consolidation.