Behavior and Numerical Evaluation of Cement-Fly Ash-Gravel Pile-Supported Embankments over Completely Decomposed Granite Soils

Abstract

This study presents a full-scale test of high-speed railway embankments to investigate the performance of cement-fly ash-gravel (CFG) pile-supported embankments over completely decomposed granite (CDG) soil foundations. To compare the applicability of different numerical models to the performance of CFG pile-supported embankments over CDG soils, a numerical study was conducted to analyze the embankments in terms of settlements, horizontal displacements, and load transfer from soils to piles using the finite-element software PLAXIS 2D. Furthermore, the numerical results were verified by the field measured results. First, the effectiveness of use of an equivalent area (EA) method, interface elements, and constitutive models is studied. The results show that the CFG pile-supported embankments modeled by the EA method combining with interface elements is adaptive to analyze the behavior of the improved embankments. In this case, the modified Cam-clay (MCC) model yields much better results than the Mohr-Coulomb (MC) model. Afterward, parametric analysis was conducted to study the influences of pile length and area replacement ratio on the deformability of CFG pile-supported embankment. The influences of these factors are compared and rated in terms of their degree of importance.