Bearing Characteristics of Composite Foundation Reinforced by Geosynthetic-Encased Stone Column: Field Tests and Numerical Analyses

Abstract

In order to study the bearing characteristic of the geosynthetic-encased stone column (GESC) on the composite foundation, a series of field tests and numerical simulation were carried out on the composite foundations reinforced by the traditional stone column and the GESC. The pile–soil stress ratio, excess pore water pressure and lateral displacement of two kinds of composite foundations were monitored. The effects of geotextile stiffness, geotextile wrapping length and gravel internal friction angle on the composite foundation with the GESC were analyzed by establishing different numerical models. The results show that the GESC can bear larger loading compared with the traditional stone column. The pile–soil stress ratio of the composite foundation with the traditional stone column gradually increases from 1.1 to 1.5 with the increasing of the embankment height. However, the pile–soil stress ratio of the composite foundation with the GESC reaches 1.5 at the initial filling stage and increases to 1.7 with the filling construction. The drainage effect of the GESC is better than that of the traditional stone column, and the GESC can effectively improve the overall stiffness of stone column, so as to reduce the lateral displacement of soil mass. The increases of geotextile stiffness, geotextile wrapping length and gravel internal friction angle can improve the bearing performance of the composite foundation with the GESC. However, after geotextile stiffness and wrapping length reach a certain value, the influence of its lifting amount on the composite foundation will be reduced.