Bearing Characteristics of Geosynthetic-Encased Recycled Concrete Aggregate Column Composite Foundation: A Numerical Evaluation

Abstract

To address the insufficient strength of conventional crushed stone in liquefiable and soft soil foundations, this research aims to fill the research gap regarding the bearing behavior of geosynthetic-encased recycled concrete aggregate column composite foundations, specifically in the context of group columns. This study proposes using recycled concrete aggregate (RCA) to form recycled concrete aggregate encased columns (RCAECs). Three-dimensional numerical models were developed in ABAQUS. Vertical loading analysis investigated the effects of column spacing, encasement stiffness, and encasement length on the bearing behavior of RCAEC composite foundations. Results show that increasing encasement length significantly enhances column bearing capacity when the column-top load exceeds 3 kN and the encasement length-to-column length ratio is between 20% and 94%, with optimum performance at 5~7 d. Encasement stiffness below 100 kN/m effectively improves both column and composite foundation capacity, beyond which the effect diminishes. Reduced column spacing enhances foundation reinforcement but lowers the column–soil stress ratio; an area replacement ratio of 10~20% is recommended. These findings provide theoretical support for RCAEC application in liquefiable and soft soil treatment.