Performance of Reinforced Soft Soil Using Geogrid-Encased Granular Piles Under an Embankment

Geosynthetic encasements are used to promote the water outlet and reinforcement efficiency of stone piles in weak soil. The current study focuses on simulating an embankment with field measurements built on soft soil improved by conventional stone piles (CSPs). Both 3D and 2D plane strain models were employed to model various embankment components. The granular piles were improved with geosynthetic materials to evaluate the encasement leverage on the stone piles performance in soft soil. Consolidation process was conducted to examine the reinforced clay behavior at long-term conditions. The finite element analyses findings indicated good matching with field measurements for soft soil reinforced with CSPs. The 3D models demonstrated better alignment with field data compared to the 2D model. The study also investigated the impact of embankment height increment on improved soil using CSPs and encased stone piles (ESPs) through both 3D and 2D simulations. Soft soil reinforced with ESPs showed improved performance, including reduced settlement and pile bulging, and shorter consolidation times compared to the reinforcement with CSPs. The settlement reduction became more significant as consolidation progressed. The water pores pressure in the improved clay with ESPs dissipated faster than that in the improved clay with CSPs. Additionally, ESPs induced greater effective stress and stress concentricity than those in CSPs. The encasement also reduced the total stress in the clayey soil between piles, which contributed to faster consolidation. Furthermore, ESPs effectively reduced lateral spreading of the embankment, ensuring greater safety for adjacent structures.