Numerical study on load transfer effect of Stiffened Deep Mixed column-supported embankment over soft soil

Abstract

A new composite column technique referred to as Stiffened Deep Mixed (SDM) column has been adopted to support embankment over soft soil to mitigate the post-construction settlement, increase bearing capacity and enhance stability. The SDM column was formed by inserting a precast concrete core pile into the center of a Deep Mixed (DM) column immediately after the construction of DM column. Due to the complicate interaction between concrete core pile, DM column and surrounding soil, the load transfer mechanism between SDM column and surrounding soil has not been well understood yet. This paper presents a series of threeDimensional (3-D) finite-element analyses to investigate the load transfer effect of SDM column-reinforced ground under embankment. First, the numerical method was validated by a comparison with field data in terms of settlements and vertical stress on the head of SDM column. Then, based on the validated simulation method, the 3-D numerical model of the SDM column-supported embankment over soft soil was established, and the influence factors of length of DM column and concrete core pile, cross section area of concrete core pile, column spacing and embankment height on the load transfer effect were investigated, respectively. The results showed that the column spacing and height of embankment fill had significant effects on the load transfer between SDM column and surrounding soil, while the influences of length of DM column and concrete core pile, and cross section area of concrete core pile on the load transfer effect were minor. Finally, four current commonly-used design methods were assessed in the prediction of the efficacy of SDM-reinforced soil under embankment loading. The current commonly-used design methods showed great differences in the load transfer predictions of the SDM column-supported embankment over soft soil due to the existence of outer DM column socket. A modified method was proposed for the use of EBGEO (2011) in the design of SDM column-supported embankment over soft soil.

Lateral Thrust Distribution of Column-Supported Embankments for Limiting Cases of Lateral Spreading

“…They found the tension to be highest at the centerline and near zero at the shoulder and concluded that the results were affected by inadequate development length in the reinforcement. Research using numerical techniques has focused on the CSE vertical load distribution between columns and subsoil, but not on the lateral thrust distribution in the embankment, foundation, and geosynthetic reinforcement (Ariyarathne et al 2013a, b;Bhasi and Rajagopal 2013Borges and Marques 2011;Han and Gabr 2002;Huang andHan 2009, 2010;Jamsawang et al 2016;Jenck et al 2009;Liu et al 2007;Liu and Rowe 2016;Mahdavi et al 2016;Nunez et al 2013;Rowe and Liu 2015;Stewart et al 2004;Ye et al 2016;Yu et al 2016;Zheng et al 2009;Zhuang and Wang 2016). In this study, a numerical parametric study was used to analyze the lateral thrust distribution of CSEs for a wide range of conditions.…”

Analytical Solution for Consolidation Behaviors of Combined Composite Foundation Reinforced with Penetrated PCCSs and Floating DM Columns

“…The bearing performances of the PCCS were investigated by means of experimental, theoretical, and numerical analysis under vertical and lateral loads [26][27][28][29][30][31]. The inner core is installed to bear external loads, while the outer core can increase the shaft friction of the inner core and effectively transfer the inner core's axial force to the surrounding soil [18].…”

“…Based on tested results, Wang et al [33] found that the stiffened deep mixing (SDM) column-supported embankment could significantly reduce the postconstruction settlement by 27.3%-68.3 compared to the conventional DM column-reinforced composite foundation. Ye et al [26] established a series of finite element (FE) models to analyze the bearing mechanism of the SDM column-supported embankment.…”

Numerical Analysis of Bearing Behavior of the Prebored Precast Pile with an Enlarged Base

“…Numerical simulation is an effective tool for analyzing complex engineering problems, especially the pile-soil interaction. rough numerical analysis, Ye et al [7][8][9] discussed load transfer law and the effect of reinforced core on the performance and failure behavior of stiffened deep cement mixing piles. Based on the engineering application of PPEB pile technology in Zhejiang Province, China, Yang et al [10], Zhou et al [11], and Xie et al [12] used the numerical simulation method to analyze the influence of structure size of precast pile, soil properties, cement soil characteristics, and other factors on bearing capacity, which enriched the understanding of the characteristics of PPEB piles.…”