Behaviour of soft ground improved by conventional and geogrid-encased stone columns, based on FEM study

Abstract

Construction of embankments on soft natural soil may be a challenge, owing to its low shear strength and high compressibility. Stone columns, which depend on lateral support from the soft ground, have been utilised to accelerate foundation consolidation, and to increase foundation bearing capacity. To keep the drainage function, and to improve the stone columns as reinforcing elements, geosynthetics are used for column encasement. In this research, the behaviour of full-scale unreinforced and reinforced Bremerhaven clay with conventional and geogrid-encased stone columns under embankment loads is analysed numerically. The consolidation analysis is applied to investigate the long-term behaviour of the clay. The results show that the stone columns in the Bremerhaven clay increase the bearing capacity and accelerate the reduction of excess pore water pressure of the foundation. Once the stone columns are encased, more improvement occurs in their performance in soft soil. The analyses also indicate that stress concentration generation in the stone columns contributes significantly to the acceleration of soil consolidation.

Behavior of Geosynthetic-Encased Stone Columns in Soft Clay: Numerical and Analytical Evaluations

“…Since most of the analytical solutions have considered unit cell idealization in their procedure, this concept and axisymmetric analyses have been adopted to assess the influence of geosynthetic encasement on the behavior of stone columns (EBGEO, 2011;Elsawy, 2013;Almeida et al, 2013;Hosseinpour et al, 2014;Alkhorshid, 2017).…”

Settlement behavior of embankment on geosynthetic-encased stone column installed soft ground – A numerical investigation

“…The concept of encasing granular columns with geosynthetics to increase their capacity has been acknowledged by numerous researchers (Raithel and Kempfert, 2000;Kempfert et al, 2002;Raithel et al, 2002;Alexiew et al, 2005;Brokemper et al, 2006;Murugesan and Rajagopal, 2006, 2007, 2010Lee et al, 2007;Yoo et al, 2007;Gniel and Bouazza, 2009;Hong, 2009, 2014;Yoo and Kim, 2009;Yoo, 2010;Yoo and Lee, 2012;Zhang et al, 2012;Almeida et al, 2013;Dash and Bora, 2013;Elsawy, 2013;Maheshwari and Chauhan, 2013;McCabe et al, 2013;Shahu, and Reddy, 2014;Ali et al, 2014). In addition to its ground improvement effect in terms of load carrying capacity, Tang et al (2013) has demonstrated the effectiveness of geosynthetic encased stone columns for ground improvement of liquefaction mitigation.…”

Column Supported Embankments with Geosynthetic Encased Columns: Validity of the Unit Cell Concept

“…The concept of a "unit cell" has been the most popular approach for numerically simulating the response of CSEs when GECs are used as the deep foundation elements (e.g., Murugesan and Rajagopal 2006;Malarvizhi and Ilamparuthi 2007;Park et al 2007;Almeida et al 2013;Elsawy 2013). Yoo and Kim (2009) compared the results of axisymmetric, 3-d unit cell, and fully 3-d models of CSEs with GECs, but without geosynthetic reinforcement placed over the columns.…”