Numerical Analyses of the Optimum Length for Stone Column Reinforced Foundation
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(2020) 6:34
ORIGINAL PAPER
Numerical Analyses of the Optimum Length for Stone Column Reinforced Foundation Abdeldjalil Remadna1 · Sadok Benmebarek1 · Naima Benmebarek1 Received: 4 February 2020 / Accepted: 10 July 2020 © Springer Nature Switzerland AG 2020
Abstract The paper presents 3D numerical simulations that investigate the settlement performance for small groups of stone columns under a rigid circular footing. Particular consideration is given to the effects of stone column installation and load level on the optimum length of the stone columns. The results show that taking into account the installation effect by increasing the lateral earth pressure coefficient of the soil reduces the deformation of the columns and the surrounding soil. This leads not only to a reduction in the settlement of the footing but also to a reduction in the optimum length of the stone columns. This optimum length of columns is not constant, it increases with the increase in the load applied to the footing. However, overestimating the installation effect has a negligible consequence on the footing settlement and the optimum length of columns. In addition, the study shows that, for loads exceeding the working load levels of unreinforced soil, the optimum length of the columns is controlled by the extent of the total shear strains beneath the footing evolving with the applied load. Keywords Numerical modeling · Stone column · Installation effect · Optimum length · Settlement · Footing
Introduction Ground improvement using stone columns is a popular technique for enhancing soft soils. This technique consists of incorporating a granular material into soft soil, usually ballast, to obtain a composite soil with better characteristics than untreated soft soil. This operation improves bearing capacity, reduces settlement, accelerates drainage and reduces the soil’s liquefaction potential. Stone columns are generally installed as an infinite grid of columns for the improvement of large areas, such as wide rafts and embankments. The deformation mechanism of the columns in this case is almost identical, and the settlement performance can only be studied using the well-known unit cell model, i.e. only one column and the corresponding * Abdeldjalil Remadna [email protected] Sadok Benmebarek s.benmebarek@univ‑biskra.dz Naima Benmebarek n.benmebarek@univ‑biskra.dz 1
NMISSI Laboratory, Department of Civil Engineering and Hydraulic, Biskra University, BP 145, 07000 Biskra, Algeria
surrounding soil [1–5]. Recently, small groups of stone columns have been used to improve small areas, such as isolated or strip footings. The ability of stone columns to improve footing performance has been demonstrated by several field measurements [6–8]. However, the deformation mechanism of small groups of columns under a rough rigid footing is very different from that of an infinite grid of stone columns. Muir Wood et al. [9] indicated that columns located at a different location under the footing do not have the same deformation and therefore an analys
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