Improvement of Soft Soil Using Linear Distributed Floating Stone Columns under Foundation Subjected to Static and Cyclic Loading

Abstract

A stone column is one of the soil improvement methods that are mainly used for improving the geotechnical behavior of soft soils. For deep improvement of soft soil, the floating stone columns are considered the best and effective economically which provide lateral confinement and drainage and longitudinal skin friction. In this study, six tests were carried out on the natural soft soil of undrained shear strength of 5.5 kPa improved by single and two linear distributed floating stone columns. The stone column dimensions are 30 mm in diameter and 180 mm in length and the stone column material is sand of high internal friction angle of 48°. The natural and improved soil samples are tested under isolated raft foundation of dimensions 120×120 mm subjected to vertical static and cyclic loading of frequency 2Hz and continued for 50 seconds. The results showed a significant improvement in soil bearing capacity when reinforced with stone columns despite the small area replacement ratio, where the bearing capacity of improved soil increased by 120 to 145%. The compressibility of improved soil decreased by 57 to 86% in comparison with that of natural soft soil. Also, the floating stone columns reduced the porewater pressure, where the stone columns considered efficient in providing short drainage pathways. This can be one of the reasons why soil reinforced with floating stone columns hold higher cyclic and static stresses regardless the end bearing of stone columns.

Settlement Analysis of a Sandy Clay Soil Reinforced with Stone Columns

“…Stone columns cannot be installed in fine-grained soils as in some soils, and their effect can be counterproductive regardless of their diameter, spacing, and height. Loose sandy soils (including silty or clayey sands) are a potential type of soil in which stone columns can be installed without extra lateral support, but stone column installation in sensitive clays and silts is limited [12,18,44]. The characteristics of the soil investigated in this study (having a sensitivity value <4) are such that a beneficial effect from the installation of stone columns could be evaluated.…”

“…Various researchers [11][12][13] demonstrated the effectiveness and efficiency of using stone columns for soil stabilization, as this method can improve the strength properties and reduce consolidation settlements in soft soils. It also provides a much more cost-effective and sustainable alternative than piling and deep foundation solutions.…”

Seismic Analysis of Floating Stone Columns in Soft Clayey Soil

“…A single stone column was nominated from an experimental study on floating stone column behavior under different types of loading that have been studied in reference [12]. The description of the studied model cases is described in the following sections.…”

“…Seismic numerical modeling of a single stone column of 0.03 m diameter with different L/D ratios has been studied. This model was investigated by reference [12] as a single stone column in soft clay soil and subjected to the El Centro earthquake's ground acceleration.…”

Numerical Modeling of Encased Stone Columns Supporting Embankments on Sabkha Soil

“…Nowadays, structures such as dams, road embankments and storage tanks, frequently have many problems with irregular, excessive settlements or overall stability due to geological situation and weak soil. Stone columns (likewise known as granular piles) are increasingly used as soft soil reinforcement to support a variety of structures [1], in other words, these are soft soil improvement techniques which are commonly and successfully used to reduce settlement, reduce the liquefaction potential, and to speed up the consolidation of soft soils [2][3][4]. When the stone columns (OSCs) are installed in extremely soft soils (cu < 15 kPa) such as peat soils, and marine clays, etc., the lateral confinement presented by the surrounding soil may not be sufficient to form the stone column.…”