Behavior Of Stone Columns Research Articles

3D Finite Element Analysis of Stone Column Behaviour in Layered Soil with Geosynthetic Reinforced Soil Beds

3D Finite Element Analysis of Stone Column Behaviour in Layered Soil with Geosynthetic Reinforced Soil Beds

Consolidation Behaviour of Stone Columns Made with Tyre-Derived Aggregates

Consolidation Behaviour of Stone Columns Made with Tyre-Derived Aggregates

Experimental Studies on Ground Improvement Using Stone Column

This research examined the ground improvement technique for enhancing the load-bearing capacity and enhancing of weak or compressible soils. In this study, we focus on how we minimize the cost of ground improvement and make environment friendly solution for ground improvement. The research involves a review of the existing literature, including the Objectives, methodology, and case studies related to stone column implementation. Laboratory testing and field investigations are conducted to assess the geotechnical properties of the soil and the behavior of stone columns under different loading conditions. The project aims to provide insights into the geotechnical behavior of stone columns and their effectiveness in stabilizing weak soils. Furthermore, the study will explore the economic and environmental aspects of this ground improvement technique. The findings of this research are expected to contribute valuable knowledge to the field of geotechnical engineering, assisting engineers and construction professionals in making informed decisions regarding ground improvement methods. Keywords : Ground Improvement, Stone Column, Soil Sample, cost effective, environment friendly, Load Bearing Capacity, Black Cotton Soil, Soil Stabilization.

The Effect of Scrap Tires and Reclaimed Asphalt Pavement on the Behavior of Stone Columns

The objective of this investigation is to understand how to use waste tires to surround stone pillars and mix gravel with recycled asphalt pavement (RAP) and stone pillars to provide an environmentally friendly and cost-effective weak layer improvement method. To study the behavior of such stone columns, experiments were conducted in units consisting of a single stone column with recycled asphalt pavement as filling material and a single stone column covered with old tires. To test the effect of different mixing ratios, rapeseed content was selected from 0% to 100%. Elasticity tests were conducted on cladded and nonclad stone column samples. Furthermore, direct shear tests were conducted on samples with different ratios of gravel and rapeseed mixtures. The results of the load-bearing capacity test show that the cover of the stone columns with old tires can significantly increase the load-bearing capacity. Replacing 25% of natural stone column aggregates with RAP increases the load capacity. But as the percentage of RAP in the mixture increases from 25% to 100%, the loading capacity decreases. Another advantage is the reinforced stone column. From the point of view of ecology, an advantage is the use of recyclable materials.

Investigating stone column effectiveness for sabkha soil improvement: field tests and numerical model

This study explores the application of stone columns to improve the bearing capacity of sabkha soil for the construction of a Lattice Communication Tower foundation in the Eastern Province of Saudi Arabia. Geotechnical investigation report, an on-site footing loading test to evaluate the foundation's bearing capacity and settlement behavior following stone column installation, and post-cone penetration tests (CPT) to assess soil densification are all part of the study data. The uppermost 4 m of the soil profile comprise a medium to dense layer of sand with silt, followed by a 12-m layer of weak sabkha soil (SPT, N less than 4). Below the sabkha layer, the strata exhibit varying densities, ranging from medium to dense and very dense layers, extending to the maximum depth of investigation. The comparison of Pre- and Post-CPT data revealed significant improvements in the sand and silt layer above the sabkha layer, as well as moderate improvements in the upper portion of the sabkha layer. However, the majority of the sabkha soils and underlying soil layers did not show significant improvement. Plaxis 3D numerical models were employed to provide insights into the performance of the composite area encompassing stone columns and the surrounding soil. Comparing field tests and numerical models showed that neglecting stone column installation effects in numerical models led to overestimating settlements. However, when examining the field data and numerical results with a raised coefficient of lateral earth pressure when of K∘=2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${K}_{^\\circ }=2$$\\end{document}, a distinct alignment between settlement values consistent with those derived from field testing. The findings highlight the importance of including site-specific conditions and installation effects in numerical modeling to accurately predict the behavior of stone columns in sabkha soils.

Improvement of consolidation settlement beneath square footings using uncased and encased stone columns

Stone columns are considered a sustainable stabilization technique that has environmental compatibility and economic aspects to enhance the properties of soft soils below the overlying structures. This paper explores the effects of main related parameters on the consolidation settlement of square footing that rests over soft clay soil that treated using encased and unreinforced (uncased) stone columns. A Finite element modeling is established using PLAXIS 3D Software and was verified by previous experimental data. An extensive parametric study is performed numerically using various stone column parameters such as different replacement area ratios (Ar), numbers, lengths, properties, and geotextile lengths to determine the strain–stress behavior of stone columns. The developed finite element models found that the stone column area ratio (Ar) reduces both the settlements beneath the foundation and excess pore water pressure by 43% and 41%, respectively at Ar = 20%. Also, by increasing the penetrated depth and elastic modulus of stone columns, the settlement decreases significantly under footing. Conversely, there are slight effects of the stone columns number that have a constant area ratio on the foundation settlement. Furthermore, the optimal geotextile encasement length that reduces the settlement effectively was achieved when the encasement height ratio was half of the stone column height. Utilizing half-height encasement leads to cost savings, as it yields a 34% reduction in settlement from the uncased case while the settlement reduction achieved with full-height encasement was 44%.

Study of the Effect of Installation of Stone Columns on the Stability of Soil Slopes using Finite Element Method

There are several ways to mitigate the failure of a soil slope. The installation of stone columns for this purpose, is easy as well as economical. As their strength is greater than that of soil, they disrupt the slip surfaces. Also being more porous, they dissipate the pore pressure generated in the soil in the vicinity of the stone columns to a certain extent. This paper illustrates 2D finite element analyses carried out to simulate the behavior of stone columns in cohesive soil using the computer program PLAXIS. Parametric study was conducted to analyze the effect of number, length and diameter of the stone columns on the Factor of Safety of the soil slope. The F.O.S. of the soil slope was predicted using prediction models created using artificial neural networks (ANN) considering slope geometry like slope angle and height, material properties like cohesion and angle and internal friction of soil as well as granular material used in the columns, and the stone column parameters like the stone column’s number, length, diameter and the centre to centre (c/c) distance between two adjacent columns as input parameters. It was found that introduction of stone columns significantly improved the stability of the soil slopes. Further, it was seen that all the parameters considered in the study influenced the Factor of Safety of the soil slope.

Investigation on Behavior of Stone Columns in Soils under Predominant Settlement

Abstract: Recent advances have made stone columns more efficient and effective for addressing soil instability and improving the load-bearing capacity of weak soils. The present study aims to show that the behavior of stone columns can support most of the load transferred to the soil. The use of innovative materials, such as recycled glass, plastic, or tire shreds, as a replacement for traditional stone fill, has been investigated in recent years and has shown promising results in cost and sustainability. The development of advanced numerical modeling techniques, such as finite element analysis, has enabled engineers to understand the behavior of stone columns better and optimize their design for specific soil conditions. The load-displacement characteristics are considered governing parameters for understanding the capacity of stone columns. The study reveals that, stone column method significantly increases strength with the use of concrete waste lo demolished waste rather than stone aggregate, which can overcome this soil behavior. Additionally, stone columns are helpful for soil stabilization in areas with high water tables when other stabilization techniques are ineffective

Experimental and numerical study of the settlement behavior of soil reinforced by stone columns

Purpose The paper aims to present an experimental and numerical investigation of the load–settlement behavior of soil reinforced by stone column, as well as to evaluate the plane strain unit cell model for the analysis of stone columns. Design/methodology/approach The numerical analysis was done using both axisymmetric and plane strain models. The elastic perfectly plastic behavior of Mohr–Coulomb was adopted for both soil and column material. The numerical results of this study were validated by the comparison with the in-situ measurements of a full-scale loading test on a stone column. This study also evaluated the effect of different parameters involved in the design of a stone column, including Young’s modulus of the column material, column diameter, spacing between the stone columns and Poisson’s ratio of the column material. Findings After the numerical simulation, the results from both axisymmetric and plane strain models are quite comparable. In addition, the numerical results revealed that the stone column with low spacing, a large diameter and a high Young’s modulus indicated better behavior against the settlement. Originality/value The axisymmetric unit cell model was used in many numerical studies on the behavior of stone columns. In the present work, a field load test on stone column was simulated using a plane strain unit cell model. This research adds that the plane strain unit cell model can be used to predict the settlement of reinforced soil with stone columns.

Behaviour of stone columns based on 24 factorial experiments with uniformly graded materials

Behaviour of stone columns based on 24 factorial experiments with uniformly graded materials

Numerical Plane-Strain Modelling of Stone Columns: Installation Process, Single and Group Column Behaviour

The scope of this paper is to emphasize the critical issues related to the axisymmetric and plane-strain modelling of single and group of stone columns constructed to stabilise soft soils. A simple technique based on the expansion of the column shaft was used to simulate the column installation so that the excess pore pressures during this process were calculated for a single column under axisymmetric conditions. Classical cavity expansion theory was also used for the same purpose. The group behaviour of stone columns was discussed by two-dimensional plane—strain numerical models. Plane-strain modelling of stone columns should consider the conversion of stiffness and the drainage properties of the columns and the soft soils to the plane-strain conditions. The validity of two different conversion methods based on the equivalent plane-strain stiffness and equivalent plane-strain permeability coupled with the expansion of the column shaft technique were investigated. An existing well-documented centrifuge test data were used as a reference for numerical models of axisymmetric single column and plane-strain column groups. The measured and calculated results were in good agreement for the case where the finite element model was constituted based on the equivalent plane-strain permeability. The results of this study intend to bring insight to the plane-strain modelling of a group of stone columns.

Numerical Analysis of the Settlement Behavior of Soft Soil Improved with Stone Columns

The use of column-like elements for improving both the settlement performance and bearing capacity of foundations constructed over soft soils is well understood for large groups of columns supporting an infinitely wide load, such as embankments and slabs. However, little is still understood for lightly loaded, low-rise structures supported by pad foundations constructed on a finite number of stone columns, particularly when a crust layer is present at the top of the soft soil. In this study, a comprehensive 3D finite element analysis is used to investigate the influence of key design parameters, such as column spacing, column length, footing shape, and the presence of a crust layer, on the settlement behavior of stone columns to support shallow foundations. The results show that the modeling of a well-characterized soft soil profile predicts well the long-term settlement using both drained and undrained analyses. It was found that the presence of a stiff crust layer has a significant influence on the deformational mode of the stone columns which is not captured by laboratory modeling.

Behaviour of Model Stone Column Subjected to Cyclic Loading

Behaviour of saturated soft clay deposits subjected to cyclic stresses is of considerable importance in the design of railway infrastructure, since these deposits are characterised by very low bearing capacity and excessive settlement. Stone column is a well-established method that used to improve both bearing capacity and reduce settlement of such soil. However, much of the work to date has dealt with the behaviour of stone columns under static loading. Little is known about their response to cyclic loading. A laboratory based study was undertaken to investigate the response of both column and the surrounding soft soil to cyclic loading using a series of static and cyclic loading triaxial tests under undrained condition. Testing was performed on normally consolidated specimens of soft clay (undrained shear strength of ≈ 12 kPa, diameter 100 mm, and 200 mm height) reinforced with 28 mm diameter stone columns. Effects of loading frequencies at range of cyclic stress ratios were examined. It was found that the cumulative strain developed was dependent on the cyclic stress ratio, but independent of frequency from 0.5 to 3 Hz.Overall, stone columns have shown the potential to strength subgrade when exposed to cyclic loading, and hence reduce both capital costs (reduce the ballast needed for subbase), and operational cost through extended maintenance period.

Laboratory Model Tests on Stone Column and Pervious Concrete Columns: A Comparative Study

This study aims to perform laboratory model tests to investigate the load-deformation behavior of stone columns (SCs), pervious concrete columns (PCCs), and composite columns (CCs). Here, CC refers to the column which has the upper portion made of PCC and the lower portion made of SC. The parameters investigated in this study include column diameters, column lengths, and installation methods (pre-cast and cast-in-situ methods). The results of the model tests reveal that the axial load-carrying capacity of PCC is nearly 8 times more than that of SC with the same diameter. Moreover, it is also observed that at the top portion of SC, with the PCC length which is about 3.75 to 5 times the column diameter, the load-carrying capacity can significantly increase. It is concluded that the installation methods have marginal influence on the load-deformation behavior of PCC.

Assessment the Behavior of Stone Columns under Confined Compression

The emphasis of current work is on assessing the settlement improvement ratio, which is described as the ratio between the settled soils treated with a stone column and the settlement of the non-treated soil (Sr = Streated/Suntreated). The research was conducted using a 300 mm diameter and 300 mm high stone-column container testing model. On 14 modeled stone columns made only from crush stones and using various backfill content, model tests including static axial compression tests were performed. The substance used in the stone backfill column had been changed by sand or lime or cement percentages. The shear strength prepared by the containers varied between 5.5 kPa and 13.5 kPa. Results show that the settlement ratio values, Sr achieved with crush stone, crushed stone +50% sand, crushed stone +5% dry lime, crushed stones +10% dry lime, crushed stone +2.5% cement +5.0% crushed stone +5.0% cement, respectively, was 0.23, 0.12, 0.16, 0.15 and 0.09. In other words, there is a drop in the settlement from 77% to 91%.

A Review on the Behaviour of Combined Stone Columns and Pile Foundations in Soft Soils when Placed under Rigid Raft Foundation

In the last few decades, it has been observed that raft foundations are very commonly used as a foundation solution for moderate to high rise structures either by resting on stone columns or on piles in soft soils. It is believed that, combining stone columns and piles in one foundation system is the more suitable foundation for medium rise structures. The combined foundation system provides a superior and more economical alternative to pile, and a more attractive alternative to stone columns in respect to ground improvement. This paper presents the review of existing studies reported in the literature in the last two decades about the behaviour of stone columns under raft foundations and piled raft foundation in soft soil, notably the failure mechanism and the bearing capacity. Also, a limited work from the literature concerning the performance of combined (pile/stone columns) foundation system in soft soil is comprised. Furthermore, very extensive ongoing research work regarding the investigation and study on the performance of combined (pile/stone columns) foundation system in soft soils is discussed. The main goals and methodology to study the performance of the combined (pile/stone columns) foundation systems in soft soil are also addressed.

Utilization of stone column for improving seismic response of foundation on soft clay- Numerical study

Nowadays, some projects have to be constructed in areas having thick layers of soft clay. These soft soils with low shear strength and high voids ratio, lead to excessive settlements even if subjected to low vertical or lateral loads. For this reason, soft clays are considered problematic soils for foundation purposes. Several improvement techniques have been done to enhance such clay. Stone columns have been used to improve soft soils by increasing it carrying capacity and reducing the settlement. In this paper, a numerical study on seismic behavior of stone column in soft clay subjected to earthquake loading has been performed. A two-dimensional plane strain program PLAXIS (dynamic version) is used for the present numerical modeling. A series of modeled stone columns were simulated with different diameters and spacing between columns. Also, the influence of geotextile encasement on the performance of stone columns, foundation systems in soft clay is investigated and compared with the behavior of ordinary stone columns without casing. The results showed that the ordinary stone column with small spacing and larger diameter has a greater bearing capacity and give a smaller settlement, compared to the column with large spacing. In addition, the geotextile encasement for stone column can be provided a significant increase in stone column capacity as well as a huge reduction in settlement is considered with increasing the encasement strength.

Seismic Analysis of Floating Stone Columns in Soft Clayey Soil

The response of floating stone columns of different lengths to diameter ratio (L/D = 0, 2, 4, 6, 8, and 10) ratios exposed to earthquake excitations is well modeled in this paper. Such stone column behavior is essential in the case of lateral displacement under an earthquake through the soft clay soil. ABAQUS software was used to simulate the behavior of stone columns in soft clayey soil using an axisymmetric finite element model. The behavior of stone column material has been modeled with a Drucker-Prager model. The soft soil material was modeled by the Mohr-Coulomb failure criterion assuming an elastic-perfectly plastic behavior. The floating stone columns were subjected to the El Centro earthquake, which had a magnitude of 7.1 and a peak ground acceleration of 3.50 m/s2. The surface displacement, velocity, and acceleration in soft clayey enhanced by floating stone columns are also smaller than in natural soft clay. The findings of this research revealed that under the influence of earthquake waves, lateral displacement varies with stone columns of various lengths.

Small scale behavior of stone columns encased by tires

Stone columns are one of the best-suited methods of ground improvement for sites consisting of soft clays, silts and silty sands. Stone columns need to be supported against bulging failure as the main reason that reduces their bearing capacity. Disposal of scrap tires is one of the principal environmental problems around the world. Therefore, the reuse of scrap tires has grown globally. This paper investigates the behavior of stone columns encased by scrap tires which has the potential of replacing other encasements. Stone columns with diameters of 66, 80 and 92 mm which are one-tenth of original tire sizes have been tested in a large box, and the load-carrying characteristics of them are analyzed. Based on the results, by increasing the diameter of the encasement stone column, the benefit of the encasement increases. In addition, tests on the groups of stone columns with a diameter of 66 mm were carried out to investigate the presence effects of neighboring columns on the reference load. Furthermore, a comparison has been made with the results of ordinary stone columns and encased stone columns with geotextile to obtain the benefits of scrap tire columns. The bearing capacity of both single and group of stone columns encased with the scrap tire increases more than the ordinary stone columns. However, the bearing capacity of geotextile encased stone column is more than the other groups. Further, numerical analysis has been conducted to implement full-scale reinforced columns. The results illustrate that using scrap tires reduces bulging failure and increases the bearing capacity of stone columns. Accordingly, scrap tires replace the geotextile (as usual encasement) because their amount of bearing capacities are similar to each other especially in columns with larger diameters.

Three Dimensional Numerical Study on Behavior of Geosynthetic Encased Stone Column Placed in Soft Soil

Ordinary stone column (OSC) reinforced soft soils undergo excessive settlements under vertical stresses due to the lack of adequate lateral support from the surrounding native soil. To overcome this issue, stone columns are suitably encased by a geosynthetic material having high axial stiffness, which provides the required additional confinement. A numerical analysis aimed at analyzing the effect of geosynthetic encasement on the load settlement behavior of geosynthetic encased stone columns (GESC) under vertical stresses is presented. Three dimensional (3D) models were developed in PLAXIS3D to simulate the behavior of stone column reinforced soft soils using the unit cell idealization concept. The numerical models were first validated with the help of experimental data of model tests on GESCs from literature. Various parameters were varied to quantify their impact on the load settlement behavior under column only loaded condition. The parameters varied include the diameter of GESCs, spacing to diameter (S/D) ratio, pattern of stone column installation, geosynthetic encasement stiffness, length of encasement, length of floating column, cohesion of soil and friction angle of stone column infill. Increase in the diameter of GESCs led to increased settlement for a particular vertical load intensity. The bearing capacity improved with increase in the geosynthetic stiffness, encasement length, length of floating GESCs, the cohesion of soil and the friction angle of the stone column infill. Increase in S/D ratio decreased the bearing capacity and triangular pattern of stone column installation was found to be more efficient. Moreover, the lateral bulging indicated a reducing trend upon increasing the axial stiffness of encasement.