• Geomechanics and Engineering
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• v.29 no.6
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• pp.645-655
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• 2022

Granular columns have recently found widespread use in underground construction. The behaviour of granular columns under vertical loads has been extensively studied, specifically in relation to vertical load capacity obtained by bulging of the column body, including the behaviour after encasement of material. Determining the shear strength of loose soils reinforced with granular columns has received less attention. After the observations of lateral deformation near the toe of the embankment, attempts have been made to strengthen the lateral strength of granular columns. The purpose of this research is to look into the effects of different encasement conditions on the lateral load capacity of granular columns. This was accomplished by three-dimensional finite element analysis with FEM software. Various normal pressures and two different encasement configurations, namely single layer encasement and double layer encasement, with differing tensile strengths, were used in this study to determine their effect on lateral resistance. The failure envelope for a single column planted in loose sand was used to analyse the findings for three different granular column diameters, as well as the impact of different encasement conditions. According to the findings, the inclusion of a Granular Column enhanced the shear strength and overall stiffness of the loose sand bed, and the encasement of the Granular Column helped in deriving higher lateral resistance.

• Geomechanics and Engineering
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• v.10 no.5
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• pp.617-633
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• 2016

A numerical study has been conducted to examine the improvement achieved in the ultimate pullout capacity of horizontal circular anchor plates embedded in undrained clay, by constructing granular columns of varying diameter over the anchor plates. The analysis has been carried out by using lower bound theorem of limit analysis and finite elements in combination with linear programming. The improvement in uplifting capacity of anchor plate is expressed in terms of an efficiency factor (${\xi}$). The efficiency factor (${\xi}$) has been defined as the ratio of ultimate vertical pullout capacity of anchor plate having diameter D embedded in soft clay reinforced by granular column to the vertical pullout capacity of the anchor plate with same diameter D embedded in soft clay only. The variation of efficiency factor (${\xi}$) for different embedment ratios and different diameter of granular column has been studied considering a wide range of softness of clay and different value of soil internal friction angle (${\phi}$) of the granular material. It is observed that ${\xi}$ increases with an increase in diameter of the granular column ($D_t$) and increase in friction angle of granular material. Also, the effectiveness of the usage of granular column increases with decrease in cohesion of the clay.

• Journal of Korean Society of Water and Wastewater
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• v.31 no.6
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• pp.577-586
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• 2017

One of the major sources causing eutrophication and algal blooms of lakes or streams is phosphorus which comes from point and nonpoint pollution sources. HAP (hydroxyapatite) crystallization using granular alkaline materials can achieve the decrease of phosphorus load from wastewater treatment plants and nonpoint pollution control facilities. In order to induce HAP crystal formation, continuous supply of calcium and hydroxyl ions is required. In this research, considering HAP crystallization, several types of lime-based granular alkaline materials were prepared, and the elution characteristics of calcium and hydroxyl ions of each were analyzed. Also, column tests were performed to verify phosphorus removal efficiencies of granular alkaline materials. Material_1 (gypsum+cement mixed material) achieved the highest pH values in the column tests consistently, also, Material_2 (gypsum+slag mixed material) and Material_3 (calcined limestone material) achieved over pH 9.0 for 240 hours (10 days) and proved the efficiencies of long-term ion supplier for HAP crystallization. In the column tests using Material_3, considerable pH increase and phosphorus removal were carried out according to each linear velocity and filtration depth. T-P removal efficiencies were 87.0, 84.0, 68.0% and those of PO4-P 100.0, 97.0, 80.0% for linear velocity of 1.0, 2.5, 5.0 m/hr respectively. Based on the column test results, the applicability of phosphorus removal processes for small-scale wastewater treatment plants and nonpoint pollution control facilities was found out.

• Journal of Environmental Science International
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• v.7 no.6
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• pp.773-782
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• 1998

The adsorption experiment of phenol(Ph) from aqueous solution on granular activated carbon was studied in order to design the fixed-bed adsorption column. The experimental data were analyzed by unsteady-state, one-dimensional heterogeneous model. Finite element method(FEM) was applied to analyze the sensitivity of parameter and to predict the fixed-bed adsorption column performance on operation variable changes. The prediction model showed similar effect to mass transfer and intraparticle diffusion coefficient changes suggesting that both parameter present mass transfer rate limits for GAC-phenol system. The Freundlich constants had a greater effect than kinetic parameters for the performance of fixed-bed adsorption column. FEM solution facilitated prediction of concentration history in solution and within adsorbent particle.

• Journal of the Korean GEO-environmental Society
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• v.7 no.1
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• pp.5-18
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• 2006

Stone column or granular compaction pile have been used in widely during the several decades as a technique to reinforce soft cohesive soils and increase bearing capacity, accelerate consolidation settlement of the foundation soil. The bearing capacity of the granular compaction pile is governed mainly by the lateral confining pressure mobilized in the native soft soil to restrain bulging collapse of the granular pile. Therefore, the technique becomes unfeasible in soft, compressible clayey soils that do not provide sufficient lateral confinement. This paper presents the main results of numerical study of granular compaction pile which is partly mixed with lean concrete. 3D finite element analyses are performed with composite reinforced foundations by both granular compaction pile and partly mixed granular compaction pile with lean-mixed concrete. Finally, a regression formula for calculating settlement reduction coefficients is proposed in this study by using numerical analysis results and applicability of the proposed method is identified by a series of parametric study about settlement reduction coefficients.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2005.10a
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• pp.336-342
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• 2005

Stone column or granular compaction pile have been used in widely during the several decades as a technique to reinforce soft cohesive soils and increase bearing capacity, accelerate consolidation settlement of the foundation soil. The bearing capacity of the granular compaction pile is governed mainly by the lateral confining pressure mobilized in the native soft soil to restrain bulging collapse of the granular pile. Therefore, the technique becomes unfeasible in soft, compressible clayey soils that do not provide sufficient lateral confinement. This paper presents the main results of numerical study of granular compaction pile which is partly mixed with lean concrete. 3D finite element analyses are performed with composite reinforced foundations by both granular compaction pile and partly mixed granular compaction pile with lean-mixed concrete.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.1415-1426
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• 2008

Stone columns, locally called "GCP (granular compaction pile)" can be used to improve strength and resistance against lateral movement of a foundation soil like rigid piles and piers. Also installation of such a discrete column facilitates drainage, and densifies and reinforces the soil in the sense of ground improvement. The integrity of the GCP has been indirectly controlled with the records of each batch including depth and the quantity of stone filled. An integrity testing was attempted using crosshole S-wave logging. The method is conceptionally same as the crosshole sonic logging (CSL) for drilled piers. The only and critical difference is that S-wave should be used in the logging, because P-wave velocity of the stone column is less than that of ground water. The crosshole sonic logger does not have the capability to measure S-wave propagating through the skeleton of crushed stone. An electro-mechanical source, which can generate either P- or SH-waves, and a 1-D geophone were used to measure SH-waves. Two 76mm diameter cased boreholes were installed 1 meter apart across the nominal 700mm diameter stone column. At every 10cm of depth, shear wave was measured across the stone column. One more borehole was also installed 1 meter outward from the one of the above boreholes to measure the shear wave profile of the surrounding soil. The diametric variation of the stone column with respect to depth was evaluated from the shear wave arrival times across the stone column, and shear wave velocities of crushed stone and surrounding soil. The volume calculated with these variational diameters is very close to the actual quantity of the stone filled.

• Geomechanics and Engineering
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• v.4 no.4
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• pp.263-279
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• 2012

The present paper deals with the analysis of combined footings resting on geosynthetic reinforced granular fill overlying stone column improved poor soil. An attempt has been made to study the influence of inclusion of geosynthetic layer on the deflection of the footing. The footing has been idealized as a beam having finite flexural rigidity. Granular fill layer has been represented by Pasternak shear layer and stone columns and poor soil have been represented by nonlinear Winkler springs. Nonlinear behavior of granular fill layer, stone columns and the poor soil has been considered by means of hyperbolic stress strain relationships. Governing differential equations for the soil-foundation system have been derived and solution has been obtained employing finite difference scheme by means of iterative Gauss Elimination method. Results of a detailed parametric study have been presented, for a footing supporting typically five columns, in non-dimensional form in respect of deflection with and without geosynthetic inclusion. Geosynthetic layer has been found to significantly reduce the deflection of the footing which has been quantified by means of parametric study.

• Journal of Korean Society on Water Environment
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• v.25 no.4
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• pp.568-572
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• 2009

The adsorption characteristics of tartrazine by granular activated carbon were experimentaly investigated in the batch adsorber and the packed column. The adsorptivity of activated carbon for tartrazine was largely improved by pH control, and 98 percent of initial concentration could be removed at pH 3. It was estabilished that the adsorption equilibrium of tartrazine on granular activated carbon was sucessfully fitted by Freundlich isotherm equation in the concentration range from 50 mg/L to 1,000 mg/L. The characteristics of breakthrough curve of activated carbon packed column, which depend on the design variables such as initial concentration, bed height, and flow rate, were studied.

• Journal of the Korean Society of Safety
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• v.24 no.4
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• pp.34-39
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• 2009

The adsorption characteristics of amatanth by granular activated carbon were experimently investigated in the batch adsorber and the packed column. The adsorptivity of activated carbon for amaranth were largely improved by pH control, and 94 percent of initial concentration(100mg/L) could be removed at pH 9. It was estabilished that the adsorption equilibrium of amaranth on granular activated carbon was sucessfully fitted by Freundlich isotherm equation in the concentration range from 1mg/L to 100mg/L. The characteristics of breakthrough curve of activated carbon packed column, which depend on the design variables such as initial concentration, bed height, and flow rate, were studied.