• Journal of the Korean Society for Railway
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• v.3 no.1
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• pp.34-41
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• 2000

The analysis of static and dynamic characteristics of reinforced roadbed materials was performed through model and laboratory tests. The strength characteristic of reinforced roadbed materials such as HMS-25 and soil were investigated through the unconfined axial compression test, the model soil box test and the combined resonant column and torsional shear test. The unconfined axial compression strength of HMS-25 shows a steady increasement in strength due to the chemical hardening reaction between HMS-25 and water. The result of model soil box test reveals that railroad roadbed of HMS-25 is better than that of soil in several aspects, such as, bearing capacity and settlement. The combined resonant column and torsional shear test result indicates that shear modulus of HMS-25 and soil increase with the power of 0.5 to the confining pressure and linear relationship to normalized shear modulus and damping ratio.

• Journal of the Korean Geosynthetics Society
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• v.22 no.4
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• pp.83-92
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• 2023

In this study, we conducted verification of key influencing factors during cone penetration testing using the developed Mini Cone Penetration Tester (Mini-CPT), and compared the experimental results with empirical formulas to validate the equipment. The Mini-CPT was designed to measure cone penetration resistance through a Strain Gauge, and the resistance values were calibrated using a Load Cell. Moreover, the influencing factors were verified using a model ground constituted in a soil box. The primary influencing factors examined were the boundary effect of the soil box, the distance between cone penetration points, and the cone penetration speed. For the verification of these factors, the experiment was conducted with the model ground having a relative density of 63.76% in the soil box. It was observed that the sidewall effect was considerably significant, and the cone penetration resistance measured at subsequent penetration points was higher due to the influence between penetration points. However, within the speed range considered, the effect of penetration speed was almost negligible. The measured cone penetration resistance was compared with predicted values obtained from literature research, and the results were found to be similar. It is anticipated that using the developed Mini-CPT for constructing model grounds in the laboratory will lead to more accurate geotechnical property data.

• Journal of the Korean Geosynthetics Society
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• v.11 no.4
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• pp.45-53
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• 2012

Ground drilling is a common method to conduct site investigation, soil improvement, and pile installation. In the point of construction ground drilling requires electrical energy to drill a hole in ground in which the energy exerts into the motor located on the head of auger and generates rotational power. In this paper it is verified that the exerted electrical energy is closely related to the strength characteristics of ground. Measurement sensors, recording system, and drilling system were developed to obtain exerted motor current and drilling depth and laboratory soil box tests were carried out. The measured motor current and boring depth were applied to predict SPT N-value and the prediction results were compared to SPT N-value of laboratory tests. The test results show that the exerted electrical energy to bore ground be a good index to estimate SPT N-value.

• Geomechanics and Engineering
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• v.11 no.5
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• pp.625-638
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• 2016

This paper presents field study and numerical modeling results for a single-cell low-fill concrete box culvert under a flexible pavement subjected to traffic loading. The culvert in the field test was instrumented with displacement transducers to capture the deformations resulting from different combinations of static and traffic loads. A low-boy truck with a known axle configuration and loads was used to apply seven static load combinations and traffic loads at different speeds. Deflections under the culvert roof were measured during loading. Soil and pavement samples were obtained by drilling operation on the test site. The properties of the soil and pavement layers were determined in the laboratory. A 3-D numerical model of the culvert was developed using a finite difference program FLAC3D. Linear elastic models were used for the pavement layers and soil. The numerical results with the material properties determined in the laboratory were compared with the field test results. The observed deflections in the field test were generally smaller under moving loads than static loads. The maximum deflections measured during the static and traffic loads were 0.6 mm and 0.41 mm respectively. The deflections computed by the numerical method were in good agreement with those observed in the field test. The deflection profiles obtained from the field test and the numerical simulation suggest that the traffic load acted more like a concentrated load distributed over a limited area on the culvert. Elastic models for culverts, pavement layers, and surrounding soil are appropriate for numerical modeling of box culverts under loading for load rating purposes.

• Journal of the Korean Geotechnical Society
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• v.26 no.8
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• pp.5-14
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• 2010

To simulate two-dimensional plane-strain conditions in the laboratory model test, the side frictional resistance between the soil and thick glass or plastic sheet of the soil container should be reduced as much as possible. However, in fact this side friction cannot be removed completely. In this paper, the ground model simulated as a multi-sized aluminium rod mixture was introduced to get rid of the side frictional resistance and applied to the laboratory shear box test. In addition, an application of the close range photogrammetric technique to the shear box test was validated. As a result, it was found that a mean value of dilation angle from the close range photogrammetry was close to the dilation angle defined by the curve of shear strain vs. volumetric strain.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.974-981
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• 2005

Because general laboratory tests for sand compaction pile method including unit-cell test device have fixed outside diameter, as area replacement ratio increase, diameter of sand pile increase. These condition can bring about overestimation of stiffness of composite ground. In addition, existing large soil box which consist of bellows type loading plate can occur serious mistake in checking the amount of drained water because there are additional drainage along the inside wall in device. Overcoming these shortcoming, this paper developed modified large scale soil box consist of piston type load plate. In this study, using this device, series of modified large scale soil box tests were performed, and investigated the settlement and stress transportation characteristics with area replacement ratio in sand compaction pile method.

• Proceedings of the Korean Geotechical Society Conference
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• 2003.06a
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• pp.145-154
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• 2003

When a nail pulled out in dense, granular soil, the soil in the vicinity of the nail tends to dilate, but its dilatancy results in a normal stress concentration at the soil/nail interface, thereby increasing the pull-out resistance of the inclusion. It is thought to be occurring within the resistance zone where the soil mass is at stationary state and the reinforcement are held in position by the soil, due to the friction or bond. In this paper, A series of direct shear and interface tests were conducted by using so called‘Constant Normal Stiffness Test Apparatus’which was modified and improved from the conventional direct shear box test rig. Unlikely the normal shear box test, this enables to simulate the different constraint effects of surrounding soil during shear under the conditions of constant stress and volume, constant normal stiffness. The aim of the research programme is to get better understanding of pull-out bond mechanism, thus to explore the possibility of evaluating the pull-out bond capacity of soil/reinforcement at the preliminary design stage from the laboratory test.

• Journal of Korean Society of Rural Planning
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• v.5 no.1 s.9
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• pp.45-55
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• 1999

The applicability of resistivity cone for contaminant investigation in farm land was examined in laboratory and in-situ. To verify the resistivity variations in sand with contaminants, laboratory experiment used soil resistivity test box was performed. Heavy metal and others ions were appeared steep variations in low concentration. Pilot test results were the same as laboratory test results. In the in-situ test used resistivity cone, resistivities of waste landfill layer were low than the common soil layers and resistivities had been difference with concentration of contaminant components. Therefore contaminant investigation in farm land using resistivity cone was expected very effective.

• Journal of the Korean Geotechnical Society
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• v.16 no.1
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• pp.157-165
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• 2000

The applicability and performance of HMS-25 as the railroad roadbed materials were evaluated through the model and laboratory tests. The uniaxial compression test of HMS-25, model soil box test, and combined resonant column and torsional shear test were performed for static and dynamic analysis of railroad roadbed. The uniaxial compression test result of HMS-25 shows steady increase in strength due to hardening chemical reaction between HMS-25 and water. The result of model soil box test reveals that railroad roadbed of HMS-25 is better than that of soil in several aspects such as bearing capacity and settlement. The combined resonant column and torsional that shear test result indicates that shear modulus of HMS-25 increases with the power of 0.5 to the confining pressure and that shear modulus increases with the increase of curing period.

• Journal of The Korean Society of Agricultural Engineers
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• v.48 no.5
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• pp.73-80
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• 2006

The mono-layer cover system is composed of soils only as a filling material and various plants are planted on the surface to control the water balance in the cover system. In this paper, the mono-layer cover system was considered as an alternative landfill final cover system and developed a model that could utilize industrial by-product (especially, coal ash & phosphogypsum) as additive filling materials. The mixture of granite soil, coal ash, and phosphogypsum was placed as a cover material in a box constructed with cement. Laboratory tests were carried out to investigate the environmental effect on the utilization of coal ash & phosphogypsum and to determine the mxing ratio of each materials. In the leaching test, all materials showed lower heavy metal concentration than the threshold values of regulation. The optimum mixing ratio of materials which was applied to field model test was determined to soil (4) : coal ash (1) : phosphogypsum (1) on the volume base. Field model tests were continued from February to July, 2004 in the soil box that was constructed with cement block. It was verified that coal ash and phospogypsum mixed with soil was to be safe environmentally and the water balance of mono-layer cover system was reasonable.