• Proceedings of the Korean Geotechical Society Conference
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• 2004.03b
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• pp.667-671
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• 2004

The purpose of this paper is to study on the construction of environmentally friendly roadbed by reinforcing type soil solidification agent. The soil amendment agent used in this study is friendly to the environment, and has a function of soil-cement-agent solidification. The soil amendment agent was admixed with reinforced fiber material for enhancement of strength and durability of roadbed. The project of trial field test of roadbed construction with special reinforcing soil treatment agent was performed in Gyunggido on December 2003. A series of field and laboratory experiments including unconfined compressive strength, permeability were carried out to investigate the physical and mechanical characteristics of solidified roadbed treated by this reinforced solidifying agent. The results of this research showed that the roadbed using normal and poor soil could be efficiently constructed by treatment of this reinforcing type solidification agent admixed with fiber material.

• Proceedings of the Korean Geotechical Society Conference
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• 2004.03b
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• pp.869-872
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• 2004

A study on the solidification of sludge by reactive amendment agent was carried out in this paper. The reactive amendment agent used in this study is mainly composed of inorganic solidification agent and reactive adsorptive material. The reactive agent has a function of soil-cement-agent solidification and harmlessness of contaminant in waste. The reactive agent is environmentally friendly material to the surrounding environment. In this study, a series of tests and experiments including unconfined compressive strength, permeability, pH test, constituent analysis, leaching test were carried out to analyse engineering and environmental characteristics of solidified sludge treated reactive agent. The result of this research shows that the solidified sludge treated reactive agent is increased in strength and decreased in contaminant concentration.

• Steel and Composite Structures
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• v.16 no.1
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• pp.59-75
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• 2014

A new concrete confinement model is developed to predict the axial load versus displacement behavior of circular columns under concentric axial load. The new confinement model is proposed for concrete filled steel tube columns as well as circular reinforced concrete columns with steel tube jacketing. Existing confinement models were evaluated and improved using available experimental data from different sets of columns tested under similar loading conditions. The proposed model is based on commonly used confinement models with an emphasis on modifying the effective confining pressure coefficient utilizing the strength of the unconfined concrete and the steel tube, the length of the column, and the thickness of the steel tube. The proposed model predicts the ultimate axial strength and the corresponding strain with an acceptable degree of accuracy while also highlighting the importance of the manner in which the steel tube is used.

• Geomechanics and Engineering
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• v.6 no.4
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• pp.403-418
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• 2014

There are around 6700 millions tons of perlite reserves in the world. Although perlite possesses pozzolanic properties, it has not been so far used in soil stabilization. In this study, stabilization with perlite and lime of an expansive clayey soil containing smectite group clay minerals such as montmorillonite and nontronite was investigated experimentally. For this purpose, test mixtures were prepared with 8% of lime (optimum lime ratio of the soil) and without lime by adding 0%, 10%, 20%, 30%, 40% and 50% of perlite. Geotechnical properties such as compaction, Atterberg limits, swelling, unconfined compressive strength of the mixtures and changes of these properties depending on perlite ratio and time were determined. The test results show that stabilization of the soil with combination of perlite and lime improves the geotechnical properties better than those of perlite or lime alone. This experimental study unveils that the mixture containing 30% perlite and 8% lime is the optimum solution in stabilization of the soil with respect to strength.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2005.03a
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• pp.361-371
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• 2005

The confined concrete subjected multi-axial stresses have been known as the fact it increases strength of concrete significantly compared with unconfined concrete. Many researchers have studied in confining effects of concrete, and now are studying in many fields. Although many researches about confined concrete using FRP have been studied recently, it is difficult to apply concrete confined by FRP in real structures because FRP is a brittle material. To investigate the influence of concrete strength and ductility increased by confining stiffness in steel, this study was tested and compared with 51 specimens confined by different shapes and thicknesses of steel tube. This test verified the increasement of strength and ductility in confined concrete. Also, analyzing the experimental data by regression method, this study provides stress-strain model about CSS and R4S considering effect of confinement stiffness on the stress-strain relations of concrete.

• Proceedings of the KSR Conference
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• 2007.05a
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• pp.1789-1795
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• 2007

Railroad, the structure maintenance and restoration project was increased and widely performed in concrete pavement road and airport, building at downtown area, bridge abutment, and other concrete structures. Especially, the ground reinforcement technique by quick-reaction expansible resins is the most effective countermeasures against differential settlement and undesired deformation of structure. In this paper, the unconfined compressive strength and some environmental related tests were conducted to evaluate compressive strength and environmental effect of quick-reaction expansive resins and soil mixtures. Also, three case histories of concrete structure and railroad restoration project are presented. Based on the laboratory test, the quick-reaction expansible resins and soil mixture represent the sufficient compressive strength and the leachate material is satisfied the environmental regulation limits. As a result of this study, the structure restoration technology using quick-reaction expansible resins is very effective for restoration of differential settlement and deformation, and it is environmentally sustainable technology.

• 한국지구물리탐사학회:학술대회논문집
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• 2003.11a
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• pp.206-213
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• 2003

Laboratory testing of representative rock specimens is of fundamental necessity for the successful design and/or assessment of facilities associated with many kinds of underground exploitation, including the geological disposal of radioactive nuclear waste. As a fundamental and systematic study, a series of measurements of the physical, mechanical and hydraulic properties of Inada granite and Shirahama sandstone, two rock types that are widely available in Japan, have been performed. This paper presents the results of a study of the effective porosity, density, compressive and shear wave velocity, unconfined compressive strength and permeability of the two rocks. The anisotropy and the effects of confining pressure on the permeability of the rocks, as well as the relationships among the physical, mechanical and hydraulic properties, are also investigated and discussed.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2002.09a
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• pp.28-31
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• 2002

The water level fluctuation (WLF) method is a conventional method for quantifying groundwater recharge by multiplying the specific yield to the water level rise. A 2-D unconfined flow model with a time series of the recharge rate is developed. It is used for elucidating the errors of the WLF method which is implicitly based on the tank model where the horizontal flow in the saturated zone is ignored. Simulations show that the recharge estimated by the WLF method is underestimated for the observation well near the discharge boundary. This is due to the fact that the hydraulic stress resulting from the recharge is rapidly dissipating by the horizontal flow near the discharge boundary Simulations also reveal that the recharge was significantly underestimated with increase in the hydraulic conductivity and the recharge duration, and decrease in the specific yield.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.09a
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• pp.565-569
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• 2003

One-year-long groundwater-level data have been collected from 18 wells in Cheon-an area. The result of barometric efficiency, autocorrelation, cross-correlation and statistical distribution evaluated from the measurement data shows that groundwater-level measurements from observation wells are the principal source of information about aquifer characteristics. Data from WA-2 has high barometric efficiency as well as steady decreasing auto-correlation coefficient, which means nonleaky confined aquifer, Most aquifers in this study show the unconfined properties so that barometric efficiencies are mostly low and the coefficients of cross-correlation between groundwater-level and precipitation are commonly high. This study showed that the long-term groundwater-level monitoring data without artificial stress such as pumping would give accurate information about aquifer characteristics.

• Advances in concrete construction
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• v.9 no.6
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• pp.529-535
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• 2020

The current study investigated experimentally the effectiveness of Carbon Fiber Reinforced Polymer (CFRP) in confining concrete cylinders after being subjected to high temperature. Parameters examined were: (a) the exposing temperatures (20, 100, 200, 400 600 and 700℃) and (b) the number of CFRP layers (1 and 3 layers). A uniaxial compressive testing was carried out on 36 concrete cylinders with dimensions of 150 mm×300 mm. The results obtained show that the compressive strength reduced with the increased of temperature compared to that measured at 20℃. In particular, the reduction in the compressive strength was more observed when the temperature exceeded 400℃. Further, the concrete cylinders confined with one and three layers of CFRP significantly increased the compressive strength compared to the counterpart unconfined specimen tested at the same temperature. Also, the average percentages of the increase in the compressive strength were approximately 112% and 158% when applying 1 and 3 layers of CFRP, respectively, compared to the counterpart unstrengthened specimen tested at the same temperature.