• Journal of the Korean Geotechnical Society
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• v.29 no.8
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• pp.15-25
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• 2013

In order to examine the unsaturated shear strength characteristics of compacted weathered gneiss soils, the constant water content compression (CWCC) test was carried out. Specimens were made by static compaction under two densities conditions. The shear behavior in accordance with an initial suction obtained by varying initial degrees of saturation was evaluated. The suction could be directly measured by the use of the ceramic disk and the pore-water pressure transducer. The results of the peak shear strength from the CWCC test were examined using the relationship with Mp line from triaxial test under the saturated state, that is, by means of the suction stress which was calculated using the measured suction. In addition, the applicability of the suctions stress to the unsaturated shear behaviour of compacted weathered gneiss soils was discussed by applying Suction stress-SWCC Method (SSM).

• Journal of the Korean Geotechnical Society
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• v.29 no.6
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• pp.33-51
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• 2013

This paper introduces the improvement of connection method for segment in tunnel lining system using prestressed steel cable and presents the results of real-scale tests. It conducted a study about the applicability and mechanical behaviour analysis of the new method that connects segment tunnel lining using prestressed steel cable by real-scale test. Through the research, it was found that the new method has stronger connection than conventional assembling methods. Also, the new method can be expected to have integrated behavior and stability increase of shield tunnel lining. It is considered that the new method is much more effective than conventional assembling methods.

• Journal of the Korean Geotechnical Society
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• v.34 no.4
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• pp.49-55
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• 2018

A pre-load of bracing was imposed to prevent the horizontal displacement on the strut of the braced wall adjacent to the building during the ground excavation. For this purpose, large scale model tests were conducted, without and with pre-load on braced wall. Adjacent building load was also imposed in different locations, that were 0 m, 1D, 2D on ground surface. In this study, model tests in 1:10 scale were performed in real construction sequences, and adjacent building was 12 m in width and the size of model test pit was 2 m in width, 6 m in height, and 4 m in length. As a result, it was found that the stability of the existing building adjacent to the braced wall within Rankine's active zone could be greatly enhanced when the horizontal displacement of the braced wall was reduced by applying a pre-load. which was larger than the designated axial force on the strut of the braced wall.

• Journal of the Korean Geosynthetics Society
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• v.8 no.4
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• pp.19-25
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• 2009

In this study, field pull-out tests were performed for steel pipe nailing installed foldable wedge and non-wedge type steel pipe nailing under the same test conditions. This is to evaluate pull-out resistance improvement effect of steel pipe nailing installed foldable wedge. Evaluating for field pull-out characteristics of steel pipe nailing installed foldable wedge was performed through analysis of ultimate pull-out resistance ($T_L$), ultimate unit skin friction ($q_s$, $u_{max}$), tensile normal stiffness ($K_{\beta}$), tension of nail. As a result, the steel pipe nailing installed foldable wedge have an effect of pull-out resistance increased about 30% in comparison with non-wedge type steel pipe nailing.

• Proceedings of the Korean Geotechical Society Conference
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• 2000.11a
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• pp.603-606
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• 2000

The cost needed for the construction and management of highways in the whole nation is rapidly growing so the research that can decrease the cost is required. However, most of the highway specs have simply converted from those of other countries, including USA. Therefore, some of our design and construction specs were not the optimum ones based on our own situation, requiring a research under the actual traffic and environment of our nation. The use of test road develops many aspects of highway engineering. Those are evaluation of construction materials, a general overview of korea pavement design and serviceability under the actual traffic and environmental condition of the nation. It is also economical and efficient compared to the trial construction of each item in spreaded form. A test road, 7.7km long with two lanes, is being constructed on the Inner Central Expressway. In this test road, 2.7km is planned for asphalt pavement and 3.4km is planned for concrete pavement. Three test bridges and five earth retaining structures will be included in the test road. Based on the master plan, the major performance was progressing such as detailed research modules of each area, preliminary research for the future research, sensor surveys for the behavior analyses of pavements and structures with installation methods and data acquisition systems, the foundation research of Integrated Instrumentation System and the Management Plan for automated measurement. Some area(structure research division, geotechnical research division) was designed the instrumentation plan because some instrument sensors must be installed during the construction of the test road. And then the instrumentation plan of each area was enforcing because a large majority of the instrument sensors must be installed after the construction of the test road. The field surveys with material property tests and pilot instrumentation test with sensor tests was also performing in accordance with the construction in the field.

• Journal of the Korean Geotechnical Society
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• v.19 no.1
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• pp.31-40
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• 2003

Current design of pile group is based on the estimation of the overall bearing capacity of a pile group from that of a single pile using a group efficiency. However, the behaviors of a pile group are influenced by various factors such as the method of pile installation, pile-soil-pile interaction, cap-soil-pile interaction, etc. Thus, it is practically impossible to take into account these factors reasonably with the only group efficiency. In this paper, a new method for the design of pile groups is proposed, where the significant factors affecting the behavior of a pile group are considered separately by adopting several efficiencies. Furthermore, in the proposed method, the load transfer characteristics of piles and the difference of pile behaviors with respect to the pile locations in group can be taken into account. The efficiencies for the method are determined using the settlement failure criterion, which is consistent with the concept of allowable settlement fur structures. The efficiencies calculated from the results of existing model tests are presented, and the bearing capacity of a pile group in the other model test is calculated and compared with that from the test result to verify the validity of the proposed method.

• Journal of the Korean Geotechnical Society
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• v.15 no.5
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• pp.157-170
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• 1999

A new design technique is presented to stabilize cut slopes in cohesive soils by use of piles. The design method can consider systematically factors such as the gradient and height of slope, the number and position of pile's rows, the interval and stiffness of piles, etc. The design method is established on the basis of the stability analysis of slope with rows of piles. The basic concept applied in the stability analysis is that the soil across the open space between piles can be retained by the arching action of the soil, when a row of piles is installed in soil undergoing lateral movement such as landslides. To obtain the whole stability of slope containing piles, two kinds of analyses for the pile-stability and the slope- stability must be performed simultaneously. An instrumentation system has been installed at a cut slope in cohesive soil, which has been designed according to the presented design process. The behavior of both the piles and the soil across the open space between piles is observed precisely. The result of instrumentation shows that the cut slope has been stabilized by the contribution of stabilizing effect of piles on the slope stability in cohesive soil.

• Journal of the Korean Geotechnical Society
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• v.15 no.5
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• pp.171-191
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• 1999

The final aim of this research is to systematize the reinforced-earth wall system using the geosynthetic composite reinforcement in the weathered granite backfill soils having relatively large amount of fines. As a staged endeavour to accomplish this purpose, laboratory pull-out tests and finite element modeling are carried out in the present study focusing on the analyses of friction characteristics associated with interaction behaviors of the geosynthetic composite reinforcement composed of geogrid with a superior function in tensile resistance and geotextile with sufficient drainage effects. In addition, drainage effects of the geotextile below geogrid are examined based on the analysis of finite difference numerical modeling. From the present investigation, it is concluded that the geosynthetic composite reinforcement in the weathered granite backfills may possibly be used to achieve effects on both a reduction of deformations and an increase of the tensile resistance, together with drainage effects resulting from the geotextile.

• Journal of the Korean Geotechnical Society
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• v.15 no.5
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• pp.259-279
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• 1999

Model tests on propped retaining walls were performed for the investigation of wall displacement, distribution of earth pressure, surface settlement and underground movement at various excavation stage in sand. The result of model tests on the trough of surface settlement showed considerable difference depending on the characteristic of wall stiffness, wall friction and soil condition. The location of maximum underground movement were found to be at range of 0.15H to 0. 1H(H: Final excavation depth). Effect of arching by the redistribution of earth pressure were closely related to the stiffness of wall as well as the soil condition. The wall displacement and earth pressure distribution were simulated by elasto - plastic beam analysis program and finite element method with GDHM model respectively. The result of elasto-plastic analysis showed some discrepancy on the wall displacement and earth pressure, but result of underground movement by FEM with various wall stiffness were in good agreement with the model tests.

• Journal of the Korean Geotechnical Society
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• v.15 no.5
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• pp.291-300
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• 1999

Surfactant flushing for enhancing the removal of BTEX from contaminated sand/clay mixtures was investigated. Eight soil columns packed with relatively undisturbed BTEX contaminated soils, were leached with water, methyl alcohol and then flushed with surfactant with or without several additives. Initial concentrations of BTEX mixture range from 278mg/kg to 1975mg/kg. Initial BTEX removal efficiency was 98% when the contaminated soil was flushed with water of 850 pore volumes. Because of tailing effect, water flushing could not remove below 8mg/kg concentrations during the experimental period. Eventually, the most effective surfactant for flushing was turned out to be 4% SOFTANOL(equation omitted)-90 with 3% ethyl alcohol and 3% SXS. In interrupted flow conditions, the removal efficiency was 99.5% with the flushed water of 95 pore volumes. The BTEX mixture removed from the soil columns during the surfactant flushing ranges from 84.5% to 99.5% of the initial amount for both water leaching(850 pore volumes) and surfactant flushing(95-165 pore volumes), respectively. Test results indicated that surfactant flushing could enhance the removal of BTEX mixture from contaminated soils and could reduce the aqueous phase BTEX mixture concentration in leachate.