• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2000.04a
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• pp.130-140
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• 2000

The earthquake hazard has been evaluated for 10km by 10km area around Kyeongju which is located near Yangsan fault and has abundant historical earthquake records. The ground motion potentials were determined based on equivalent linear analysis by using the data obtained from in situ and laboratory tests and the El centro eartqhuake record scaled to CLE and OLE of the region. The in situ tests include 9 boring investigations 2 crosshole 7 downhole 13 SASW tests and in the laboratory X-ray diffraction analyses and resonant column tests were performed. The peak ground accelerations range between 0.140g and 0.286g on CLE and between 0.051g and 0.116g on OLE respectively showing the good potential of amplification in the deep alluvial layer which is common in Kyeongju area. the response spectrum based on the Korea design guide was sometimes underestimate the motion. particularly near the natural period of the site and the importance of site-specific analysis and need for the improved site categorization method were introduced.

• Proceedings of the Korean Geotechical Society Conference
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• 2002.11b
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• pp.103-114
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• 2002

Stability of cut-slope is considered to have a deep relationship with rock types since rock has its own engineering and geological characteristic such as shear strength, durability, weathering profile, geological structures. Therefore, analysis of geological and engineering characterisics of rock mass is essential for the evaluation of rock slope stability This paper introduces the statistical data of slope failure cases which was collected from highway slopes constructed in sedimentary rock mainly of shale in Ky ng-sang Basin. Primary failure feature in this area is planar failure along the bedding regardless of slope geometry. Even a disasterous slope failure case due to the thick clay layer between the beddings was reported. Failures and rock fall were reported to ocurred frequently after the completion of cutting due to the weathering, so long-term slope stability should be considered as a important factors in design.

• Proceedings of the Korean Geotechical Society Conference
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• 1999.03a
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• pp.97-104
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• 1999

This case study has been prepared to provide the practical data about construction of temporary shoring facilities (i.e. braced sheet pile excavation) and to utilize the case study information effectively for design and construction of future facilities. This case study includes information such as 1) installing measurement devices to monitor the deformation of the sheet pile walls and the subsoil in the vicinity after establishing the criteria for the sheet pile deflection; 2) monitoring the actual movement of the temporary facility after setting up the survey control standard (due to the movement of the temporary facility) : 3) inspecting the suitability of the temporary facility construction: and 4) analyzing and studying the result of the tension test after installing ground anchors.

• Proceedings of the Korean Geotechical Society Conference
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• 1999.03a
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• pp.259-266
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• 1999

In case that pile cap is in direct contact with underlying soil, the bearing mechanism for pile groups, including direct bearing effect of cap and its induced influence on pile-soil-cap interaction, should be properly considered. In this paper, the effects of pile caps on behaviors of pile groups in sandy soils were investigated by model tests, which consist of tests on 3 by 3 pile groups with/without contact on subsoil, single pile with/without contact and cap as a shallow foundation. Also, the influences of pile spacing in group piles on contact effects were investigated. The test results showed that the load carrying capacity of pile cap was large enough not to be ignored. However, the interaction effects due to contact between cap and subsoils were not revealed obviously in working load range. And in the design of pile groups, the bearing effect of pile cap when contacted with subsoils, can be reflected by simply summing up load settlement behaviors of each cap and group piles without contact.

• Proceedings of the Korean Geotechical Society Conference
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• 1999.03a
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• pp.153-158
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• 1999

In the design and analysis of soil nailed slope, interaction between soil and nail is one of important problems. In the present analysis approaches for the interactions have developed a elastic analysis approach or a plastic analysis approach. However these approaches are not able to estimate the general interaction between soil and nail. In this study the general interaction between soil and nail using the strain wedge model is proposed. Also results of comparison between the proposed method and full scale test results by Gassler(1976) and large scale experimental results at Oxford University are shown in good agreements.

• Proceedings of the Korean Geotechical Society Conference
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• 1999.03a
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• pp.137-144
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• 1999

Recently a removable soil nail is demanded due to problems beyond of economical and engineering purpose. In this study removable soil nails are developed and field pull-out tests are carried out 16 times in order to analysis pull-out characteristics of the removable soil nail. For the spacing and the installed position of fixed socket, the length of the soil nail, and W/C ratio of cement grout in the removable soil nail, pull-out characteristics of pull-out tests are analyzed. From the pull-out characteristics of removable soil nails, it is found that the spacing of fixed socket and W/C ratio of cement grout are important design parameters.

• Proceedings of the Korean Geotechical Society Conference
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• 1999.03a
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• pp.129-136
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• 1999

The use of strut preloading method is gradually increasing in braced excavations in Korea. And it is necessary to analyse the effects of strut preloading on the wall deflection, bending moment and strut axial force etc. In this study, by using the analysis method of beams on elasto-plastic foundations, parametric studies of correlation between preloading and earth retaining structures in sandy soils were peformed in strut preloading application. As results, about 50% of design strut load was effective as a preloading force in considering the displacement and member forces of structures. And at least the effective stiffness of strut should be over 25% of the ideal value in order to restrain the excessive increase of wall deflection and bending moments. In order to protect excessive movements in braced excavation, to preload the strut was rather effective way than to increase the stiffness of strut and braced wall, but the excessive axial force of strut should be checked simultaneously.

• Proceedings of the Korean Geotechical Society Conference
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• 1999.11c
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• pp.11-20
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• 1999

The method which makes the soft ground reinforced by using the geogrid, a kind of geosynthetics has been getting popular and its usefulness also has been increased due to reduction in costs, ease of construction and great exterior view, But the study on the frictional characteristics, which is the important factor in design, between reinforcement and soil is insufficient. In this study, compaction degrees were considered through large-scale pullout tests. As a part of studying on estimation of pullout frictional characteristics between soil and geosynthetics, pullout tests were peformed and from the result of pullout tests, pullout frictional parameters between soil and geosynthetics were obtained and pullout behaviors were learned.

• Proceedings of the Korean Geotechical Society Conference
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• 2003.03a
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• pp.561-568
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• 2003

The protection of adjacent structures in urban excavation has been an important issue. But the research on the interaction between ground movements and adjacent structure has been scarce, therefore this study was necessitated. Current design practice for the prediction of excavation-induced ground movements heavily rely on empirical method. In this study, damage levels of brick building are examined closely by means of angular distortion, deflection ratio, horizontal strain. The results of numerical analysis indicated that the movement of actual building was 60∼65% of the ground movement, while angular distortion was 45∼65%. Also numerical analysis for the assessment of brick building can be applied to the building protection at various construction stages.

• Proceedings of the Korean Geotechical Society Conference
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• 2003.03a
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• pp.153-160
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• 2003

While the interests on the environmental problem during the construction are increasing, the use of low noise-vibration auger-drilled pilling is increasing to solve noise and vibration problem in pilling. Therefore, in Korea, SIP(Soil-Cement Injected Precast Pile) method is mainly used as auger-drilled pilling. However, there is no proper design criteria compatible with the ground condition of Korea, so which is most wanted. To improve and supplement this situation, direct shear tests between SIP pile skin interface and soil were executed on various conditions. Through the analysis of test results, skin resistance characteristics of SIP were investigated thoroughly. Also, the nonlinear unit skin resistance capacity model with SM, SC soil were suggested.