PBT에 의한 직접기초의 안정성 평가

기완서 ( Wan Seo Ki ),주승완 ( Seung Wan Joo ),김선학 ( Sun Hak Kim ) 대한지질공학회 2005 지질공학 Vol.15 No.4

직접기초의 설계 및 안정성 평가를 위해 편마암 풍화토로 구성된 A, B 대상현장에서 평판재하시험을 실시하여 이론적, 경험적 지지력 공식 및 여러 침하량산정공식에 대한 비교·분석을 실시하였다. 또한, 편마암의 풍화토지반에 실시되어진 평판재하시험의 결과를 이용한 효율적인 안정성 평가방법을 고찰하였다. 그 결과 허용지지력은 Terzaghi의 이론공식이 평판재하시험 결과에 비교하여 과대하게 산정 되어지는 것으로 나타났으며, 직접기초 설계시 국내에서 가장 널리 이용되고 있는 Terzaghi-Peck 방법이 침하량이 크게 나타나 안정적인 설계를 하는데 효과적으로 나타났다. 또한, 편마암의 풍화토 지반에 실시된 평판재하시험결과 하중-침하 곡선에서 얻어진 지지력으로 안정성을 검토하는 경우 침하량 관점보다 더 안전측으로 평가되어짐을 알 수 있었다. For the design of spread foundation and the stability evaluation, we compared and analyzed it for theoretical, empirical bearing capacity formulas, and various settlement computation formulas, by conducting the plate bearing test at the site of A and B, which consisted of gneiss weathered soil. In addition, we considered the effective method of stability evaluation by carrying out the plate bearing test carried out on the ground consisted of weathering soil of gneiss. Consequently, it was found out that the allowable bearing capacity by the theoretical formula of Terzaghi was too excessive in comparison with the result of the plate bearing test and the Terzaghi-Peck method, which was used widely domestically in designing the spread foundation. It was more effective for a stable design. As a result of the plate bearing test carried out, on the ground consisted of weathering soil. It was found that reviewing the stability by the bearing capacity calculated with load-settlement curve. It is evaluated in a safer side than the point of view of the settlement.

치환공법을 적용한 연약지반에 시공된 보강토옹벽의 거동해석

기완서 ( Wan Seo Ki ),주승완 ( Seung Wan Joo ),김선학 ( Sun Hak Kim ) 대한지질공학회 2007 지질공학 Vol.17 No.4

연약지반에 보강토옹벽을 시공 시 거동에 영향을 주는 인자로 기본적인 물성뿐만 아니라 보강토옹벽에 의한 하중증가와 압밀기간, 간극수압 등의 영향을 받는 것으로 보고되고 있다. 본 연구에서는 보강토옹벽과 연약지반의 거동해석에 지반해석 프로그램인 SAGE CRISP를 이용하여 수행하였다. 첫 번째로 보강토옹벽의 과도변위를 개선하기 위한 치환공법의 거동 개선 효과를 검토하였으며, 두 번째로 치환공법을 적용 후 보강토옹벽의 배면에 보강재 수직설치간격이 지반의 거동에 미치는 영향을 비교·분석하였다. 마지막으로 치환공법을 적용 시 적정 치환 폭과 깊이를 제안하고자 하였다. 치환공법이 보강토옹벽의 거동 개선에 상당한 효과가 있음을 알 수 있었으며, 보강재 수직설치간격은 옹벽상단의 수평변위개선효과가 있는 것으로 나타났으나 하단의 수평변위와 옹벽배면의 수직변위 개선효과는 미소한 것으로 나타났다. 또한 치환폭의 증가에 따른 수평·수직변 개선효과는 크지 않은 것으로 나타나 치환폭의 증가는 불필요함을 알 수 있었으며, 적정 치환깊이는 연약층의 두께에 대한 옹벽높이의 비(H/T)에 따라 옹벽높이에 대한 치환깊이의 비(D/H)로 제안하였다. It is reported that factors affecting the behavior of reinforced earth retaining walls built on soft ground are not only basic physical properties but also the increase of load by the reinforced earth retaining walls, consolidation period, pore water pressure, etc. This study analyzed the behavior of reinforced earth retaining walls and soft ground using SAGE CRISP, a ground analysis program. First, we examined the effect of the replacement method, which was to prevent the excessive displacement of reinforced earth retaining walls, in improving the behavior of the walls. Second, we compared and analyzed how the behavior of ground is affected by the vertical interval of stiffeners on the back of reinforced earth retaining walls after the application of the replacement method. Lastly, we proposed the optimal replacement width and depth in the application of the replacement method. The results of this study proved that the replacement method is considerably effective in improving the behavior of reinforced earth retaining walls. In addition, the vertical interval of stiffeners on the back of reinforced earth retaining walls appeared effective in improving the horizontal displacement of the top of retaining walls but not much effective in improving the vertical displacement of the back of retaining walls. In addition, improvement in horizontal-vertical displacement resulting from the increase in replacement width was not significant and this suggests that the increase of replacement width is not necessary. With regard to an adequate replacement depth, we proposed the ratio of replacement depth to the height of retaining walls(D/H) according to the ratio of the thickness of the soft layer to the height of retaining walls(H/T).

포준,일정변형률속도 압밀시험을 이용한 해성점토,화강암질 풍화토의 압밀특성에 관한 연구

기완서 ( Wan Seo Ki ),주승완 ( Seung Wan Joo ),김선학 ( Sun Hak Kim ),심태섭 ( Tae Sup Shim ) 대한지질공학회 2002 지질공학 Vol.12 No.4

퍼지근사추론법에 의한 암반사면의 안정해석

기완서 ( Wan Seo Ki ),김삼석 ( Sam Seok Kim ),주승완 ( Seung Wan Joo ) 대한지질공학회 2001 지질공학 Vol.11 No.2

점추정법에 의한 암반사면의 안정성해석 모델

심태섭 ( Tae Sup Shim ),주승완 ( Seung Wan Joo ) 대한지질공학회 2000 지질공학 Vol.10 No.2

고압분사주입공법으로 보강된 개량체의 특성 및 흙막이벽의 변형해석

심태섭 ( Sim Tae Sup ),주승완 ( Joo Seung Wan ) 한국농공학회 2000 韓國農工學會誌 : 전원과 자원 Vol.42 No.6

Recently, the construction method of high pressure jet-grouting is in wide-use, for the purpose of structure foundation ground, reinforcing of ground behind propped retaining walls and cut-off in order to perform safe construction of underground excavation work. This study was performed a serious of tests of field permeability and unconfined compressive strength upon ground improved established on the ground behind propped retaining walls and examined proper jet mechanism by changing the construction parameter value of high pressure jet-grouting. In addition, we got the conclusion like the followings as a result of inspecting the condition of earth pressure distribution and deformation, using elasto-plastic method and FEM. 1. In that characteristics of strength of ground improved, with the same condition of construction parameter, unconfined compressive strength of sand gravel is shown bigger than that of silty sand by about 1.6 times and cut-off effect is shown to have effect of reducing the permeability of original ground by about 10^-2~10^-3cm/s. 2. As a result of analysis of figures of horizontal displacing quantity of propped retaining walls materials regarding before and after High pressure jet- grouting through FEM, the reducing quantity of 0.1~0.3mm in maximum horizontal displacement is shown.

강우에 따른 화강암질 풍화토 사면의 전단강도 특성에 관한 연구

심태섭 ( Tae Sup Shim ),김선학 ( Sun Hak Kim ),기완서 ( Wan Seo Ki ),주승완 ( Seung Wan Joo ) 대한지질공학회 2004 지질공학 Vol.14 No.4

화강암질풍화토(SP, SM)로 축조된 사면에 사면경사·강우강도에 따른 사면 내 간극수압, 침투깊이, 강도정수를 산정하였다. 그리고 불포화토의 전단강도 식을 적용하여 강우에 따른 전단강도의 변화를 비교·분석하였다. 그 결과 강우에 따른 침투속도는 강우강도가 클수록, 사면의 완만할수록 침투가 빨리 진행되었다. Lumb의 이론치와 모형실험의 실측치를 비교분석한 결과 실측치가 더 빠른 것을 알 수 있었다. 그리고 SM은 SP에 비해 전단강도가 크게 나타나는데 세립분이 증가할수록 투수계수가 작아지고 침투율이 작아짐에 따라 침투속도에 영향을 주는 것을 알 수 있었다. 또한, 사면 내 전단강도는 1:1.5의 경사에서 가장 작은 전단강도를 보이는데 간극수압의 상승으로 인하여 저하되는 것으로 나타났다. This study calculated the pore water pressure, the depth of seepage, the constant of the strength in accordance with the slope inclination and the rainfall intensity over the slope built by the weathered granite soil (SP, SM). And, the change of the shear strength in accordance with the rainfall has been compared and analyzed by applying the shear strength formula of the unsaturated soil. As a result, the rainfall intensity is stronger and the slope inclination is gentler the seepage speed in accordance with the rainfall became faster proportionally. As a result of comparing and analyzing both the theoretical value of Lumb and the actual value of the model, it can be said that the actual value is faster. Since SM shows the bigger shear strength than SP, it can also be said that as the granules increase, the coefficient of permeability becomes smaller; and as the seepage rate became smaller, it affects the seepage speed. Likewise, the shear strength within the slope displays the smallest shear strength at the inclination of 1:1.5 the reason of its decrease turned out that it was due to the increase of the pore water pressure.

이방향으로 채취된 재성형 해성점토의 압밀특성

김선학(Kim Sun-Hak),심태섭(Shim Tae-Sup),기완서(Ki Wan-Seo),주승완(Joo Seung-Wan) 대한토목학회 2002 대한토목학회 학술대회 Vol.2002 No.11

암반사면의 안정성과 평가 및 적용에 관한 연구

주승완,윤선호 서강정보대학 2002 論文集 Vol.21 No.-

In general the evaluation process of rock slope stability is an ambiguous system which is made up of ideas subjected to practical experience of an expert. This paper aims to propose more effective methods that helps engineers to evaluate the stability of rock slope by using RMR(Rock Mass Rating for the Geomechanics Classification) and Stereographic Projection and Fuzzy Approximate Reasoning Concept.

철근콘크리트에 교량의 중성화에 관한 연구

주승완,윤선호 서강정보대학 2001 論文集 Vol.20 No.-

In this study, 25 bridges which material-age was from 10 years to 30 years in Chonnam province were examined for neutralization test in order to obtain durability by examining neutralization. The mechanism of carbonation and influencing factors to the carbonation by considering the depth and the speed of carbonation are compared with data measured from field tests. Based on the analysis and comparison, the range of carbonation speed coefficient is proposed and the relationship between carbonation depth and remaining lifetime is predicted. This study aims to provide the reference data, which will calculate lifetime of Reinforced concrete bridge and utilization of carbonation factors.