터널 3 차원 계측 및 분석기법을 적용한 전방 지반거동 예측

구자갑,Gu, Ja-Gap 한국건설안전협회 2008 建設 安全技術 Vol.44 No.-

Alberta대학교의 Geotechnical centre의 소개

구자갑 한국구조물진단유지관리공학회 2003 한국구조물진단유지관리공학회 논문집 Vol.7 No.3

경사지반 쌓기비탈면에서의 압성토공법 적용

구자갑,이동이 한경대학교 2009 論文集 Vol.41 No.-

When rails or roads are being extended or installed, it is possible that sloped areas needs banking. If soft grounds are near by sloped areas, the loads of banked slopes can be transmitted to soft grounds and collapse might occur due to base failure. In order to prevent base failure, counterweight fill can be applied on top of banked slopes. In this case, the in-situ ground of the banked slope must be horizontal in order to decide the size of counterweight fill. However, there are more cases that bank must take place on top of slope. In this case, the body force that was banked on top of the slope is different, compared to when banked on horizontal ground. Therefore, size can not be decided by the established method. Therefore, this study is to present ways to decide the size counterweight fill when applied to slope by using the angle of in-situ ground.

상재하중의 영향을 고려한 Diaphragm Wall의 3차원 안정도 해석

구자갑,이상덕,전몽각,Gu, Ja-Gap,Lee, Sang-Deok,Jeon, Mong-Gak 한국지반공학회 1991 지반 : 한국지반공학회지 Vol.7 No.3

굴착 중 slurry로 지대되고 있는 상태에서 지하수와 상재하중의 영향을 고려한 diaphragm wall 의 안정도를 해석하기 위하여 Belt Piaskowski/kowalewski, Washbourne의 모델을 확장하고, 확장된 이론으로 프로그램 SL3D를 개발하였다. Washbourne의 모델에서는 Bell, Piaskowski / Kowalewski의 모델에 비해, 굴착깊이가 증가함에 따라 안정도가 매우 큰 폭으로 증가하고, 비교적 초기굴착단계에서 부터 안전측에 속한다. 또한 slurry의 밀도, 지하수위, 흙의 내부마찰각, trench의 길이,상재단위하중등이 안정도에 미치는 영향을 분석하였고, 이것을 근거로 nomogram을 작성하였다. To analyze the effects of ground water levels and external loads on the stability of a Dia- phragm wall, the three models of Bell, Piaskowski/kowalewski, and Washbourne were modified and extended to develop a new program SL3D. Comparing to the other two models, Washbourne's model shows the stability in on safes at the beginning of the excavation and increase as the excavation continue . Also the effects of various design factors, such as the density of slurry, ground water levels, the friction angle of soil, external loads and the length of trench, have been analyzed and a nomogram was developed.

국내 다층지반의 지반물성치 및 토압에 관한 고찰

구자갑,김운학,최정호,유영화,정양규 한경대학교 2004 論文集 Vol.26 No.1

This paper study on soil properties and earth pressure at the domestic multi layer. Reliable predictions of the movement of earth retaining structures and the ground adjacent to the braced walls in urban excavation are often difficult due to many variable factors. Also, Unpredictable behavior of ground and retaining structure due to variation of the above factors may cause considerable damage to the adjacent structures, and cost many of human lives as a results of retaining wall failure. The earth pressure at the retaining walls was measured at total 13 numbers sites and Peck's empirical earth pressures adapted at the design stage. The geotechnical properties by this research was proposed as a preliminary design guide line in urban excavation where controling ground movement and safety assurance of adjacent structure. The earth pressure of rock masses were found to be 70.14% of Peck's earth pressure and the earth pressure of soil were found to be 44.4% of Peck's earth pressure. It is indicated that the design earth pressures of a retaining wall is

대심도 탄성파 토모그래피 탐사를 이용한 암반분류

구자갑,김영덕,권소진 한국지반환경공학회 2002 한국지반환경공학회논문집 Vol.3 No.3

In tunnel design, geotechnical survey of over 200m tunnel depth is required because of its characteristical topography. For this reason, there are difficulties in collecting information of basic data in tunnel design because of large-scale costs in borehole tests, of limits to a geotechnical analysis by the existing refraction seismic survey and of analytical errors in steep mountainous area. Seismic tomography has many advantages as follows; 1) seismic velocity as absolute value is more reliable than electrical resistivity, 2) geotechnical analysis in deep tunnel depth is available by seismic velocity, 3) analytical errors is reduced in steep mountainous area. In this paper, it was found out a correlation of seismic velocity and Q in tunnel design in the neighborhood of the National Capital region and the reduction effect of tunnel construction cost using reliable rock quality by seismic tomography compared with by borehole data and electricity resistivity data. 본 연구에서는 수도권 근처의 터널설계시 대심도 탄성파 토모그래피 탐사에 의한 탄성파 속도와 Q 값과의 상관관계를 도출하고 이를 통한 정확한 암반분류로 공사비 절감효과에 대하여 고찰하였다. 터널전구간 지표면에서 탐사를 수행하여 대심도 구간의 자료를 얻어 암반분류를 수행하였으며, 이상대 구간에서는 VSP를 통한 자료를 추가하여 보다 상세한 자료를 얻어 신뢰성 향상을 얻을 수 있었다.

SCW, SCF의 일축압축강도에 대한 분석

구자갑,유범식 안성산업대학교 1998 論文集 Vol.30 No.2

This paper is to analyze the characteristics of the unconfined compression strength for improved soils. The improved soils has been selected by the laboratory mixing and the field mixing. The following conclusions are made by performing the experiments for the soil-cement wall (SCW) and the soil-cement foundation (SCF). The strength of improved soils are affected by various factors; moreover, reasonable design standards are not still available. Thus, the suitable mixing ratio should be determined to obtain the specified strength for construction sites. The relationship between the unconfined compressive strength and the aging of the improved soils may be the following equation; q_(u60) = (1.1~1.4)q_(u28) = (1.4~2.2)q_(u7) It has been found that the more long-term strength increases, the more improved materials are put in the sample soils. The confined compressive strength may be used as 7.5 kg/㎠ for the SCW and 18 kg/㎠ for SCF, respectively. Since the strength of improved soils are affected by various factors in construction sites, the field core tests and the field loading tests would be required to assure the results of this study in the project site.

준설매립점토의 침강 및 자중압밀 특성

구자갑 한경대학교 2003 論文集 Vol.35 No.-

Consideration of the assumptions made in Terzaghi’s theory of consolidation indicates that a main source of error is the assumed linear behavior of the soil. There are a number of consistently observed experimental facts which do not conform with the Terzaghi theory and which indicate that the basic model is in many cases oversimplified. In this paper, I studied experimentally on depositional properties of dredged soft clay by using Column tester, which are produced specially to self-weight consolidation experiment. The experiments of dredged materials are performed by two methods, one is to pour the specimen of dredged clay instantly and the other is to do by dividing in some steps. I will study the problems of increasement of shear strength in the soft clay ground during self-weight consolidation and long term settlement, and also find the solution which is considered the effect of secondary consolidation and creep.

설계기준 및 해석방법 연구

구자갑(Koo Jakap),박선규(Park Sunkyu),김상환(Kim Sanghwan),김병호(Kim Byungho),황제돈(Hwang Jedon),한녹희(Han Nokhui) 한국콘크리트학회 2004 한국콘크리트학회 학술대회 논문집 Vol.2004 No.5

지반공학적 특성파악을 위한 개별요소법의 적용성

구자갑(Koo Ja-Kap),전제성(Jeon Je-Sung) 대한토목학회 2007 대한토목학회논문집 C Vol.27 No.1

본 연구에서는 조립재료에 대한 대형 및 소형 삼축압축시험 결과를 이용하여, 개별요소방법에 의한 모델링을 수행하였다. 또한 개별요소해석시, 초기 간극률 조건 및 상사입도 조정에 대한 응력-변형 거동특성과 그에 따른 개별요소방법의 적용성을 살펴보았고, 본딩효과가 없는 경우의 접촉면 구성모델에 사용되는 미시 물성치들이 전체적인 거동 및 강도에 미치는 영향을 분석하였다. 그 결과, 개별요소방법은 실내시험결괴를 현장 스케일의 대상으로 확장하는데 있어 매우 유용한 지반공학적 접근방법임을 확인할 수 있었으며, calibration 과정을 통한 미시 물성치(micro parameter)를 산정결과를 이용하여 다양한 응력 조건 및 하중재하조건에 대한 응용해석 수행이 가능함을 알 수 있었다. In this research, numerical simulations using distinct element method have been conducted with laboratory tests including triaxial tests for coarse grained materials. For simulations of distinct element method, modeling of grain size distribution from 0.1 ㎜n to 50㎜ has been conducted by clump logic. The effects of initial porosity (n<SUB>o</SUB>=0.11, 0.14, 0.17, 0.20), up-scaling (SR= 1.0, 5.0, 10.0, 20.0) for particle size and micro parameters such as ball stiffness, stiffness ration and friction coefficient have been investigated to confirm the applicability of this method to geotechnical problems. These numerical results show that distinct particle modelling should be a valuable method to predict geotechnical considerations of in-situ condition from laboratory test results. With micro parameters which are chosen by calibration process, discrete particle modelling of triaxial tests in case of other confining stress and cyclic loading condition were available.