• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2006년도 추계 학술발표회
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• pp.490-496
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• 2006

In order to design accurately plastic board drain (PBB) method, it is important to determine the equivalent circle of PBD. In this paper, a series of numerical analyses on soft ground improved by PBD were carried out, in order to investigate the resonable equivalent circle of PBD considering consolidation behavior of improved soft ground by PBD. The applicability of numerical analyses, in which an elasto-viscoplastic three-dimensional consolidation finite element method was applied, could be confirmed comparing with results of a series of model tests on consolidation behaviors of soft ground improved by PBD. And, through the results of the numerical analyses, consolidation behaviors of soft ground during consolidation was elucidated, together with the equivalent circle of PBD considering consolidation behaviors.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2002년도 봄 학술발표회 논문집
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• pp.347-354
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• 2002

In this paper, when structures are constructed in the soft ground with poor bearing capacity at Incheon International Airport(railroad area), as for the grouting columns built In soft ground by high pressure jet grouting with Triple tube rod(super injection grouting), the effects on reinforcement and bearing capacity of ground are investigated. A unconfined compressive strength tests has been performed on the specimens sampled from the grouting columns and a mass plate bearing test has been performed on a grouting column. The test results show that super injection grouting has a sufficient effect on composite ground improved of foundation ground and reatraint of settlement of structure.

• 한국농공학회지
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• 제42권6호
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• pp.98-105
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• 2000

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$^{-3}$ cm/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.

• 한국지반신소재학회논문집
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• 제4권4호
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• pp.39-46
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• 2005

점성을 고려한 연약점토지반의 압밀거동을 파악하기 위해 플라스틱보드드레인(PBD)에 의해 개량된 연약점토지반의 압밀거동에 대한 탄점소성 3차원 수치해석을 실시하였다. 본 연구에서 사용한 수치해석기법의 적용성은 기존에 실시한 모형실험의 결과와 수치해석의 결과를 비교함으로써 검증하였다. 수치해석 결과로부터 연약점토지반의 침하 및 과잉간극수압의 소산거동, 유효응력증분의 변화 특성을 파악할 수 있었으며, 기존의 일차원 압밀해석 결과와의 비교를 통해 개량지반에서 발생하는 이차압밀특성을 평가하였다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2002년도 가을 학술발표회 논문집
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• pp.529-536
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• 2002

The purpose of this paper os to present and discuss some of flow and drain observed in modelling results. Because dredged fill ground of Yul-Chon located in the south coast of Korea is very soft, this ground should be improved after operation of surface stabilization. There are surface stabilization method such as chemical stabilization, desiccation, horizontally vacuum drain, replacement, and geosynthetics. In Yul-Chon, PTM(Progressive Trenching Method) is adopted to provide the necessity condition of surface desiccation. In the case trench in the dredged soft ground is formed by PTM equipment, pore water in the ground is drained through trench. There, drain and desiccation of surface ground increase, and bearing capacity is improved. In this research, when trench in the dredged soft ground is formed by PTM equipment, permeable characteristics and drain efficiency of pore-water are analyzed using SEEP/W software package. Results show variation of total head, pressure head, flux, hydraulic gradient, and flow quantity.

• 산업기술연구
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• 제22권B호
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• pp.211-218
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• 2002

The paper is to show the behavior of composit ground which is installed with sheet pile in soft soil improved by sand compaction pile. The results of load-settlement relationship, earth pressure, stress concentration characteristics, and final water content were obtained by centrifuge model test. Two cases of tests, installation of sheet pile on the corner and both side of the loading plate for the improved SCP ground which was designed twice of the footing width, were performed for the tests under the vertical and horizontal loading and both side of corner. Finite element program(CRISP) for sand compaction pile using elasto-plastic model and numerical analysis for soft soil using modified cam-clay constitutive equation were compared and analized with the results of model tests. The result of analysis show the increased bearing capacity of soil after, SCP and sheet pile was installed.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2002년도 추계 학술발표회 논문집
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• pp.114-122
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• 2002

The ASCE formula of lifeline.soil interaction force is the basis of semi-analytical relationship for buried pipelines subjected to longitudinal permanent ground deformation due to seismic induced liquefaction. However, since the ASCE formula has been developed based on the stiffness of non-liquefied region, it is needed to modify for the varied stiffness of liquefied region. With this object, the consideration of decreasing effect of soil stiffness in liquefied region is made: i.e. the spatial distributions of pipeline-soil interaction force in liquefied region. It means that the improved formula can reflect various patterns of permanent ground deformation more realistically. Through the comparative analyses using both the improved and ASCE formula, the applicability of the improved and the limitation of the ASCE formula and semi-analytical relationship are discussed. Also, relative influences of various parameters are evaluated for the clarification of behavior of pipeline subjected to longitudinal permanent ground deformation due to liquefaction.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2004년도 춘계학술발표회
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• pp.197-202
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• 2004

In order to design accurately sand compaction pile (SCP) method with low replacement area ratio, it is important to understand the mechanical interaction between sand piles and clays and its mechanism during consolidation process of the composition ground. In this paper, a series of numerical analyses on composition ground improved by SCP with low replacement area ratio were carried out, in order to investigate the mechanical interaction between sand piles and clays. The applicability of numerical analyses, in which an elasto-viscoplastic consolidation finite element method was applied, could be confirmed comparing with results of a series of model tests on consolidation behaviors of composition ground improved by SCP. And, through the results of the numerical analyses, each mechanical behaviors of sand piles and clays in the composition ground during consolidation was elucidated, together with stress sharing mechanism between sand piles and clays.

• 한국환경복원기술학회지
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• 제2권3호
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• pp.18-24
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• 1999

본 연구는 인공지반의 녹화에 보편적으로 이용되고 있는 자연토양, 개량토양, 인공토양에 따른 식물의 생육상태를 밝히기 위해 몇 가지 토양을 배합조성하고 이에 따른 목본식물(자산홍)의 생장상태를 측정하여 다음과 같은 결론을 얻었다. 먼저 토양종류에 따른 목본식물의 생장인자 간에 상관분석을 실시한 결과 지하부의 생장은 공극량 등이 중요하게 관여하고 있으며, 지상부의 경우는 전질소비가 생장에 중요한 영향요인으로 작용되고 있는 것으로 나타났다. 토양재료중 자연토양(밭흙)은 지상의 생장(수고, 엽수, 엽폭, 절화수)과 지상부의 건물중, 지하부의 건물중 모두 가장 저조한 것으로 나타났다. 인공토양(버미큘라이트)은 지상의 생장(수고, 엽수, 엽폭, 절화수 등)은 좋지 않았으나 상대적으로 지하부의 건물중이 월등히 높았으며 이러한 지하부의 우수한 생육에 기인하여 총건물중도 가장 높게 나타났다. 따라서 인공토양인 버미큘라이트의 경우 지닌 양분이 미약하여 지상의 생육상태는 양호하지 못했으나 통기성 및 투수성 등이 좋아 지하부의 생육에 결정적인 영향을 미친 것으로 판단된다. 밭흙을 주재료로 한 개량토양 중 버미큘라이트와 훈탄을 배합한 처리구는 지상부, 지하부 모두 중간정도의 생장상태를 나타냈다. 부숙톱밥을 혼합한 개량토양의 경우 총건물중은 인공토양(버미큘라이트) 다음으로 높았으며 나머지 수고, 엽수, 엽폭, 절화수 및 지상부의 건물중 등 지상부의 생장상태는 가장 좋은 것으로 나타났다. 특히 유기물 재료 중에서도 훈탄보다는 부숙톱밥이 들어간 배합토에서 생육이 좋은 것으로 나타났다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2005년도 춘계 학술발표회 논문집
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• pp.163-170
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• 2005

In this paper, the rock bolts, soil nails with filling grout and the micro-piling with injecting grout by pressure were applied for the stabilization of the cut slopes consisting of sedimentary rocks, igneous rocks and metamorphic rocks respectively. The field measurements and 3-D FEM analyses to find out mobilized tensile stresses of the grouted-reinforcing members installed in the drilled holes were executed on each site. With assuming the increments of the cohesive strength in the improved ground, the back analysis using direct calibration approach of changing the elastic modulus of the ground was used to find out the improved elastic modulus which yields the same tensile stresses from field measurements. The results of back analysis show that the elastic modulus of the improved ground were 4 to 6 times as large as the elastic modulus of original ground. Consequently, the design for slope reinforcement to be more rational, it is proposed that not only the improved cohesive strength is to be used in the incremental ranges on well-known previous proposed data, but also the increased elastic modulus which is about 5 times as large as the original elastic modulus is to be considered in design.