• 한국안전학회지
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• 제23권2호
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• pp.7-13
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• 2008

In a long-span bridge which is constructed on soft soil, it is requested to make a plan considering soil-structure interaction, and soil-structure interaction is partially under consideration at the actual bridge plan. Many researches on dynamic behavior of a bridge affected by soil-structure interacting have been accomplished, but it is difficult to estimate dynamic behavior of a bridge on soft soil accurately because of many uncertainties. This paper presents the results about dynamic response of a long-span suspension bridge in the site composed of soft soil considering incident angle of input ground motion. The effect of soft soil was evaluated by the use o computer program SASSI and a long-span suspension bridge was modeled by finite element program MIDAS. The effect of incident angle of input ground motion was investigated on the dynamic response of a long-span bridge.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 추계학술대회 논문집
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• pp.918-927
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• 2008

The problems associated with constructing high-speed concrete track embankments over soft compressible soil has lead to the development and/or extensive use of many of the ground improvement techniques used today. Drains, surcharge loading, and geosynthetic reinforcement, have all been used to solve the settlement and embankment stability issues associated with construction on soft soils. Geosynthetic-reinforced embankment supporting piles method consist of vertical columns that are designed to transfer the load of the embankment through the soft compressible soil layer to a firm foundation and one or more layers of geosynthetic reinforcement placed between the top of the columns and the bottom of the embankment. In the paper, the evaluations of a seismic performance of geosynthetic-reinforced embankment piles for a ultra soft ground during earthquake were studied. the equivalent linear analysis was performed by SHAKE for soft ground. A seismic performance analysis of Piles was performed by GROUP PILE and PLAXIS for geosynthetic-reinforced embankment piles. Guidelines is required for pile displacement during earthquake. Conclusions of the studies come up with a idea for soil stiffness, conditions of pile cap, pile length and span.

• 한국지반공학회논문집
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• 제20권2호
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• pp.59-66
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• 2004

SCP 개량지반은 연약지반에 타설된 모래말뚝과 주변 연약지반으로 구성된 복합지반을 형성한다. 복합지반에 상재하중이 작용할 경우, SCP쪽으로 반경방향의 흐름에 의하여 시간의존적인 압밀거동이 유발될 뿐만 아니라, SCP와 주변 연약지반 사이에서 강성도 차이로 인하여 응력전이가 유발된다. 본 논문은 SCP 개량지반의 압밀거동에 대한 교란효과의 영향을 고려하기 위하여 원통형 실린더 지반에 대한 수치해석을 수행하였다. 수치해석결과 연약지반의 교란영역은 유효응력-간극수압의 거동, 응력전이기구, 응력분담비에 영향을 줌을 알 수 있었다. 또한 SCP와 점토 사이의 응력전이량은 상부 z/H=0.25에서 가장 크며, 깊이가 증가함에 따라 감소한다. 응력분담비는 상수값이 아니라 압밀과정에 의존하며, 교란영역을 가진 연약지반의 응력분담비는 교란영역이 없는 연약지반의 응력분담비보다 큼을 알 수 있다.

• 한국지반환경공학회 논문집
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• 제7권5호
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• pp.5-11
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• 2006

연약지반 설계시 영향을 미치는 주요 요인으로는 연약지반의 심도 및 지반의 특성값(압축지수, 압밀계수)을 결정하는 것이다. 이것은 연약지반의 설계시 지반의 침하거동을 예측할 수 있는 기초 자료가 된다. 신뢰성이 높은 지반조사 장비로 연약층의 심도를 결정하였더라도, 연약지반의 역학적 특성을 찾기 위한 실내시험 조건이 실제 지반환경을 완벽하게 재현하지 못하기 때문에 정확한 지반 특성값을 결정하는 것은 상당히 어려운 것이 현실이다. 따라서, 본 연구에서는 가장 신뢰성 있는 지반 특성값을 재산정하기 위해 인천국제공항 2단계 여객계류장 부지조성시의 317일간의 현장 계측데이터를 역해석 기법을 이용하여 지반의 특성값을 재산정하였다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 추계 학술발표회 2차
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• pp.152-160
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• 2010

In this study, cohesion of soft ground, soft ground depth and embankment height varying conditions, such as the impact of each condition after the calculation of the range, SCP was performed to evaluate the applicability of the method. Reinforcing effects of scope, and permit lateral movement of SCP 2D and 3D analysis of the program were calculated by the displacement ratio, the result follows. The height and depth of soft soil embankment with increasing and decreasing the cohesion tends to be affected were long range, SCP method applied by the finite element analysis Cu = 1.0tf/$m^2$, embankment height is 3.0m depth of soft soil can be applied in a less than 5.0m, and Cu = 3.0tf/$m^2$, embankment height, the soft soil depth is 3.0m 12.0m, Cu = 3.0tf/$m^2$, embankment height is 5.0m less than 7.0m depth of soft soil can be applied in was. And Cu = 5.0tf/$m^2$, embankment height is 3.0m below 15.0m depth rouge anti Floor, Cu = 3.0tf/$m^2$, embankment height of 5.0m 12.0m depth below the soft soil, Cu = 5.0tf/$m^2$, If the depth of soft soil embankment height of 7.0m and below 5.0m was applicable.

• 한국터널지하공간학회 논문집
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• 제2권3호
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• pp.71-81
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• 2000

NATM 터널을 시공함에 있어서 정확한 지반조사 결과에 의한 설계가 요구되나, 현실적으로 완벽하게 지반조건을 파악하지 못하고 설계가 진행되는 경우가 많다. 특히 연약지반 또는 지하수의 유입이 급격히 진행되는 등의 열악한 지반과 조우하였을 때에는 현황을 최적으로 반영할 수 있는 계측결과에 기준한 적절한 보강공사 등의 터널의 안정성 확보가 요구된다. 본 보고서에서는 토사 터널 구간의 시공에 있어서, 발생한 변위량을 재현할 수 있도록 터널 계측결과를 이용한 역해석 (back analysis)을 통해 지반의 공학적 제상수를 재평가 한 후, 유한차분법을 이용한 수치해석을 이용하여 최적의 터널 안정성을 검토하였다. 또한 수치해석 결과 및 시공 현황 등을 고려하여 터널 측벽 및 하반부에 강관 일단식 그라우팅과 상반 굴착 후에 가인버트 공법 등을 적용하여 터널의 역학적 안정성을 확보한 토사구간의 굴착을 완료하였다.

• 산업기술연구
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• 제26권A호
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• pp.101-108
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• 2006

This study is the results of experimental and numerical study on the consolidational behavior of multi-layered soft soil ground installed with plastic board drains (PBD). Centrifuge model tests with a marine clay sampled from field were performed to investigate the consolidational behavior of multi-layered ground where a dredged soil was placed on the soft clay ground and PBDs were installed. Test results were compared with those of numerical analyses, using the 2-D equivalent model previously proposed. From test results, it was found that the amount of consolidation settlement occurred in the original ground due to embankment surcharge loads was in the range of 38% of total settlement in the whole ground. From the results of cone penetration tests executed after finishing the centrifuge model tests, the cone resistance was found to increase with depth. The measured water contents inbetween PBDs were in the ranges of 38~50% and their values tended to increase with increasing the distance between PBDs.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2000년도 토목섬유 특별세미나
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• pp.61-69
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• 2000

It is not easy to find a good soil condition due to the shortage of suitable land for construction work. The earth structure and buildings can be constructed over the soft soil. The soft soil must be treated either using the reinforcement element or dewatering. Most of land reclamation projects are being implemented along the south coast or west coast of the Korean Peninsula. The soils in these areas are covered with the soft marine clay, so soil and site improvement is the most important things to do. Pile foundation at the bottom of embankment can be constructed either in the soft ground or in the soil contaminated area. The purpose of this research is to develop "geogrid-reinforced piled embankment method" to prevent the differential settlement and increase the bearing capacity of soil. In this study, the effectiveness of the geogrid-reinforcement was studied by varying the space between piles and reinforcement conditions. Also, the geotechnical engineering properties of the embankment material and foundation soil were determined through the laboratory tests as well as the field tests. As a result, the site that the pile-spacing S = 3b with geogrid reinforcement is the most effective to reduce the differential settlement and increase load bearing capacity.

• 한국지반환경공학회 논문집
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• 제13권12호
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• pp.35-42
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• 2012

연약지반에 구조물을 설치하거나 도로 또는 단지를 조성하는 경우 지지력 부족으로 인한 지반 전단파괴 및 과도한 압밀침하 등 공학적 문제가 발생하게 되어, 강도증가 및 침하억제를 위한 지반 개량공사를 필수적으로 시행하여야 한다. 연약지반을 개량함에 있어 현장계측자료를 바탕으로 한 장기침하량 예측은 선행재하 성토고 및 압밀완료시점 예측을 위한 매우 중요한 요소로 이에 관한 연구가 국내 외 여러 학자들에 의해 진행되고 있다. 본 연구에서는 선행재하 및 연직배수 공법을 적용하여 점성토 연약지반개량을 시행한 연구 대상 지역의 압밀침하 특성을 분석하였으며, 쌍곡선법, ${\sqrt{S}}$법, Asaoka법을 적용하여 압밀도에 따른 예측 침하량과 실측 최종침하량을 비교 분석하여 김포한강지구의 토질특성에 맞는 침하예측기법을 연구하였다. 연구결과에 의하면 3가지 예측방법으로 추정한 침하량과 계측침하량의 오차가 최대 ${\pm}4$% 이내로 실 침하량과 거의 일치하였으며, 예측의 정확도는 Asaoka법, 쌍곡선법, ${\sqrt{s}}$법 순으로 나타났다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 추계 학술발표회
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• pp.336-345
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• 2010

GS E&C was awarded the contract for the construction of Hanoi - Hai Phong Expressway Package EX-7 from Station Km 72+000 to Station Km 81+300 in December 2008. This project is the $7^{th}$ contract package of the 105.5 km long expressway near Hai Phong city, which includes a FCM-styled bridge along with high embankments over soft ground. For these high embankments, there is a need to treat the soft soil for improving the overall stability during construction and for reducing the post-construction settlement of the expressway. The Designer of this project had adopted four (4) different types of ground improvement techniques to treat the soft ground, including the prefabricated vertical drains (PVD), sand drains (SD), pack drains (PD, or sometimes called packed sand drains), and sand compaction piles (SCP). The main focus of soft soil treatment should be paid attention to the residual settlement after construction. In current design, however, it appeared that the secondary compression (or creep) of the improved soil layer and the consolidation settlement of the lower untreated compressible soil layer have been neglected in the estimation of the post-construction settlement. These uncalculated residual settlements may not only unsatisfy the design criteria but also raise serious problems during service period of this expressway. In this paper, the subsoil condition and current design were reviewed focusing on the employed soft soil treatment method and expected residual settlement.