• Earthquakes and Structures
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• 제15권2호
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• pp.193-202
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• 2018

This paper studied the probability of pounding occurred between decks and abutments of a long span high-pier continuous rigid fame bridge subjected to ground motions with local soil effect. A pounding probability analysis methodology has been proposed using peak acceleration at bedrock as intensity measure (IM) for multi-support seismic analysis. The bridge nonlinear finite element (FE) models was built with four different separation distances. Effect of actual site condition and non-uniform spatial soil profiles on seismic wave propagating from bedrock to ground surface is modelled. Pounding probability of the high-pier bridge under multi-support seismic excitations (MSSE) is analyzed based on the nonlinear incremental dynamic analysis (n-IDA). Pounding probability results under uniform excitations (UE) without actual local site effect are compared with that under MSSE with site effect. The study indicates that the required design separation length between deck and abutment under uniform excitations is larger than that under MSSE as the peak acceleration at bedrock increases. As the increase of both separation distance between deck and abutment and the peak acceleration, the probability of pounding occurred at a single abutment or at two abutments simultaneously under MSSE is less than that under UE. It is of great significance considering actual local site effect for determining the separation distance between deck and abutment through the probability pounding analysis of the high-pier bridge under MSSE.

• 콘크리트학회논문집
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• 제27권4호
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• pp.419-426
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• 2015

본 연구는 지하식 LNG 저장탱크의 시공에 앞서 연약지반의 개량을 위하여 현장 원위치의 흙과 시멘트, 벤토나이트 등을 사용하는 소일-시멘트 연속벽체를 효과적으로 시공하는 SMW 공법에 대한 배합설계 및 현장적용 사례를 실험적으로 규명하기 위한 것이다. 현장조건을 고려하여, 보통 포틀랜드 시멘트와 벤토나이트를 주재료로 선정하였고, 흙의 단위용적중량은 $1,833kg/m^3$을 적용하였으며, 이에 따른 물-시멘트비 4종류와 배합속도 3수준을 대상으로 블리딩 및 압축강도 실험을 실시하였다. 실험은 실내실험 및 현장적용 사례로 나누어 수행되었으며, 실험을 통하여 얻은 결론은 다음과 같다. (1) 물-시멘트비가 감소할수록, 배합속도(rpm)이 증가할수록, 블리딩량 및 블리딩율이 감소하는 것으로 나타났다. (2) 물-시멘트비 150% 이하에서 현장적용강도(1.5 MPa)를 만족하였으며, 현장 코아강도는 공시체 강도에 비해 8~23% 증가하였다. 따라서 적용현장 조건을 고려하여 단위시멘트량 $280kg/m^3$, 벤토나이트 $10kg/m^3$, 물-시멘트비 150%, 그리고 배합속도 90 rpm을 현장시공의 최적배합으로 제안하였으며, 현장적용 사례의 실험결과로부터 요구되는 성능을 만족하였다.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2005년도 학술발표회 논문집
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• pp.121-128
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• 2005

In this study the influences of ground motion characteristics and structural properties on energy demands were evaluated using 100 earthquake ground motions recorded in different soil conditions, and the results were compared with those of previous works. Results show that ductility ratios and the site conditions have significant influence on input energy. The ratio of hysteretic to input energy is considerably influenced by the ductility ratio and damping ratio, while site condition has minor effects.

• 기술사
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• 제38권5호
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• pp.5-9
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• 2005

The seismic design provisions of the 2005 KBC has been based on the 2000 IBC and has considered the building code situations in Korea. There are site ground motion, soil class, seismic design category in the significant changes of the 2005 KBC. In the case of soft soil condition, the response spectrum acceleration of the 2005 KBC is larger than that of previous code. To reduce the seismic force of the 2005 KBC, it need to introduce the eqrthauke force resisting system with high ductility.

• International Journal of Railway
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• 제6권2호
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• pp.45-52
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• 2013

Railway construction needs vast soil investigation for its infrastructure foundation designs along the planned railway path to identify the design parameters for stability and serviceability checks. The soil investigation data are usually classified and grouped to decide design input parameters per each construction section and budget estimates. Deterministic design method which most civil engineer and practitioner are familiar with has a clear limitation in construction/maintenance budget control, and occasionally produced overdesigned or unsafe design problems. Instead of using a batch type analysis with predetermined input parameters, data population collected from site soil investigation and design load condition can be statistically estimated for the mean and variance to present the feature of data distribution and optimized with a best fitting probability function. Probabilistic approach using entire feature of design input data enables to predict the worst, best and most probable cases based on identified ranges of soil and load data, which will help railway designer select construction method to save the time and cost. This paper introduces two Monte Carlo simulations actually applied on estimation of retaining wall external stability and long term settlement of organic soil in soil investigation area for a recent high speed railway project.

• 청정기술
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• 제8권2호
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• pp.67-76
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• 2002

Dewatered sludge of 400,000t/y from water treatment plants in Korea is being disposed through landfill and ocean dumping. However, the disposal is posing more and more serious environmental problems at the same time not only because of landfill site shortage in municipal suburbs, but because of the concern it will contaminate the oceans. In this study, the research on utilizing the sludge dried by flash dryer as covering soil in the landfill sites was carried out to solve these problems on environmental affinity. Both dewatered and dried sludge were exposed to the natural condition and observed according to the atmospheric changes. An experiment of soil engineering characteristics of the dried sludge and tests on mixed sludge(silty sandy soil : dried sludge = 10:90 ~ 30:70) such as particle size distribution, liquid and plastic limit, moisture content, specific gravity and compaction test were carried out. According to the compaction test, the compaction was confirmed as the optimum water content ratio was observed in the condition of SM-silty sand of particle size distribution, NP of liquid and plastic limit, 101.4% of moisture content, 2.04~2.12 of specific gravity. The results showed that dried sludges mixed with at least 30% of natural soil could be used as daily covering soil in the landfill sites.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2006년도 춘계 학술발표회 논문집
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• pp.1024-1031
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• 2006

In this study using the finite different programs, FLAC2D to define affection of the soil-structure interface in evaluating the behavior of adjacent structures according to excavation, and tried to compare each the results of different 46 cases which were various condition of stories, length and locations from the excavation site. In the result of the numerical analysis, the affection of the interface was affected by the building stories, locations from the excavation site and shape ratio(length/height). Therefore, in the considering soil-structure interaction in the damage assessment and the behavior of the adjacent structures when excavation, is important in more accurate evaluation of the movement of structure. Also, the interface modification factor were proposed which can consider the interface.

• 한국제4기학회지
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• 제18권2호통권23호
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• pp.33-42
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• 2004

In South Korea a Pedo-sedimentary Sequence(PS) indicating the Last Glacial Maximun(LGM) is typified y a brown to dark brown, relatively stiff paleosol layers formed by repetitive freezing and thawing processes which in turn left characteristi glossic textures in soil-solum, polygolnal structures with a flagipans, vertical soil wedges or freezing cracks, and horizontal foliations, As a pre-LGM sedimentary sequences (older than 25Ka), the Old Fluvial Sequence(OFS) overlain by the Slope Sedimentary Sequence(SS) are distributed commonly at the base level higher than 14-15m above present river-bed along the major river basin. After the LGM (ca. 18Ka), the Young Fluvial Sequence(YFS) appears at an altitude ascending order of sedimentary profiles. In this fluvial organic muds of Jangheungri site(Jinju), Sorori site(Cheonwon), and Youngsan estruarine rivermouth(Mokpo) were exemplified in order to interpret their formation ages and environments. As result of $^{14}C$ datings, the formation ages of te organic muds are Boelling to Alleroed (MIS-1). These organic muds were fomed in fluvial backswamp or local pond/bog in response to shifting fluvial system. On the basis of palynological production dominant with Abies/Picea-Betula and Ranunculaceae, Compositae, Cyperaceae, and Graminae, it was interpreted that more boreal to subboreal condition was prevailed rather than temperate like today during the formation of organic muds and soil moisture condition was a repetition of wet and dry condition.

• 한국환경복원기술학회지
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• 제17권5호
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• pp.79-89
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• 2014

This study was carried out to provide basic information to improve the surrounding ecosystems with benefit analysis and monitoring in cut slopes following establishment of a test construction to improve ecological environment in slopes of an expressway. Field tests from October 2012 to May 2013 were conducted in Seosejong IC and Shinyang IC. In order to improve the view of slopes, soil condition is an important factor. The earth slope, it is possible to introduce directly the plant. Stable construction method was applied, another foundation for planting is necessary. The mixing ratio of the seeds according to the experimental results, the difference was found at an early stage plants in Site I (Seosejong IC). Trees were planted on terraced structures were well coordinated and pictures. The growth of planted trees was good in Site II (Shinyang IC). Due to the use of plants in the landscape will continue to change. Thus, long-term monitoring and landscape analysis will be needed.

• 한국산학기술학회논문지
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• 제12권11호
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• pp.5306-5313
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• 2011

기존 동조질량감쇠기의 최적설계변수에 관한 연구는 풍하중과 같은 조화하중을 받는 구조물을 대상으로 연구가 수행되었다. 본 연구에서는 수치해석을 통하여 지진하중이 작용하는 건축물에 설치되는 동조질량감쇠기의 최적 감쇠비와 동조진동수비를 구하였다. 지반특성을 단단한 지반, 연약지반, 단층 근처 지반으로 분류하고, 이들 지반특성을 고려한 수치해석을 통해 구한 동조질량감쇠기의 설계변수를 기존 연구 결과와 비교하였다. 수치해석결과 본 연구로부터 구해진 동조질량감쇠기의 설계변수값을 적용한 경우 지진하중에 의한 응답제어에 기존 연구를 통해 얻어진 변수값을 적용한 경우에 비해 더 나은 제어효과를 얻을 수 있음을 알 수 있었다.