• Geomechanics and Engineering
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• 제21권3호
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• pp.269-277
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• 2020

In this study, numerical analyses were conducted to investigate the load transfer mechanisms and dynamic responses between the vertical shaft and the surrounding soil using a dynamic analysis method and a pseudo-static method (called response displacement method, RDM). Numerical solutions were verified against data from the literature. A series of parametric studies was performed with three different transient motions and various surrounding soils. The results showed that the soil stratigraphy and excitation motions significantly influenced the dynamic behavior of the vertical shaft. Maximum values of the shear force and bending moment occurred near an interface between the soil layers. In addition, deformations and load distributions of the vertical shaft were highly influenced by the amplified seismic waves on the vertical shaft constructed in multi-layered soils. Throughout the comparison results between the dynamic analysis method and the RDM, the results from the dynamic analyses showed good agreement with those from the RDM calculated by a double-cosine method.

• 한국지반공학회논문집
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• 제32권6호
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• pp.17-26
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• 2016

지반의 동결-융해 과정에 의한 지반구조물의 거동 특성을 이해하기 위해서는 동결에 의한 지반의 상변화와 구조물과의 상호작용에 대한 연구가 필요하다. 본 연구에서는 기존의 동상 팽창 실험결과에 대한 역해석을 수행하여 얼음포화도에 따란 탄성계수 모델식을 제시하였다. 실트지반은 화강풍화토와 모래지반에 비하여 탄성계수가 얼음포화도에 대하여 매우 민감하고, 화강풍화토는 실트에 비하여 초기 포화도가 탄성계수에 미치는 영향이 큰 것으로 나타났다. 매설 냉각가스관에 대한 수치해석은 가스관 주변의 연중 동결 영역이 외부 동결하중에 대하여 shield 역할을 하여 추가적인 외력의 영향은 상대적으로 작은 것으로 나타났다. 그리고 모래로 치환된 지반에 설치된 가스관은 주변 원지반(화강풍화토)과 치환 모래의 상대적인 탄성계수의 차이로 히빙량이 크게 나타나지만, 외부하중을 효과적으로 재분배하여 안정적인 응력상태에 도달함을 알 수 있다.

• 한국토양비료학회지
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• 제48권5호
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• pp.442-450
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• 2015

This study was conducted to investigate the effect of Psy-2A-CrtI (PAC), a genetically modified (GM) rice with enhanced ${\beta}$-carotene, on the soil microbial community. The soil used to cultivate GM rice and its wild-type, Nakdong, was analyzed for population density, denaturing gradient gel electrophoresis (DGGE), and pyrosequencing. It was found that the bacterial, fungal and actinomycetes population densities of the PAC soils were within the range of those of the non-GM rice cultivar, Nakdong. The DGGE banding patterns of the GM and non-GM soils were also similar, suggesting that the bacterial community structures were stable within a given month and were unaffected by the presence of a GM plant. The pyrosequencing result showed a temporal difference in microorganism taxon and distribution ratio, but no significant difference between GM and non-GM was found. The persistence of the transgene DNA in the plant and surrounding soil were investigated for different time periods. There were differences in the persistence within the plant depending on the gene, but they could not be detected after 5 weeks. Also the transgenes were not detected in the surrounding soil. These results indicate that soil microbial communities are unaffected by the cultivation of a PAC rice within the experimental time frame.

• 대한토목학회논문집
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• 제30권6C호
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• pp.241-253
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• 2010

본 연구에서는 응답변위법을 수직구 내진설계에 적용하고 구조물의 응답을 정확하게 구할 수 있는 방법을 제시하고자 기반면, 지반의 상대변위 산정 방법, 하중 산정 및 적용 방법에 따른 3차원 유한요소해석을 수행하였다. 그 결과, 수직구 내진설계를 위한 기반면은 전단파속도가 1500m/s를 초과하는 지반을 선정하는 것이 가장 적합하며, 지반변위 산정 방법은 다층지반의 특성을 반영할 수 있는 double cosine이 가장 적합하다. 또한 응답변위법 해석을 위한 동토압 및 주면전단력 산정 시 구조물의 단면형상효과를 고려하는 것이 실제 수직구의 동적거동을 적절히 반영하며 경제적인 설계를 할 수 있음을 알 수 있었다.

• 한국지하수토양환경학회지:지하수토양환경
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• 제15권3호
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• pp.52-60
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• 2010

The stone-dust is an unavoidable by-product of aggregate production, which is produced about 0.8~1.0 million $m^3$ annually. The stone-dust is currently regarded as a hazard material on environment because it is classified as an industrial waste in the Waste Management Law of Korea. At present, the stone-dust is considered as a environmentally hazardous material, and is classified as an industrial waste according to the Waste Management Law of Korea. In this study, we assessed the heavy-metal contamination of the stone-dust on surrounding environments by various leaching tests. Leaching experiments (such as Korea Standard Leaching Procedure (KSLP), Soil Environment Preservation Act of Korea (SEPAK), Toxicity Characteristic Leaching Procedure (TCLP), and Synthetic Precipitation Leaching Procedure (SPLP)) show that very low heavy metals (As, Cd, Cu, Pb, Zn, Hg) and CN are leached out, or much less than each regulatory thresholds. The resuts of the leaching test with time in acidic solution (initial pH 5 and 3) indicate that pH-buffering minerals are present in the stone-dust. These results suggest that the stone-dust can not potentially affect adverse impact on surrounding environments such as surface water, groundwater and soil etc..

• Structural Engineering and Mechanics
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• 제13권5호
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• pp.543-556
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• 2002

A dynamic elastic local buckling analysis is presented for a pile subjected to an axial impact load. The pile is assumed to be geometrically perfect. The interactions between the pile and the surrounding soil are taken into account. The interactions include the normal pressure and skin friction on the surface of the pile due to the resistance of the soil. The analysis also includes the influence of the propagation of stress waves through the length of the pile to the distance at which buckling is initiated and the mass of the pile. A perturbation technique is used to determine the critical buckling length and the associated critical time. As a special case, the explicit expression for the buckling length of a pile is obtained without considering soil resistance and compared with the one obtained for a column by means of an alternative method. Numerical results obtained show good agreement with the experimental results. The effects of the normal pressure and the skin friction due to the surrounding soil, self-weight, stiffness and geometric dimension of the cross section on the critical buckling length are discussed. The sudden change of buckling modes is further considered to show the 'snap-through' phenomenon occurring as a result of stress wave propagation.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2003년도 봄 학술발표회 논문집
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• pp.821-826
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• 2003

Laboratory experiments were peformed to understand physical properties of soil-cement column under the influence of acidic flow including metal contaminants and its retaining capacity against metal migration. The contaminant used in this study was nitric acid with Cu and Cd. The Permeability of soil-cement column decreased when pH of the column began to drop below 12. Decreases in pH led to significant reduction of compressive strength of clayey soil-cement specimen, while relatively marginal reduction for sandy soil-cement specimen. The metal contaminants did not leachate from soil-cement column until pH of soil-cement dropped below 7∼8 for Cu and 9∼10 for Cd. Metal contaminants were precipitated and trapped inside the soil-cement column at pHs higher than those mentioned as verified with metal analysis and visual inspection. This indicated that soil-cement column not only performs well as a cut-off wall, but also helps alleviating the level of contamination of the surrounding environment.

• Geomechanics and Engineering
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• 제16권4호
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• pp.341-353
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• 2018

A reinforced concrete pedestrian tunnel is constructed under a four-track surface railway. Heavy rainfall and soil exposure to drying lead to soil with different water content throughout the year. A railway is an open utility that is subject to rainfall without control on the quantity of the water on it and when there is a tunnel under a railway, the water content of the soil around the tunnel is very influential. This research shows the effects of change of water content in the soil around a pedestrian tunnel under a four-track surface railway. The pedestrian tunnel and the soil block around the tunnel are modeled in 3D by the FEM and are studied under the vibrations induced by the moving trains on the four-track surface railway for different soil water contents and the effects of the soil water content on the dynamic behavior of the tunnel and the surrounding soil are demonstrated.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2000년도 가을 학술발표회논문집(I)
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• pp.87-92
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• 2000

The real situation of an underground reinforced concrete(RC) structure with the surrounding soil medium subjected to seismic load is quite difficult to be simulated through an expensive work and, even if it is possible to arrange such an experiment, it will be too expensive. So development of analytical method can be applied usefully to seismic design and seismic retrofit through an analysis of seismic behavior and seismic performance evaluation. A path-dependent constitutive model for soil that can estimate the response of soil layer is indispensible for dealing with kinematic interaction of RC/soil entire system under seismic loads. And interface model which deals with the dynamic interaction of RC/soil entire system is also necessary. In this study, finite element analysis program that can consider path-dependent behavior of RC and soil, and interfacial behavior between RC and soil is developed for rational seismic analysis of RC/soil entire system. Using this program, nonlinear behavior of interface between RC and soil is analyzed, and the effect of interfacial behavior to entire system is investigated.

• 한국안전학회지
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• 제20권1호
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• pp.101-106
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• 2005

When a underground structure is constructed at the site composed of soft soil, the behavior of a underground structure Is much affected by the motion of soft soil. Therefore, the effect of soil-structure interaction is an important consideration in the design of a underground structure such as tunnel at the site composed of soft soil. This paper presents the results of the study on dynamic response of tunnel structures and soil-structure interaction effects. The computer program SASSI was used in seismic analysis of tunnel structures because it is more capable of analyzing dynamic response or structures considering soil-structure interaction. As regards the results, the flexibility of surrounding soil affects dynamic response characteristics of tunnel structures and response of tunnel structures can be amplified.