• 공학논문집
• /
• 제6권1호
• /
• pp.83-96
• /
• 2004

강판파일로 지지되고 있는 미니 교대하부에, 압성토의 제거에 따른 교대의 안정성을 확보하기 위한 방법으로서 쏘일네일링 공법을 채택하였다. 네일벽체에 각종 계측기를 매설하여 벽체의 거동을 추적하였다. 또한 3차원 유한요소해석기법을 이용하여 쏘일네일 벽체와 기존 구조물사이의 상호영향과 관련된 벽체의 거동을 분석하였다. 압성토의 순차적 제거와 네일타설 등의 전 축조 시퀀스를 모델링 할 수 있는 기법을 개발하였으며 개발된 시뮬레이션 기법의 타당성을 검증하기 위해 현장에 축조된 실물 계측데이터를 이용하여 보정하였고, 압성토의 제거와 네일타설이 기존 파일의 축하중 및 휨모멘트에 미치는 영향과 네일 인장력의 변화와의 상관관계 등, 설계시 고려되어야 할 몇 가지 주요한 사항에 대한 해석결과를 구할 수 있었다.

• Geomechanics and Engineering
• /
• 제16권3호
• /
• pp.309-320
• /
• 2018

In this paper, a numerical study using finite element method with considering soil-structure interaction was conducted to investigate the stress and deformation behavior of a sheet pile wall structure. In numerical model, one of the nonlinear elastic material constitutive models, Duncan-Chang E-v model, is used for describing soil behavior. The hard contact constitutive model is used for simulating the behavior of interface between the sheet pile wall and soil. The construction process of excavation and backfill is simulated by the way of step loading. We also compare the present numerical method with the in-situ test results for verifying the numerical methods. The numerical analysis showed that the soil excavation in the lock chamber has a huge effect on the wall deflection and stress, pile deflection, and anchor force. With the increase of distance between anchored bars, the maximum wall deflection and anchor force increase, while the maximum wall stress decreases. At a low elevation of anchored bar, the maximum wall bending moment decreases, but the maximum wall deflection, pile deflection, and anchor force both increase. The construction procedure with first excavation and then backfill is quite favorable for decreasing pile deflection, wall deflection and stress, and anchor forces.

• 한국지하수토양환경학회:학술대회논문집
• /
• 한국지하수토양환경학회 2006년도 총회 및 춘계학술발표회
• /
• pp.216-219
• /
• 2006

Water retention curve (WRC), one of soil hydraulic properties, is often approximated by property-transfer models (PTMs). Using the PTMs, we can estimate the WRCs from other physical properties such as particle-size distribution (PSD). The objective of this work was to investigate the performance of two PTMs with different origins for numerical simulations on transport of Benzo[a]pyrene in a soil. To do this, we chose both PTMs with different origins, i.e., (1) the lognormal distribution model (L anti NL models), and (2) the modified $Kov\'{a}cs$ model (MK model). The MK model showed tile worse performance in estimation of the WRCs. When transport of B[a]P was simulated, the MK model predicted to move farther than the L and NL models did, indicating that transport of B[a]P in a soil can be greatly influenced by the choice of PTMs.

• 한국방재안전학회논문집
• /
• 제10권1호
• /
• pp.47-53
• /
• 2017

지반 굴착에 따른 주변 지반의 함몰 문제를 예측하고 평가하기 위해서는 지반함몰 위험인자의 정확한 탐사가 필요하다. 이 연구에서는 지반굴착현장 주변의 거동 분석을 통하여 지반이완영역 분포를 분석하고 여러 가지 조건에서 GPR 탐사를 시뮬레이션 한 결과, 함수율에 따라 다소 차이는 있으나 불포화 지반에서는 지층의 분포 및 이완영역 분포를 확인할 수 있었으며, 포화 지반에서는 GPR 탐사의 어려움이 있는 것으로 나타났다.

• Weed & Turfgrass Science
• /
• 제5권2호
• /
• pp.88-94
• /
• 2016

Vehicular traffic on turf results in loss of green cover due to direct tearing of shoots and indirect long-term soil compaction. Protection of turfgrass crowns from wear could increase the ability of turf to recover from heavy traffic. Plastic turfpavers have been installed in trafficked areas to reduce soil compaction and to protect turfgrass crowns from wear. The objectives of this study were to evaluate traffic performance of turfgrasses (Zoysia matrella and Axonopus compressus) and soil mixture (high, medium and low sand mix) combinations on turf-paver complex. The traffic performance of turf and recovery was evaluated based on percent green cover determined by digital image analysis and spectral reflectance responses by NDVI-meter. Bulk density cores indicated significant increase in soil compaction from medium and low sand mixtures compared to high sand mixture. Higher reduction of percent green cover was observed from A. compressus (30-40%) than Z. matrella (10-20%) across soil mixtures. Both turf species displayed higher wear tolerance when established on higher sand (>50% sand) than low sand mixture. Positive turf recovery was also supported by complementary spectral responses. Establishment of Zoysia matrella turf on turfpaver complex using high sand mixture will result in improved wear tolerance.

• Earthquakes and Structures
• /
• 제7권1호
• /
• pp.83-99
• /
• 2014

This study is devoted to estimate higher-mode effects for multi-story structures with considering soil-structure interaction subjected to decomposed parts of near-fault ground motions. The soil beneath the super-structure is simulated based on the Cone model concept. Two-dimensional structural models of 5, 15, and 25-story shear buildings are idealized by using nonlinear stick models. The ratio of base shears for the soil-MDOF structure system to those obtained from the equivalent soil-SDOF structure system is selected as an estimator to quantify the higher-mode effects. The results demonstrate that the trend of higher-mode effects is regular for pulse component and has a descending variation with respect to the pulse period, whereas an erratic pattern is obtained for high-frequency component. Moreover, the effect of pulse component on higher modes is more significant than high-frequency part for very short-period pulses and as the pulse period increases this phenomenon becomes vice-versa. SSI mechanism increases the higher-mode effects for both pulse and high-frequency components and slenderizing the super-structure amplifies such effects. Furthermore, for low story ductility ranges, increasing nonlinearity level leads to intensify the higher-mode effects; however, for high story ductility, such effects mitigates.

• Geomechanics and Engineering
• /
• 제4권2호
• /
• pp.121-134
• /
• 2012

The paper presents the results of identification, monotonous and cyclic triaxial tests on a potentially liquefiable soil from the Guadeloupe island. The material is a very soft clayey soil whose susceptibility to liquefaction is not clear when referring to index properties such as grain size distribution, plasticity, etc. The classifications found in the literature indicate that the material has rather a "clay-like" behaviour, i.e., is not very susceptible to liquefaction, but its properties are very close to the threshold values given by the authors. Cyclic triaxial tests carried out on the material under different conditions show that liquefaction is possible for a relatively important level of cyclic deviator or number of cycles. The second part of the paper is devoted to the study of the recovery of the soil after liquefaction and possibly reconsolidation. For the specimens tested without reconsolidation, that simulated the soil immediately after an earthquake, the recovery is nearly non-existent but the drop in pore pressure during extension results in a small available strength. On the contrary, after reconsolidation, the increase in strength of the liquefied specimens is quite large, compared to the initial state, but with unchanged failure envelopes.

• International Journal of Naval Architecture and Ocean Engineering
• /
• 제7권4호
• /
• pp.720-738
• /
• 2015

This study examined the dynamic response of a subsea pipeline under an impact load to determine the effect of the seabed soil. A laboratory-scale soil-based pipeline impact test was carried out to investigate the pipeline deformation/strain as well as the interaction with the soil-pipeline. In addition, an impact test was simulated using the finite element technique, and the calculated strain was compared with the experimental results. During the simulation, the pipeline was described based on an elasto-plastic analysis, and the soil was modeled using the Mohr-Coulomb failure criterion. The results obtained were compared with ASME D31.8, and the differences between the analysis results and the rules were specifically investigated. Modified ASME formulae were proposed to calculate the precise structural behavior of a subsea pipeline under an impact load when considering sand- and clay-based seabed soils.

• Membrane and Water Treatment
• /
• 제14권2호
• /
• pp.95-106
• /
• 2023

In the developing country like India, groundwater is the main sources for household, irrigation and industrial use. Its contamination poses hydro-geological and environmental concern. The hazardous waste sites such as landfills can lead to contamination of ground water. The contaminants existing at such sites can eventually find ingress down through the soil and into the groundwater in case of leakage. It is necessary to understand the process of migration of pollutants through sub-surface porous medium for avoiding health risks. On this backdrop, the present paper investigates the behavior of pollutants' migration through porous media. The laboratory experiments were carried out on a soil-column model that represents porous media. Two different types of soils (standard sand and red soil) were considered as the media. Further, two different solutes, i.e., non-reactive and reactive, were used. The experimental results are simulated through numerical modeling. The percentage variation in the experimental and numerical results is found to be in the range of 0.75- 11.23 % and 0.84 - 1.26% in case of standard sand and red soil, respectively. While a close agreement is observed in most of the breakthrough curves obtained experimentally and numerically, good agreement is seen in either result in one case.

• 한국환경농학회지
• /
• 제15권2호
• /
• pp.217-222
• /
• 1996

인공산성비(pH 2.7)를 2-3일 간격으로 15회에 걸쳐 1회에 10mm씩 배추와 무의 잎, 토양, 잎과 토양에 처리하여 인공산성비의 처리위치가 가시적 피해증상, 잎의 엽록소 함량, 무기물의 함량, 그리고 수량에 미치는 영향을 검토한 결과는 다음과 같다. 1. 인공산성비를 잎에 처리할 때 배추와 무는 갈색 반점이 다소 발생하였으나 토양에 처리할 때는 피해증상이 없었다. 특히 배추는 결구가 되었을 때는 구의 잎 끝이 갈변하고, 잎에 흑갈색 반점이 발생하였으며, 심하면 잎 전체가 탈색되었다. 2. 인공산성비 처리는 배추 잎의 엽록소 함량을 증가시켰으나 무에서는 차이가 없었다. 3. 배추와 무 모두 N, P, K 함량과 배추의 황 함량은 인공산성비 처리위치간에 차이가 없었다. 그러나 무 잎중 황 함량은 잎이나 토양에 인공산성비를 처리한 것이 황 함량이 높았으며, 뿌리중 황 함량은 토양에 인공산성비를 처리한 것이 잎에 인공산성비를 처리한 것이나 인공산성비를 처리하지 않은 것보다 높았다. 4. 배추의 수량은 인공산성비의 영향을 받지 않았다. 그러나 무는 인공산성비에 의하여 수량이 감소하였는데 특히 잎에 인공산성비를 처리한 것은 뿌리의 수량을 현저히 감소시켰다.