• Title/Summary/Keyword: SOIL FEATURE

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Contact interface fiber section element: shallow foundation modeling

  • Limkatanyu, Suchart;Kwon, Minho;Prachasaree, Woraphot;Chaiviriyawong, Passagorn
    • Geomechanics and Engineering
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    • v.4 no.3
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    • pp.173-190
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    • 2012
  • With recent growing interests in the Performance-Based Seismic Design and Assessment Methodology, more realistic modeling of a structural system is deemed essential in analyzing, designing, and evaluating both newly constructed and existing buildings under seismic events. Consequently, a shallow foundation element becomes an essential constituent in the implementation of this seismic design and assessment methodology. In this paper, a contact interface fiber section element is presented for use in modeling soil-shallow foundation systems. The assumption of a rigid footing on a Winkler-based soil rests simply on the Euler-Bernoulli's hypothesis on sectional kinematics. Fiber section discretization is employed to represent the contact interface sectional response. The hyperbolic function provides an adequate means of representing the stress-deformation behavior of each soil fiber. The element is simple but efficient in representing salient features of the soil-shallow foundation system (sliding, settling, and rocking). Two experimental results from centrifuge-scale and full-scale cyclic loading tests on shallow foundations are used to illustrate the model characteristics and verify the accuracy of the model. Based on this comprehensive model validation, it is observed that the model performs quite satisfactorily. It resembles reasonably well the experimental results in terms of moment, shear, settlement, and rotation demands. The hysteretic behavior of moment-rotation responses and the rotation-settlement feature are also captured well by the model.

Nutrient Recycling : The European Experience - Review -

  • Hall, J.E.
    • Asian-Australasian Journal of Animal Sciences
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    • v.12 no.4
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    • pp.667-674
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    • 1999
  • Intensive livestock production has increased dramatically in Europe since the 1960s, particularly. in Northern and Central European countries, resulting in large increases in the nutrient pollution of surface and ground waters and in atmospheric emissions of ammonia. This has arisen due to inadequate management of the large amounts manure produced, particularly where there has been insufficient land area used for efficient nutrient reuse in crop production. Nutrient pollution from intensive livestock production has progressively degraded the quality of water resources in many parts of Europe, with eutrophication of many inland and coastal waters, as well as soil acidification and ecosystem degradation. These problems have been known for many years, and although there are various international agreements on transboundary pollution, it is largely left to individual countries to set and enforce standards. Consequently, a number of different approaches are employed, although the common feature of these is to encourage farmers to use the nutrients in animal manures efficiently according to crop requirements, which also reduces the potential for accumulation in soil and subsequent loss to the environment. This paper reviews nutrient production and use in Europe and some of the strategies employed to avoid and reduce nutrient pollution.

수압시험과 시추자료를 이용한 화강암지역의 수리적 특성

  • 김문수;함세영;성익환;이병대;류상민;정재열
    • Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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    • 2001.09a
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    • pp.231-234
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    • 2001
  • When constructing subsurface structures and/or wells, the precise estimates of hydraulic parameters must be obtained for operating safety and/or for developing necessary quantity of groundwater. Hydraulic conductivity is mainly subjected to the characteristics of fracture network in the fractured media such as fracture orientation and angle, fracture aperture and frequency, fracture length, interconnectivity of fractures, and filling material, feature of fracture plane. In this study we conducted water injection test at afferent depths on six boreholes drilled in granite of Mt. Geumjeong. hydraulic conductivity was calculated using Moye and Hvorslev methods. The relation between hydraulic conductivity and fracture frequency data obtained from acoustic televiewer and core log were analyzed. The result shows that the correlation between the hydraulic conductivity and the fracture frequency data obtained from acoustic televiewer is better than that with the core log.

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Analysis of Riparian Vegetation for the Location Character-Focus on Relationship between Microtopographical Feature and Soil Character- (하반 식생의 입지 적정성 분석-미지형 토양환경을 중심으로-)

  • 안홍규
    • Korean Journal of Environment and Ecology
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    • v.15 no.2
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    • pp.193-200
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    • 2001
  • 본 연구는 하반식생이 일정 지역에 정착할 때 밀접하게 관여하는 토양환경에 주목하였으며, 특히 하반 미지형 이라는 특수 지역에서 생각할수 있는 미지형 형성의 토양구조와 하반미지형이 식물에 미치는 토양수분, 그리고 식생과의 관계에 대하여 검토하였다. 그결과 각 미지형마다 그 퇴적상태가 다르며 이에따라 하반식생도 달리 나타났다. 또한 모두 조사구에 서 모래층 밑에는 반드시 자갈층의 단계를 반복하고 있는데 이는 반복된 과거의 홍수에 의한 것으로 판단된다. 따라서 미지형을 고려한 식생을 도입하여야 하며, 토양수분과 지라수위와 식생과의 관계는 하천마다 다르므로 현지 지형에 맞는 식생 도입이 요구된다. 앞으로 보다 지속적, 장기적 현장조사와 하천 수문, 수리학적 data의 축정에 따른 하반식생과 입지환경요인과의 관련성에 관한 연구의 축적이 필요하며, 이에 기초한 식생호안공법의 개발이 향후과제라 할 수 있다.

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Degradation of Phenanthrene by Sphingomonas sp. 1-21 Isolated from Oil-Contaminated Soil

  • Ryeom, Tai-Kyung;Lee, Il-Gyu;Son, Seung-Yeol;Ahn, Tae-Young
    • Journal of Microbiology and Biotechnology
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    • v.10 no.5
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    • pp.724-727
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    • 2000
  • A Phenanthrene-degrading bacterium, Strain 1-21 was isolated from oil-contaminated soil. This strain was a Gram-negative, aerobic, and rod-shaped bacterium, and exhibited a 99% sequence similarity of 16S rDNA to that of Sphingomonas subarctica. The major cellular fatty acid was a summed feature 7(18:1 w7c, 18:1 w9t, 18:1 s12t), which is a characteristic of the Sphingomonas species. When 200 and 1,000 ppm of phenanthrene was added as the sole carbon source, Strain 1-21 degraded 98% and 67% after 10 days of incubation, respectively. Futhermore, this strain was also able to utilized naphthalene and fluorene as sole carbon and energy sources.

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A study on the Damaged tree by the Inferior Drainage in a Prepared Housing Site (주택단지조성시 배수불량으로 인한 수목피해에 관한 연구 -평택 아파트단지를 중심으로 -)

  • 최용순;심경구
    • Journal of the Korean Institute of Landscape Architecture
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    • v.23 no.2
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    • pp.195-204
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    • 1995
  • This study is focused on the groping for the alternative ways in order to prevent the various bad factors caused by the Inferior environment on the planted trees. In the reclaimed paddy field which is planned to make a housing site, for example, we are trying to catch the problem about the special feature of the unharmonized drainage. And the survey gives the suitable way of planting trees. This survey was carried out in the three different area and could notice some phenomena : There are a few different conditions for water supply int\ulcorner the soil according to the height of the land-filling from the original ground and the slope of the planting area. And the imporant factor of the drainage effect is not the soil texture itself but the depth of the filling land. As a result of this survey, the study shows the economic alternative for reducing the demage of the planting trees which is due to drainage system.

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Evaluation of Minimum Depth Criterion and Reinforcement Effect of the Soil Cover in a Long-span Soil-steel Bridge (장지간 지중강판구조물의 최소토피고 평가 및 토피지반 보강에 대한 수치해석)

  • 이종구;조성민;정현식;김명모
    • Journal of the Korean Geotechnical Society
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    • v.20 no.5
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    • pp.67-78
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    • 2004
  • Soil-steel bridges are made of flexible corrugated steel plates buried in the well-compacted granular soil. One kind of possible collapses of these structures could be initiated by shear or tension failure in the soil cover subjected to vehicle loads. Current design codes provide the requirements for the minimum depth of the soil cover to avoid problems associated with soil cover failures. However, these requirements were developed for short span (less than 7.7 m) structures which are made of unstiffened plates of standard corrugation (150$\times$50 m). Numerical analyses were carried out to investigate the behavior of long span soil steel bridges according to thickness of the soil cover. The span of structures were up to 20 m and deep corrugated plates (381$\times$140 m) were used. The analysis showed that the minimum cover depth of 1.5 m could be sufficient to prevent the soil cover failure in the structures with a span exceeding 10 m. Additional analyses were performed to verify the reinforcement effect of the concrete relieving slab which can be a special feature to reduce the live-load effects. Analyses revealed that the bending moment of the conduit wall with a relieving slab was less than 20% of that without a relieving slab in a case of shallow soil cover conditions.

The Application of KOESWall System as a Temporary Structure (임시구조물로서 분리형 보강토 옹벽의 적용사레)

  • 김영윤
    • Proceedings of the Korean Geotechical Society Conference
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    • 2000.09a
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    • pp.53-58
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    • 2000
  • The KOESWall system that minimizes the horizontal deformation of reinforced wall effectively was developed bt E&S Eng. Co., Ltd. in 1999. Due to its systematical feature i.e. isolated construction method. KOESWall system is able to use as temporary structures more economically without the facing block. In this report, it is shown that the case history of KOESWall as a temporary soil retaining structure and the field measuremnets.

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Seismic stability analysis of tunnel face in purely cohesive soil by a pseudo-dynamic approach

  • Huang, Qi;Zou, Jin-feng;Qian, Ze-hang
    • Geomechanics and Engineering
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    • v.23 no.1
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    • pp.1-13
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    • 2020
  • To give a solution for seismic stability of tunnel faces subjected to earthquake ground shakings, the pseudo-dynamic approach is originally introduced to analyze tunnel face stability in this study. In the light of the upper-bound theorem of limit analysis, an advanced three-dimensional mechanism combined with pseudo-dynamic approach is proposed. Based on this mechanism, the required support pressure on tunnel face can be obtained by equaling external work rates to the internal energy dissipation and implementing an optimization searching procedure related to time. Both time and space feature of seismic waves are properly accounted for in the proposed mechanism. For this reason, the proposed mechanism can better represent the actual influence of seismic motion and has a remarkable advantage in evaluating the effects of vertical seismic acceleration, soil amplification factor, seismic wave period and initial phase difference on tunnel face stability. Furthermore, the pseudo-dynamic approach is compared with the pseudo-static approach. The difference between them is illustrated from a new but understandable perspective. The comparison demonstrates that the pseudo-static approach is a conservative method but still could provide precise enough results as the pseudo-dynamic approach if the value of seismic wavelengths is large or the height of soil structures is small.

A consistent FEM-Vlasov model for hyperbolic cooling towers on layered soil under unsymmetrical wind load

  • Karakas, Ali I.;Ozgan, Korhan;Daloglu, Ayse T.
    • Wind and Structures
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    • v.22 no.6
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    • pp.617-633
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    • 2016
  • In this paper, the analysis of hyperbolic cooling tower on elastic subsoil exposed to unsymmetrical wind loading is presented. Modified Vlasov foundation model is used to determine the soil parameters as a function of vertical deformation profile within subsoil. The iterative parameter updating procedure involves the use of Open Application Programming Interface (OAPI) feature of SAP2000 to provide two way data flow during execution. A computing tool coded in MATLAB employing OAPI is used to perform the analysis of hyperbolic cooling tower with supporting columns over a hollow annular raft founded on elastic subsoil. The analysis of such complex soil-structure system is investigated under self-weight and unsymmetrical wind load. The response of the cooling tower on elastic subsoil is compared with that of a tower that its supporting raft foundation is treated as fixed at the base. The results show that the effect of subsoil on the behavior of cooling tower is considerable at the top and bottom of the wall as well as supporting columns and raft foundation. The application of a full-size cooling tower has demonstrated that the procedure is simple, fast and can easily be implemented in practice.