• Title/Summary/Keyword: Soil structure interaction

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Bioremediation of Oil-Contaminated Soil Using an Oil-Degrading Rhizobacterium Rhodococcus sp.412 and Zea mays. (유류 분해 근권세균 Rhodococcus sp. 412와 옥수수를 활용한 유류 오염 토양의 정화)

  • Hong, Sun-Hwa;Park, Hae-Lim;Ko, U-Ri;Yoo, Jae-Jun;Cho, Kyung-Suk
    • Microbiology and Biotechnology Letters
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    • v.35 no.2
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    • pp.150-157
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    • 2007
  • The advanced bioremediation of diesel-contaminated soil through the exploration of bacterial interaction with plants was studied. A diesel-degrading rhizobacterium, Rhodococcus sp.412, and a plant species, Zea mays, having tolerant against diesel was selected. Zea mays was seeded in uncontaminated soil or diesel-contaminated soil with or without Rhodococcus sp. 412. After cultivating for 30 days, the growth of Zea mays in the contaminated soil inoculated with Rhodococcus sp. 412 was better than that in the contaminated soil without the bacterium. The residual diesel concentrations were lowered by seeding Zea mays or inoculating Rhodococctis sp. 412. These results Indicate that the simultaneous use of Zea mays and Rhodococcus sp. 412 can give beneficial effect to the remediation of oil-contaminated soil. Bacterial community was characterized using a 16S rDNA PCR and denaturing gradient gel electrophoresis (DGGE) fingerprinting method. The similarities of DGGE fingerprints were $20.8{\sim}39.9%$ between the uncontaminated soil and diesel contaminated soil. The similarities of DGGE fingerprints were $21.9%{\sim}53.6%$ between the uncontaminated soil samples, and $31.6%{\sim}50.0%$ between the diesel-contaminated soil samples. This results indicated that the structure of bacterial community was significantly influence by diesel contamination.

Responses of Soil Chemical Properties and Microbiota to Elevated Temperature under Flooded Conditions (상승온도에 의한 담수토양의 미생물상 및 화학성 변화)

  • Eo, Jinu;Hong, Seung-Chang;Kim, Myung-Hyun;Choi, Soon-Kun;Kim, Min-Kyeong;Jung, Goo-Bok;So, Kyu-Ho
    • Korean Journal of Environmental Agriculture
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    • v.35 no.1
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    • pp.32-38
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    • 2016
  • BACKGROUND: Our study aims to investigate the impact of temperature on the abundance and structure of soil microbial community in a temperature gradient tunnel.METHODS AND RESULTS: To investigate the interaction between temperature and input of C and N, rice straw and urea were applied to the study plots, respectively. We also studied the impact of plants by comparing plots cultivated with rice and unplanted plots. Soil microbial response was measured using the phospholipid fatty acid (PLFA) analysis. Soil chemical properties, including pH and ammonia and phosphate concentrations were influenced by warming and material addition. Microbial PLFA was partially influenced by material inputs, and actinomycetes PLFA was decreased by warming. In cultivated rice plots, an increase in the carbon to nitrogen ratio illustrated the effect of plant on microbiota caused by carbon addition through the root residues. Results from the principal component analysis of PLFA data showed that warmed and control plots applied with rice straw could be separated by principal component analysis.CONCLUSION: Our results suggest that plant influence both the microbial community structure and abundance, and temperature change has a minimal impact on soil microorganisms in flooded soil.

Ground Vibration Analysis for Light Rail Transit on Bridges (교량구간에서의 경량전철에 의한 지반진동 해석)

  • 김두기;이종재;윤정방;김두훈
    • Journal of the Korean Geotechnical Society
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    • v.16 no.4
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    • pp.71-82
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    • 2000
  • Ground vibration analysis methods for Light Rail Transit(LRT) on bridges are studied. LRT loads acting on the piers are evaluated considering interactions between trains and a bridge. Two dimensional in-plane and axisymmetric wave propagations are used in ground vibration analyses, and then the results of them are compared one another. A modified axisymmetric method is presented, which can consider the effect of the train loadings on a series of piers as the train moves. Parametric studies are carried out for various train speeds, bridge types and geotechnical conditions to investigate the characteristics of ground vibrations.

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Capacity-spectrum push-over analysis of rock-lining interaction model for seismic evaluation of tunnels

  • Sina Majidian;Serkan Tapkin;Emre Tercan
    • Earthquakes and Structures
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    • v.26 no.5
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    • pp.327-336
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    • 2024
  • Evaluation of tunnel performance in seismic-prone areas demands efficient means of estimating performance at different hazard levels. The present study introduces an innovative push-over analysis approach which employs the standard earthquake spectrum to simulate the performance of a tunnel. The numerical simulation has taken into account the lining and surrounding rock to calculate the rock-tunnel interaction subjected to a static push-over displacement regime. Elastic perfectly plastic models for the lining and hardening strain rock medium were used to portray the development of plastic hinges, nonlinear deformation, and performance of the tunnel structure. Separately using a computational algorithm, the non-linear response spectrum was approximated from the average shear strain of the rock model. A NATM tunnel in Turkey was chosen for parametric study. A seismic performance curve and two performance thresholds are introduced that are based on the proposed nonlinear seismic static loading approach and the formation of plastic hinges. The tunnel model was also subjected to a harmonic excitation with a smooth response spectrum and different amplitudes in the fully-dynamic phase to assess the accuracy of the approach. The parametric study investigated the effects of the lining stiffness and capacity and soil stiffness on the seismic performance of the tunnel.

Observation of Stylostome Formation in the Striped-field Mouse (Apodemus agrarius Pallas) Skin by Chigger Feeding (털진드기 흡혈에 의한 등줄쥐 피부의 흡입관 형성 관찰)

  • Lee, In-Yong;Yoon, Sang-Sun;Lee, Won-Ja;Sin, Hee-Kwan;Lee, Won-Koo
    • The Korean Journal of Soil Zoology
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    • v.11 no.1_2
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    • pp.1-6
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    • 2006
  • The chigger is of importance to humans and animals as an irritating pest and a crucial vector of disease. We observed stylostome formation by larvae of Leptotrombidium pallidum in parasitized striped-field mouse (Apodemus agarius) pinna skin. The stylostome formations were also examined in detail by electron microscopy. The proximal and middle parts of the stylostome were formed as a rod-like structure containing a canal. The stylostome was coated with thick degenerated epidermal cells, and seemed to be formed a hyperplastic epidermis. The stylostome formation may result from an interaction between larval secretions and the host tissue. According to histological and morphological characteristics, the stylostome exhibited considerable inflammation in the epidermis and similar reactivity.

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Innovative approach to determine the minimum wall thickness of flexible buried pipes

  • Alzabeebee, Saif;Chapman, David N.;Faramarzi, Asaad
    • Geomechanics and Engineering
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    • v.15 no.2
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    • pp.755-767
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    • 2018
  • This paper uses a finite element based approach to provide a comprehensive understanding to the behaviour and the design performance of buried uPVC pipes with different diameters. It also investigates pipes with good and poor haunch support and proposes minimum safe wall thicknesses for these pipes. The results for pipes with good haunch support showed that the maximum pipe wall stress and deformation increase as the diameter increased. The results for pipes with poor haunch support showed an increase in the dependency of the developed vertical displacement on the haunch support as the diameter or the backfill height increased. Additionally, poor haunch support was found to increase the soil pressure, with the effect increasing as the diameter increased. The design of uPVC pipes for both poor and good haunch support was found to be governed by critical buckling. A key outcome is a new design chart for the minimum wall thickness, which enables the robust and economic design of buried uPVC pipes. Importantly, the methodology adopted in this study can also be applied to the design of flexible pipes manufactured from other materials, buried under different conditions and subjected to different loading arrangements.

The Characteristics of Various Stress in Cohesionless Soil with the Rammed Aggregate Pier (짧은 쇄석다짐말뚝(RAP)이 설치된 사질토지반의 응력변화 특성)

  • Chun, Byung-Sik;Kim, Kyung-Min;Kim, Jun-Ho
    • Proceedings of the Korean Geotechical Society Conference
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    • 2005.03a
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    • pp.1108-1117
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    • 2005
  • RAP(rammed aggregate pier) method which is intermediate foundation of deep and shallow foundation is used to improve the ground with high compaction energy. This method is widely spread around the world, but there are few examples and systemic researches for failure mechanism and bearing capacity of this method are not organized yet. In this paper, soil laboratory tests were carried out to evaluate the applicability of RAP method as the foundation of a structure. And the bearing capacity and the failure mechanism of RAP method were studied with respect to various relative densities(35%, 65%, 90%), diameters(45mm, 60mm) and lengths(20cm, 30cm, 40cm). As results, stress concentration ratio decreased as diameter of RAP was increasing or length of RAP was decreased or relative density was decreased. however these results were not always constant. because systematic interaction between relative density and diameter and length of RAP can affect stress concentration ratio, more studies on stress concentration ratio are needed throughout laboratory and field tests.

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A Suggestion of an Empirical Equation for Shear Modulus Reduction Curve Estimation of Sandy Soils (사질토 전단탄성계수 감소곡선 산정을 위한 경험식 제안)

  • Park, Dug-Keun
    • Journal of the Korean Geotechnical Society
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    • v.18 no.3
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    • pp.126-126
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    • 2002
  • In dynamic analyses such as seismic ground response and soil-structure interaction problems, it is very crucial to obtain accurate dynamic shear modulus of soil deposit. In this study, an extensive data base of available experimental data is compiled and reanalyzed to establish a simple empirical formula for the dynamic shear modulus reduction curve to cover wide range of strain for sandy soils. The proposed empirical equation is to represent the dynamic shear modulus degradation with strain in terms of low-amplitude dynamic shear modulus and effective mean confining Pressure, since those factors have the most significant effect on the Position and shape of the shear modulus reduction curve for nonelastic soils. If low-amplitude shear modulus is measured, degraded modulus at any shear strain amplitude can be calculated using the proposed equation.

A Suggestion of an Empirical Equation for Shear Modulus Reduction Curve Estimation of Sandy Soils (사질토 전단탄성계수 감소곡선 산정을 위한 경험식 제안)

  • Park, Dug-Keun
    • Journal of the Korean Geotechnical Society
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    • v.18 no.3
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    • pp.127-138
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    • 2002
  • In dynamic analyses such as seismic ground response and soil-structure interaction problems, it is very crucial to obtain accurate dynamic shear modulus of soil deposit. In this study, an extensive data base of available experimental data is compiled and reanalyzed to establish a simple empirical formula for the dynamic shear modulus reduction curve to cover wide range of strain for sandy soils. The proposed empirical equation is to represent the dynamic shear modulus degradation with strain in terms of low-amplitude dynamic shear modulus and effective mean confining Pressure, since those factors have the most significant effect on the Position and shape of the shear modulus reduction curve for nonelastic soils. If low-amplitude shear modulus is measured, degraded modulus at any shear strain amplitude can be calculated using the proposed equation.

Advanced procedure for estimation of pipeline embedment on soft clay seabed

  • Yu, S.Y.;Choi, H.S.;Park, K.S.;Kim, Y.T.;Kim, D.K.
    • Structural Engineering and Mechanics
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    • v.62 no.4
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    • pp.381-389
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    • 2017
  • In the present study, the advanced procedure has been proposed to estimate higher accuracy of embedment of pipes that are installed on soft clay seabed. Numerical simulation by OrcaFlex simulation code was performed to investigate dynamic seabed embedment, and two steps, i.e., static and dynamic analysis, were adopted. In total, four empirical curves were developed to estimate the seabed embedment including dynamic phenomena, i.e., behaviour of vessel, environmental condition, and behaviour of nonlinear soil. The obtained results were compared with existing methods (named general method) such as design code or guideline to examine the difference of seabed embedment for existing and advance methods. Once this process was carried out for each case, a diagram for estimating seabed embedment was established. The applicability of the proposed method was verified through applied examples with field survey data. This method will be very useful in predicting seabed embedment on soft clay, and the structural behaviours of installed subsea pipelines can be changed by the obtained seabed embedment in association with on-bottom stability, free span, and many others.