• Earthquakes and Structures
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• v.14 no.4
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• pp.285-295
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• 2018

In this study, the effect of local site conditions (site class and site amplifications) and structural variability are investigated on fragility functions of typical building structures. The study area is chosen as Eastern Turkey. The fragility functions are developed using site-specific uniform hazard spectrum (UHS). The site-specific UHS is obtained based on simulated ground motions. The implementation of ground motion simulation into seismic hazard assessment has the advantage of investigating detailed local site effects. The typical residential buildings in Erzincan are represented by equivalent single degree of freedom systems (ESDOFs). Predictive equations are accomplished for structural seismic demands of ESDOFs to derive fragility functions in a straightforward manner. To study the sensitivity of fragility curves to site class, two sites on soft and stiff soil are taken into account. Two alternative site amplification functions known as generic and theoretical site amplifications are examined for these two sites. The reinforced concrete frames located on soft soil display larger fragilities than those on stiff soil. Theoretical site amplification mostly leads to larger fragilities than generic site amplification more evidently for reinforced concrete buildings. Additionally, structural variability of ESDOFs is generally observed to increase the fragility especially for rigid structural models.

• Journal of Soil and Groundwater Environment
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• v.17 no.1
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• pp.47-54
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• 2012

When quicklime is added into soil for various purposes, abrupt changes in soil chemistry may affect essential ecological functions played by indigenous bacterial communities in soil. The magnitude of influence was estimated by observing changes in abundance and diversity of soil bacteria after quicklime treatment. When several soil samples were treated up to 20% (w/w) quicklime, plate count of viable cells ranged $10^2{\sim}10^3$ CFU $g^{-1}$, showing a reduction of more than $10^4$ times from viable counts of the untreated sample. Diversity of the bacterial isolates that survived after quicklime treatment was analyzed by conducting $GTG_5$ rep-PCR fingerprinting. There were only two types of fingerprints common to both 5% and 20% quicklime samples, implying that bacteria surviving at different strength of quicklime treatment differed depending on their tolerance to quicklime-treated condition. Isolates surviving the quicklime treatments were further characterized by Gram staining and endospore staining. All isolates were found to be Gram positive bacteria, and 85.4% of them displayed endospores state. In conclusion, most bacteria surviving quicklime treatment appear to be endospores. This finding suggests that most of ecological functions of bacteria in soil are lost with quicklime treatment.

• Korean Journal of Soil Science and Fertilizer
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• v.49 no.6
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• pp.655-661
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• 2016

Relationships between saturated conductivity (Ks) and separate contents were evaluated from 44 soil series of arable lands: 18 for paddy fields and 26 for upland crop fields. Saturated hydraulic conductivities of A, B, and C horizons were determined with tension infiltrometer and Guelph permeameter in situ. Sand, silt, clay, and organic matter content of each horizon were analyzed. Based on correlation analysis, sand separate had a positive relationship with Ks for both paddy (r=0.27, p=0.017) and upland fields (r=0.24. p=0.030). Clay content had a negative relationship with Ks for paddy soils (r=-0.32, p=0.005) while significant correlation between them was not found for upland crop fields (r=-0.20, p=0.07). Organic matter content showed a positive relationship with Ks only for upland crop fields (r=0.33, p=0.002). Due to low correlation coefficients between separate contents and Ks, performance of pedotransfer functions was not enough to estimate Ks. It implies that hydraulic properties of arable lands were affected by other factors rather than particle characteristics. Platy structure and plow pan were suggested to limit Ks of paddy fields. Soil compaction and diversity of parent materials were proposed to influence Ks of upland crop fields. It suggests that genetic processes and artificial managements should be included in pedotransfer functions to estimate hydraulic properties appropriately.

• Journal of Soil and Groundwater Environment
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• v.17 no.4
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• pp.36-43
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• 2012

Various methods are used to remediate soil contaminated with heavy metals or petroleum. In recent years, harsh physical and chemical remediation methods are being used to increase remediation efficiency, however, such processes could affect soil properties and degrade the ecological functions of the soil. Effects of soil washing, thermal desorption, and land farming, which are the most frequently used remediation methods, on the physicochemical properties of remediated soil were investigated in this study. For soils smaller than 2 mm, the soil texture were changed from sandy clay loam to sandy loam because of the decrease in the clay content after soil washing, and from loamy sand to sandy loam because of the decrease in the sand content and increase in silt content during thermal desorption, however, the soil texture remained unchanged after land farming process. The water-holding capacity, organic matter content, and total nitrogen concentration of the tested soil decreased after soil washing. A change in soil color and an increase in the available phosphate concentration were observed after thermal desorption. Exchangeable cations, total nitrogen, and available phosphate concentration were found to decrease after land farming; these components were probably used by microorganisms during as well as after the land farming process because microbial processes remain active even after land farming. A study of these changes can provide information useful for the reuse of remediated soil. However, it is insufficient to assess only soil physicochemical properties from the viewpoint of the reuse of remediated soil. Potential risks and ecological functions of remediated soil should also be considered to realize sustainable soil use.

• Structural Engineering and Mechanics
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• v.83 no.3
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• pp.377-386
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• 2022

This paper considers dynamic impedance functions and presents a detailed analysis of the soil plasticity influence on the pile-group foundation dynamic response. A three-dimensional finite element model is proposed, and a calculation method considering the time domain is detailed for the nonlinear dynamic impedance functions. The soil mass is modeled as continuum elastoplastic solid using the Mohr-Coulomb shear failure criterion. The piles are modeled as continuum solids and the slab as a structural plate-type element. Quiet boundaries are implemented to avoid wave reflection on the boundaries. The model and method of analysis are validated by comparison with those published on literature. Numerical results are presented in terms of horizontal and vertical nonlinear dynamic impedances as a function of the shear soil parameters (cohesion and internal friction angle), pile spacing ratio and frequencies of the dynamic signal.

• Earthquakes and Structures
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• v.16 no.1
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• pp.109-118
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• 2019

This study, analyses the seismic response for a rigid massless square foundation resting on a viscoelastic soil layer limited by rigid bedrock. The foundation is subjected either to externally applied forces or to obliquely incident seismic body or surface harmonic seismic waves P, SV and SH. A 3-D frequency domain BEM formulation in conjunction with the thin layer method (TLM) is adapted here for the solution of elastodynamic problems and used for obtained the seismic response. The mathematical approach is based on the method of integral equations in the frequency domain using the formalism of Green's functions (Kausel and Peck 1982) for layered soil, the impedance functions are calculated by the compatibility condition. In this study, The key step is the characterization of the soil-foundation interaction with the input motion matrix. For each frequency the impedance matrix connects the applied forces to the resulting displacement, and the input motion matrix connects the displacement vector of the foundation to amplitudes of the free field motion. This approach has been applied to analyze the effect of soil-structure interaction on the seismic response of the foundation resting on a viscoelastic soil layer limited by rigid bedrock.

• Korean Journal of Organic Agriculture
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• v.19 no.spc
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• pp.108-110
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• 2011

In order to evaluation of beneficial functions for organic farming, we have divided beneficial functions as 9 sub-functions such as flooding control, fostering water resources, purifying the air, mitigating summer climate, purifying water quality, decreasing soil erosion, accumulating soil carbon, conserving biodiversity, and preventing accidents from pesticides. And they were quantified by searching related repots and statistics, and surveying fields. Organic farming, especially organic paddy farming, showed that some functions like fostering water resources, accumulating soil carbon, conserving biodiversity, and preventing accidents from pesticides were higher than conventional paddy farming, while the others were almost similar. The fostering water resources function was evaluated as 4,297 ton $ha^{-1}\;year^{-1}$ to increase about 3.6% comparing with that of conventional farming. New function for accumulating soil carbon at organic paddy fields has been assessed by 4.67 ton $ha^{-1}$ in terms of long periods over 10 years. Considering area of organic paddy farming in Korea and value of carbon price, it was evaluated monetary value as 22.4 to 84.1 billion won using replaced method. It could be also evaluated that flooding control, fostering water resources, purifying the air, mitigating summer climate, purifying water quality, decreasing soil erosion, and preventing accidents from pesticides were 2,980, 123.4, 482.6, 87.5, 0.9, 55.6, and 284.1 billion won, respectively. Conserving biodiversity function would be very big at organic farming though it couldn't be evaluated as monetary value.

• Journal of the Korean Geotechnical Society
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• v.26 no.10
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• pp.49-60
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• 2010

Unsaturated permeability function is an important factor in the design and analysis of various unsaturated soil structures. Generally the permeability characteristics decrease as the mat ric suction increases and the trend is similar to water retention characteristics of a soil. The permeability of unsaturated soils can be obtained directly by laboratory tests or indirectly by estimation methods from other soil properties. For unsaturated soils sampled from 7 areas in KOREA, SWCCs and unsaturated permeability functions were obtained by experimental tests. The unsaturated permeability results were also compared with the unsaturated permeability functions derived from the SWCCs theoretically. However, the current estimation models of unsaturated permeability function did not express the unsaturated permeability characteristics. Therefore, the FXK-M permeability function was modified to predict more accurate permeability functions for Korean weathered soils using a correction factor that can be calculated from the air-entry value of SWCC. The new estimation model resulted in good agreements for all tested soils.

• Computers and Concrete
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• v.6 no.1
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• pp.79-93
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• 2009

In the present paper, a methodology has been presented for the reliability assessment of concrete barriers that lie at a certain depth in the soil, and a missile (a rigid projectile) impacts the top of the soil cover normally, and subsequently after penetrating the soil cover completely it hits the barrier with certain striking velocity. For this purpose, using expressions available in the literature, striking velocity of missile at any depth of soil has been derived and then expressions for the depths of penetration in crater and tunnel region of concrete barrier have been deduced. These depths of penetration have been employed for the derivation of limit state functions. Using the derived limit state functions reliability assessment of underground concrete barrier has then been carried out through First Order Reliability Method (FORM). To study the influence of various random variables on barrier reliability, sensitivity analysis has also been carried out. In addition, a number of parametric studies is conducted to obtain the results of practical interest.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.09a
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• pp.97-100
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• 2004

Multivariate Newton Raphson method is developed to perform the particle tracking in the three dimensional area using four objective functions. In this method, three variables are solved to compute target point and actual and real tracking time. The simulated pathlines in various types of three dimensional elements are well matched with exact pathline.