Stability of embankments constructed from soil mixed with stone dust in quarry reclamation     

Young-Suk Song  Kyeong-Su Kim  Kyu-Seok Woo 《Environmental Earth Sciences》2012,67(1):285-292

This study examines the stability of an embankment used in stone quarry reclamation built of local natural soil mixed with stone dust. Stone dust is a fine-grained and low-strength material, whereas soil is coarser with higher strength. Test results show that the shear strength and maximum dry unit weight of the mixed material increase with a decrease in the stone dust. After reviewing various domestic and international standards for slope stability, this study suggests a three-grade slope stability rating system (“unstable,” “requires attention” and “stable”) for embankments built of soil mixed with stone dust. A series of slope stability analysis aims to define stable heights, slope angles and mix ratios for such embankments. Safe slope gradients should be 1:1.8 or higher for 10 m high embankments. Embankments 15 m in height should use a mix ratio less than 50% and a slope gradient of 1:1.8 or higher. The safe dimensioning and design guideline values determined by this study should be useful for the construction of new, as well as the stability evaluation of existing embankments that have been made from mixed soils containing stone dust.  相似文献   

Finite element method for strong reflection of water waves     

Yong-Sik Cho  Woo-Chang Jeong  Seung-Buhm Woo   《Ocean Engineering》2004,31(5-6):653-667

In this study, the propagation of monochromatic water waves over an arbitrarily varying topography is numerically investigated. A finite element model is developed by formulating the diffraction of waves caused by depth changes. Not only the propagating mode but also the evanescent modes are included in the model. The model developed is applied to the study of strong reflection of monochromatic waves over a sinusoidally varying topography. Predicted reflection coefficients are compared with those of available laboratory experiments and the eigenfunction expansion method. A very good agreement is observed.  相似文献   

Early Observations by the GOES-13 Solar Extreme Ultraviolet Sensor (EUVS)     

J. S. Evans  D. J. Strickland  W. K. Woo  D. R. McMullin  S. P. Plunkett  R. A. Viereck  S. M. Hill  T. N. Woods  F. G. Eparvier 《Solar physics》2010,262(1):71-115

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Evolution and Sedimentation Mechanisms of Estuarine Beach in the Nakdong River Estuary,Korea: Natural and Human Impact     

Jeong  Joo Bong  Jung  Hoi-Soo  Lee  Jun-Ho  Park  Kyung Kyu  Kim  Seok Yun  Woo  Han Jun 《Ocean Science Journal》2022,57(3):451-466

Ocean Science Journal - Dadae Beach located in the Nakdong River estuary has been continuously evolving as the result of natural and anthropogenetic activities. Due to the geographic...  相似文献   

Harmful Dinoflagellate Prorocentrum donghaiense Lu is Widely Distributed Along the East China Sea and Korean Coastal Area     

Shin  Hyeon Ho  Li  Zhun  Seo  Min Ho  Soh  Ho Young  Lim  Weol Ae  Park  Jong Woo 《Ocean Science Journal》2019,54(4):685-691

Ocean Science Journal - There have been controversies regarding the taxonomy of Prorocentrum donghaiense, however Zhang et al. (2016) recently developed a probe with a quantitative real-time PCR...  相似文献   

Sequestration of arsenate from aqueous solution using 2-line ferrihydrite: equilibria,kinetics, and X-ray absorption spectroscopic analysis     

Woo Chun Lee  Soon-Oh Kim  James Ranville  Seong-Taek Yun  Sun Hee Choi 《Environmental Earth Sciences》2014,71(8):3307-3318

Arsenic(V), as the arsenate (AsO₄ ^3?) ion and its conjugate acids, has a strong affinity on Fe, Mn, and Al (oxyhydr)oxides and clay minerals. Removal of arsenate from aqueous solution by poorly crystalline ferrihydrite (hydrous ferric oxide) via a combination of macroscopic (equilibria and kinetics of sorption) and X-ray absorption spectroscopic studies was investigated. The removal of arsenate significantly decreased with increasing pH and sorption maxima of approximately 1.994 mmol/g (0.192 mol_As/mol_Fe) were achieved at pH 2.0. The Langmuir isotherm is most appropriate for arsenate sorption over the wide range of pH, indicating that arsenate sorption preferentially takes place at relatively homogenous and monolayer sites rather than heterogeneous and multilayer surfaces. The kinetic study demonstrated that arsenate sorption onto 2-line ferrihydrite is considerably fast, and sorption equilibrium was achieved within the reaction time of 2 h. X-ray absorption near-edge structure spectroscopy indicates no change in oxidation state of arsenate following interaction with the ferrihydrite surfaces. Extended X-ray absorption fine structure spectroscopy supports the efficient removal of arsenate by the 2-line ferrihydrite through the formation of highly stable inner-sphere surface complexes, such as bidentate binuclear corner-sharing (²C) and bidentate mononuclear edge-sharing (²E) complexes.  相似文献   

A developed soil column test device for measuring the electrical conductivity breakthrough curves     

Xiaoqiang Dong  Xiaofeng Liu  Heesoo Woo  Junboum Park 《Environmental Earth Sciences》2014,72(9):3715-3722

To obtain the breakthrough curves without efforts required in the sampling and chemical analysis, a new soil column test device was developed. The device can conduct time-continuous electrical conductivity (EC) measurements without disturbing the soil matrix at all stages of the test. This device is composed of soil column, channel selector, LCR meter, and data logger. The soil column employs three 4-electrode sensors installed at different positions. To verify its applicability, the electrical conductivity breakthrough curves at different distances have been obtained with the use of five different species influent solutions (KCl, NaCl, CaCl₂, MgCl₂, and seawater). Results showed that the EC breakthrough curves and the transport parameters (the pore-water velocity, the dispersion coefficient, and the dispersivity) are very reasonable, and understand the one-dimensional steady flow exactly. The developed soil column test device proposed in this study provides a nondestructive, convenient, and inexpensive means of obtaining EC breakthrough curves.  相似文献   

Feedback and the fundamental line of low-luminosity low-surface-brightness/dwarf galaxies     

Avishai Dekel  Joanna Woo 《Monthly notices of the Royal Astronomical Society》2003,344(4):1131-1144

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A semi‐analytical solution for groundwater responses to stream‐stage variations and tidal fluctuations in a coastal aquifer     

Kue‐Young Kim  Taehee Kim  Yongje Kim  Nam‐Chil Woo 《水文研究》2007,21(5):665-674

A two‐dimensional semi‐analytical solution to analyse stream–aquifer interactions in a coastal aquifer where groundwater level responds to tidal effects is presented. The conceptual model considered is a two‐dimensional subsurface system with stream and coastline boundaries at right angles. The dimensional and non‐dimensional boundary value problems were solved for water level in the aquifer by successive application of Laplace and Fourier transform techniques, and the results were obtained by numerical inversion of the transformed solution. The solution was then verified by reducing the solutions to one‐dimensional known problems and comparing the results with those from previous studies. Hypothetical examples were used to examine the characteristics of water‐level variations due to the variations in stream stage and the fluctuations in tide level. Sensitivity analysis indicated that streambed leakance has no influence over the amplitude of groundwater fluctuations, but that the effect of stream stage increases with increasing leakance. Little difference was observed in the water level for different aquifer penetration ratios with narrow stream width. Increases in streambed leakance caused increases in the effect of aquifer penetration by the stream on the water level. An increased specific yield value resulted in decreased amplitude of water fluctuations and mean water level, and showed that water‐level variations due to stream and tidal boundaries are sensitive to specific yield. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

Long term exposure to respirable volcanic ash on Montserrat: a time series simulation     

T. K. Hincks  W. P. Aspinall  P. J. Baxter  A. Searl  R. S. J. Sparks  G. Woo 《Bulletin of Volcanology》2006,68(3):266-284

Frequent ash fallout from long-lived eruptions (with active phases greater than 5 years) may lead to local populations experiencing unacceptably high cumulative exposures to respirable particulate matter. Ash from Montserrat has been shown to contain significant levels of cristobalite and other reactive agents that are associated with an increased risk of developing pneumoconiosis (including silicosis) and other long-term health problems. There are a number of difficulties associated with estimating risks in populations due to uncertain and wide ranging individual exposures, change in behaviour with time and the natural variation in individual response. Present estimates of risk in workers and other population groups are simplifications based on a limited number of exposure measurements taken on Montserrat (1996–1999), and exposure−response curves from epidemiological studies of coal workers exposed to siliceous dust. In this paper we present a method for calculating the long-term cumulative exposure to cristobalite from volcanic ash by Monte Carlo simulation. Code has been written to generate synthetic time series for volcanic activity, rainfall, ash deposition and erosion to give daily ash deposit values and cristobalite fraction at a range of locations. The daily mean personal exposure for PM₁₀ and cristobalite is obtained by sampling from a probability distribution, with distribution parameters dependent on occupation, ground deposit depth and daily weather conditions. Output from multiple runs is processed to calculate the exceedance probability for cumulative exposure over a range of occupation types, locations and exposure periods. Results are interpreted in terms of current occupational standards, and epidemiological exposure−response functions for silicosis are applied to quantify the long-term health risk. Assuming continuing volcanic activity, median risk of silicosis (profusion 1/0 or higher) for an average adult after 20 years continuous exposure is estimated to be approximately 0.5% in northern Montserrat to 1.6% in Cork Hill. The occupational group with the highest exposure to ash are gardeners, with a corresponding 2% to 4% risk of silicosis. In situations where opportunities for in-depth exposure studies are limited, computer simulations provide a good indication of risk based on current expert knowledge. By running the code for a range of input scenarios, the cost-benefit of mitigation measures (such as a programme of active ash clearance) can be estimated. Results also may be used to identify situations where full exposure studies or fieldwork would be beneficial. Editorial responsibility: J Stix  相似文献