• Journal of Korean Society on Water Environment
• /
• v.34 no.1
• /
• pp.77-83
• /
• 2018

This paper aims to evaluate the results of toxicity testing with Daphnia magna and Vibrio fischeri on wastewater samples which might be influenced by ion imbalance. The effluents from factories were found to be more toxic with high salinity levels than those from public wastewater treatment plant (WTP) and sewage treatment plant (SWP). Clion composition was highest in the effluent, in terms of percentage, which was followed by $Na^+$, $SO_4^{2-}$ and $Ca^{2+}$. $K^+$ and $Mg^{2+}$ ion was relatively low. The sensitivity of D. magna test results was higher than V. fischeri. Among samples which were proved by V. fischeri testing to be nontoxic, the composition ratio of each ion whether toxic samples or nontoxic samples which were decided by D. magna toxicity testing, were compared. $Na^+$, $K^+$, $Ca^{2+}$, $Mg^{2+}$ ion composition ratio showed high level in nontoxic samples whereas $SO_4^{2-}$ and $Cl^-$ ion composition ratio was high in toxic samples. Accordingly, $SO_4^{2-}$ and $Cl^-$ ion seemed to be considered the ions causing toxicity in effluent. Toxicity from some categories of industries (Mining of non-metallic minerals, Manufacture of basic organic petrochemicals, Manufacture of other basic organic chemicals, Manufacture of other chemical products etc.) seemed to be influenced by salinity. The Ion concentration in influent and effluent were similar. Concentration of $Na^+$, $Cl^-$, $K^+$, $Ca^{2+}$ ions were high in influent, however $Mg^{2+}$ and $SO_4^{2-}$ ions were high in effluent.

• Journal of the Korean Society of Groundwater Environment
• /
• v.7 no.2
• /
• pp.59-65
• /
• 2000

The vertical distribution of pore water pressure in the highly saturated sand layer under the oscillating water pressure is studied theoretically and experimentally. By the experiments it is shown that the water pressure acting on the sand surface propagates into the sand layer with the damping in amplitude and the lag in phase, and that the liquefaction, the state that the effective stress becomes zero, occurs under certain conditions. These experimental results are explained fairly well by the same theoretical treatment as for the ground water problems in the elastic aquifer. The main characteristics of liquefaction clarified by the analysis are as follows: 1) The depth of the liquified layer increases with the increase of the amplitude and the frequency of the oscillating water pressure. 2) The increase of the volume of the water and the air in the layer increases the liquified depth. Especially the very small amount of the air affects the liquefaction significantly. 3) The liquified depth decrease rapidly with the increase of the compressibility coefficient of the sand. 4) In the range beyond a certain value of the permeability coefficient the liquified depth decrease with the increase of the coefficient.

• Economic and Environmental Geology
• /
• v.36 no.1
• /
• pp.17-25
• /
• 2003

Researches were carried out to investigate the characteristics and concentration of heavy metal elements of stream water through Dongmyoung abandoned metal mine and soil adjacent to the mine. The pH range of water was 5.9∼7.1 that implies the water environment was acidic to neutral. The contents and distribution aspects of heavy metals in water samples varied with geochemical characteristics of element, but the concentration of heavy metals has the tendency of increase closer to the mine in general. The results of soil analysis show that total heavy metal concentration of agricultural soil near mine was far lower than those of ore tailing and dumping site. Therefore, the effects of the abandoned mine on stream water and agricultural products were supposed to be insignificant, particularly because the portion of absorbed carbonates and reducible fractions among total heavy metal concentration was relatively lower than the other. Since, however total heavy metal concentrations of mining site were relatively higher than those of adjacent region, there is a possibility of heavy metal difussion when the chemical environment of the site changes due to migration of surface and underground water. It is suggested that the preventive measures for water and soil pollution by the heavy metals would be considered around the region.

• Geomechanics and Engineering
• /
• v.13 no.6
• /
• pp.1011-1025
• /
• 2017

The geological conditions surrounding the Jijiapo Tunnel of the Three Gorges Fanba Highway project in Hubei Province are very complex. In this paper, a 3-D physical model was carried out to study the evolution process of filling-type fracture water inrush and mud gush based on the conditions of the section located between 16.040 km and 16.042 km of the Jijiapo Tunnel. The 3-D physical model was conducted to clarify the effect of the self-weight of the groundwater level and tunnel excavation during water inrush and mud gush. The results of the displacement, stress and seepage pressure of fracture and surrounding rock in the physical model were analyzed. In the physical model the results of the model test show that the rock displacement suddenly jumped after sustainable growth, rock stress and rock seepage suddenly decreased after continuous growth before water inrushing. Once water inrush occured, internal displacement of filler increased successively from bottom up, stress and seepage pressure of filler droped successively from bottom up, which presented as water inrush and mud gush of filling-type fracture was a evolving process from bottom up. The numerical study was compared with the model test to demonstrate the effectiveness and accuracy of the results of the model test.

• Korean Journal of Environmental Agriculture
• /
• v.5 no.1
• /
• pp.35-42
• /
• 1986

This study was carried out to investigate the distribution of arsenic (As) fractions in paddy soils in relation to some soil characteristics and to find out the relationship between As fractions in soil and As content in brown rice. Soils and rice samples were collected from paddy field adjacent to arsenic mining and refinery sites. Sequential extraction procedures were used to fractionate As in soils into the designated forms of water soluble-As, Al-As, Fe-As, Ca-As, and residual-As. The results obtained were as follows: 1. The percent distribution of As fractions in soil showed a wide difference depending on some soil properties. The relative abundance of the extractable inorganic As fractions was in the order of Fe-As>Al-As>Ca-As>Water soluble-As regardless of mining and refinery sites. Residual-As fraction was more abundant in mining site than in refinery site. 2. With increasing soil pH, the percent distribution of Fe-As and Al-As fractions were decreased, but that of Ca-As and Residual-As fractions increased. The percent distribution of Al-As fraction in soil was negatively correlated with soil CEC, but others showed positive relationships. 3. Active Al and Fe content, and exchangeable Ca content in soil were positively correlated with the percent distribution of Al-As, Fe-As, and Ca-As fractions in soil respectively, and higher correlation between them was shown in mining site than in refinery site. 4. Soil As fractions, except for water soluble-As, showed significant correlation with among each others and also with 1N HCl extration method using as the common soil As extractant in Korea. 5. Arsenic content in brown rice had highly significant correlation with Al-As fraction in soil and it also showed significant correlation with Fe-As and Ca-As fractions, Total-As, and 1N-HCl extractable As.

• Advances in concrete construction
• /
• v.14 no.3
• /
• pp.205-214
• /
• 2022

Due to seawater's physical and chemical deterioration effects on concrete structures, it is crucial to investigate the durability of these structures in marine environments. In some conditions, concrete structures are exposed to seawater from the first days of construction or because of the lack of potable water, part of the concrete curing stage is done with seawater. In this research, the effects of exposure to seawater after 7 days of curing in standard conditions were evaluated. To improve the durability of concrete, fly ash has been used as a substitute for a part of the cement in the mixing design. For this purpose, 5, 15, and 30% of the mixing design cement were replaced with type F fly ash, and the samples were examined after curing in seawater. The resistance of concrete against chloride ion penetration based on the rapid chloride penetration test (RCPT), water permeability based on the depth of water penetration under pressure, and water absorption test was done. The changes in the compressive strength of concrete in different curing conditions were also investigated. The results show that the curing in seawater has slightly reduced concrete resistance to chloride ion permeation. In the long-term, samples containing FA cured in seawater had up to 10% less resistance to chloride ion penetration. The amount of reduction in chloride ion penetration resistance was more for samples without FA. Whiles, for both curing conditions in the long-term up to 15%, FA improved the chloride ion penetration resistance up to 40%. Curing in seawater slightly increased the penetration depth of water under pressure in samples containing FA, while this increase was up to 12% for samples without FA. In the long-term the compressive strength of samples cured in seawater is not much different from the compressive strength of samples cured in plain water, while at the age of 28 days, due to seawater salts' accelerating effects the difference is more noticeable.

• Tunnel and Underground Space
• /
• v.28 no.5
• /
• pp.400-425
• /
• 2018

This study presents the research results and current status of the DECOVALEX-2019 project Task B. Task B named 'Fault slip modelling' is aiming at developing a numerical method to simulate the coupled hydro-mechanical behavior of fault, including slip or reactivation, induced by water injection. The first research step of Task B is a benchmark simulation which is designed for the modelling teams to familiarize themselves with the problem and to set up their own codes to reproduce the hydro-mechanical coupling between the fault hydraulic transmissivity and the mechanically-induced displacement. We reproduced the coupled hydro-mechanical process of fault slip using TOUGH-FLAC simulator. The fluid flow along a fault was modelled with solid elements and governed by Darcy's law with the cubic law in TOUGH2, whereas the mechanical behavior of a single fault was represented by creating interface elements between two separating rock blocks in FLAC3D. A methodology to formulate the hydro-mechanical coupling relations of two different hydraulic aperture models and link the solid element of TOUGH2 and the interface element of FLAC3D was suggested. In addition, we developed a coupling module to update the changes in geometric features (mesh) and hydrological properties of fault caused by water injection at every calculation step for TOUGH-FLAC simulator. Then, the transient responses of the fault, including elastic deformation, reactivation, progressive evolutions of pathway, pressure distribution and water injection rate, to stepwise pressurization were examined during the simulations. The results of the simulations suggest that the developed model can provide a reasonable prediction of the hydro-mechanical behavior related to fault reactivation. The numerical model will be enhanced by continuing collaboration and interaction with other research teams of DECOLVAEX-2019 Task B and validated using the field data from fault activation experiments in a further study.

• Journal of the Korean Association of Geographic Information Studies
• /
• v.2 no.3
• /
• pp.46-59
• /
• 1999

Remote sensing provides informations on the changes of the hydrological states and variables over with the temporal and spatial distribution to monitor hydrological conditions and changes for large area. Especially, it can extract a spatial distribution of hydrological parameters such as surface albedo, vegetation informations, and surface temperature to effectively manage water resources of the watershed. In this study, we analyzed the characteristic of temporal and spatial changes in surface hydrological parameters which is necessary to identify the spatial distribution of water resources. 5 Landsat TM data of 1995 which is collected for Bochong-chon watershed, located in the upper stream of Keum River, were used to estimate characteristics on the change of hydrological parameters and atmospheric correction was carried out using COST model. The study showed that the difference of the albedo by the land cover was very sensitive depending upon the change of sun elevation and the amount of water in the soil. The difference between the surface temperature analysis and the measured air temperature was from $2.5^{\circ}C$ to $3.86^{\circ}C$.

• Structural Engineering and Mechanics
• /
• v.81 no.2
• /
• pp.243-258
• /
• 2022

In this paper, tensile behavior of joint filling has been investigated under experimental test and numerical simulation (particle flow code). Two concrete slabs containing semi cylinder hole were prepared. These slabs were attached to each other by glue and one cubic specimen with dimension of 19 cm×15 cm×6 cm was prepared. This sample placed in the universal testing machine where the direct tensile stress can be applied to this specimen by implementing a special type of load transferring device which converts the applied compressive load to that of the tensile during the test. In the present work, two different joint filling thickness i.e., 3 mm and 6 mm were prepared and tested in the laboratory to measure their direct tensile strengths. Concurrent with experimental test, numerical simulation was performed to investigate the effect of hole diameter, length of edge notch, filling thickness and filling length on the tensile behavior of joint filling. Model dimension was 19 cm×15 cm. hole diameter was change in four different values of 2.5 cm, 5 cm, 7.5 cm and 10 cm. glue lengths were different based on the hole diameter, i.e., 12.5 cm for hole diameter of 2.5 cm, 10 cm for hole diameter of 5 cm, 7.5 cm for hole diameter of 7.5 cm and 5 cm for hole diameter of 10 cm. length of edge notch were changed in three different value i.e., 10%, 30% and 50% of glue length. Filling thickness were changed in three different value of 3 mm, 6 mm and 9 mm. Tensile strengths of glue and concrete were 2.37 MPa and 6.4 MPa, respectively. The load was applied at a constant rate of 1 kg/s. Results shows that hole diameter, length of edge notch, filling thickness and filling length have important effect on the tensile behavior of joint filling. In fixed glue thinks and fixed joint length, the tensile strength was decreased by increasing the hole diameter. Comparing the results showed that the strength, failure mechanism and fracture patterns obtained numerically and experimentally were similar for both cases.

• Tunnel and Underground Space
• /
• v.33 no.5
• /
• pp.388-398
• /
• 2023

The changes in groundwater flow due to mining development act as a contributing factor to major issues such as ground subsidence, strength reduction and collapse. For the sustainable mining development, measures for dealing with fluctuations in seasonal underground water inflow, power losses, pump damage, and unexpected increases in inflow must be put in place. In this study, the aim is to identify the causes of underground seepage through the examination of hydrological connectivity between the study area and nearby limestone mine. A tracer tes for assessing subsurface connectivity has been planned. A variety of tracers, such as dyes and ions, were applied in lab test to select the optimal tracer material, and a hydrological model of the study area was implemented through field test. Finally, the hydrological connectivity between the external stream and underground water in the mine was analyzed.