• Journal of Soil and Groundwater Environment
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• v.17 no.6
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• pp.102-111
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• 2012

Fine suspended solids generated effluence from treatment process of mine drainage could destroy environment as the aesthetic landscapes, and depreciate water quality. Therefore, the purpose of this research is focused on process development applied the actual field for controlling fine suspended solids and heavy metals, and so lab-scale test was performed for inducement of basic data. The mine drainage used in this research was sampled in H mine located Jeongseon-gun, Gangwon-do. Concentration of suspended solid, arsenic, iron and manganese was exceeded the standard of contaminant limitation for the clean water, and particle size of suspended solid was less than 10 m as fine particle. Although hydraulic retention time of mine drainage for effective settling was required more than 6 hours, hydraulic retention time would be increased in winter season when the settling efficiency could be reduced because of viscosity decreasing. Moreover, installed inclination plate helped to increase settling efficiency of suspended solid about 48 %. Filtering media that was the most effective removal of suspended solids and heavy metal was decided granular activated carbon of 1~2 mm was the optimal size.

• Journal of Soil and Groundwater Environment
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• v.17 no.6
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• pp.112-118
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• 2012

Fine suspended solids from mine drainage draw attentions due to their potential adverse influences on the water quality, such as increasing turbidity and degrading aesthetic landscape. Currently, sand filter beds are adapted in some mine drainage treating systems. However, more efficient system is in demand, as the existing sand beds reveal some problems, such as frequent maintenance intervals. Various filtering mediums including fly ash, mine tailing aggregates and the sand were tested for improving the current system, using column experimental set-up. Mine drainage samples were collected from the current treating systems in the abandoned H coal mine. The experiment was run for 7 days. Suspended solids recorded as 100.9 mg/L and the value exceeds the current standard, 30 mg/L. Sand was proved to still be the optimum medium for the fine suspended solids, compared to fly ash and fly ash + sand. Mine tailing aggregates were placed at the exit of the columns, substituting gravels. The tailing aggregates is made by mine tailings and clay. Sand bed filters can also be improved by mixing granular activated carbon, which was found to be economical and efficient in the batch experiment, conducted at the same time.

• Geomechanics and Engineering
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• v.12 no.5
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• pp.831-847
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• 2017

Conventional geotechnical engineering soil binders such as ordinary cement or lime have environmental issues in terms of sustainable development. Thus, environmentally friendly materials have attracted considerable interest in modern geotechnical engineering. Microbial biopolymers are being actively developed in order to improve geotechnical engineering properties such as aggregate stability, strength, and hydraulic conductivity of various soil types. This study evaluates the geotechnical engineering shear behavior of sand treated with xanthan gum biopolymer through laboratory direct shear testing. Xanthan gum-sand mixtures with various xanthan gum content (percent to the mass of sand) and gel phases (initial, dried, and re-submerged) were considered. Xanthan gum content of 1.0% sufficiently improves the inter-particle cohesion of cohesionless sands 3.8 times and more (up to 14 times for dried state) than in the untreated (natural) condition, regardless of the xanthan gum gel condition. In general, the strength of xanthan gum-treated sand shows dependency with the rheology and phase of xanthan gum gels in inter-granular pores, which decreases in order as dried (biofilm state), initial (uniform hydrogel), and re-submerged (swollen hydrogel after drying) states. As xanthan gum hydrogels are pseudo-plastic, both inter-particle friction angle and cohesion of xanthan gum-treated sand decrease with water adsorbed swelling at large strain levels. However, for 2% xanthan gum-treated sands, the re-submerged state shows a higher strength than the initial state due to the gradual and non-uniform swelling behavior of highly concentrated biofilms.

• Journal of the Korean GEO-environmental Society
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• v.8 no.3
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• pp.67-75
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• 2007

This study was undertaken in order to investigate the load bearing capacity of raft in a piled raft through the laboratory model tests, the numerical and analytical analyses. The model tests were conducted about a piled raft, the free-standing pile group, a single pile, as well as a shallow foundation under equal conditions. The pile spacing and length, group type and soil conditions were varied in the laboratory model tests. The experimental results were compared with those by the commercial program, DEFPIG, conventional methods and Phung's method. According to this study, the behavior of piled raft was affected by pile spacing, length and soil conditions. Phung's method proved to be reliable for estimating the experimental results.

• Journal of Soil and Groundwater Environment
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• v.18 no.7
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• pp.54-62
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• 2013

Fine suspended solids and soluble heavy metals generated from mine drainage could destroy environment as the aesthetic landscapes, and depreciate water quality. Therefore, this research is focused on process development applied the actual field for controlling fine suspended solids and heavy metals, and so that bench-scale tests were performed for field application based on advanced researches. The field of mine drainage in this research was in H mine located Taebaek-si, Gangwon-do. The inclination plates were mounted 2 kinds of arrangement (octagon and radial types) in circle type settling basin. The inclination plates could be helped to settle of suspended solids; decreased 34% of suspended solids and 50% of turbidity in effluent. Radial type of inclination plates showed the results that is more efficient to settle of suspended solids (average to 3.45 mg/L) compared to octagon type. In the experiments to decrease retention time of mine drainage in settling basin from 6 hrs to 1.5 hrs, suspended solid concentration was exceeded to 30 mg/L as the standard for suspended solid at 10 days after the operation under tha retention time of 3hrs and 1.5hrs. In the tests for filtration, granular activated carbons were indicated the better effective to filtering and absorption of fine suspended solid and soluble heavy metals than anthracite.

• Korean Journal of Soil Science and Fertilizer
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• v.20 no.3
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• pp.217-221
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• 1987

Two trial products of monogranular compound fertilizer for red pepper under vinyl mulching cultivatin were made using the principal sources of urea, diammonium phosphate and muriate of potash in combination with fillers of treated human wastes (product I) and zeolite (Product II). A field experiment was carried out to evaluate their effects on red pepper and the results obtained were as follows. Red pepper plant growth and total red fruit yields in the trial products of one time basal application were better and higher than those of NPK split application of contrl plot. The increases of yield in the trial products might be due to steady supply of nutrients for the entire growing period. Therefore, one time basal dressing of a developed monogranular compound fertilizer for red pepper was applicable under vinyl mulching cultivation.

• Geotechnical Engineering
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• v.12 no.1
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• pp.63-72
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• 1996

The current practice in construction of reinforced earth retaining walls is to use a granular soil for the backfill material. When the material is available in site, the construetion cost can be remarkably reduced. As the weathered granite soils are abundant and widely distributed throughout the Korean peninsula: whether they are suitable or not as the backfill material is considered to be the most important key in economic construction of the wall. This paper investigates the grain size distribution of the weathered soils which locate at many places throughout the nation and then examines limitation of their use based on the specifications of different countries. The variaton of shear strength with both different fine contents and saturation is also investigated. It is known that the grain size distribution of most weathered soils are not satisfied with the general requirement. However their use is possible in wide range when the backfill keeps in unsaturated condition using good drainage facilities and 1 or pervious reinforcements.

• Geomechanics and Engineering
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• v.5 no.6
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• pp.575-594
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• 2013

Organic soils exhibit problematic properties such as high compressibility and low shear strength; these properties may cause differential settlement or failure in structures built on such soils. Organic soil removal or stabilization are the most important methods to overcome geotechnical problems related to peat soils' engineering characteristics. This paper presents soil mechanical intervention for stabilization of peat with sand columns and focuses on a comparison between the mechanical characteristics of undisturbed peat and peat stabilized with 20%, 30% and 40% of sand on the laboratory scale. Cylindrical columns were extruded in different diameters through a nearly undisturbed peat sample in the laboratory and filled with sand. By adding sand columns to peat, higher permeability, higher shear strength and a faster consolidation was achieved. The sample with 70% peat and 30% sand displayed the most reliable compressibility properties. This can be attributed to proper drainage provided by sand columns for peat in this specific percentage. It was observed that the granular texture of sand also increased the friction angle of peat. The addition of 30% sand led to the highest shear strength among all mixtures considered. The peat samples with 40% sand were sampled with two and three sand columns and tested in direct shear and consolidation tests to evaluate the influence of the number and geometry of sand columns. Samples with three sand columns showed higher compressibility and shear strength. Following the results of this laboratory study it appears that the introduction of sand columns could be suitable for geotechnical peat stabilization in the field scale.

• Geomechanics and Engineering
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• v.9 no.6
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• pp.757-774
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• 2015

Reinforcing soils with the geosynthetics have been shown to be an effective method for improving the uplift capacity of granular soils. The pull-out resistance of the reinforcing elements is one of the most notable factors in increasing the uplift capacity. In this paper, a new reinforcing element including the elements (anchors) attached to the ordinary geogrid for increasing the pull-out resistance of the reinforcement, is used. Thus, the reinforcement consists of the geogrid and anchors with the cylindrical plastic elements attached to it, namely grid-anchors. A three-dimensional numerical study, employing the commercial finite difference software FLAC-3D, was performed to investigate the uplift capacity of the pipelines buried in sand reinforced with this system. The models were used to investigate the effect of the pipe diameter, burial depth, soil density, number of the reinforcement layers, width of the reinforcement layer, and the stiffness of geogrid and anchors on the uplift resistance of the sandy soils. The outcomes reveal that, due to a developed longer failure surface, inclusion of grid-anchor system in a soil deposit outstandingly increases the uplift capacity. Compared to the multilayer reinforcement, the single layer reinforcement was more effective in enhancing the uplift capacity. Moreover, the efficiency of the reinforcement layer inclusion for uplift resistance in loose sand is higher than dense sand. Besides, the efficiency of reinforcement layer inclusion for uplift resistance in lower embedment ratios is higher. In addition, by increasing the pipe diameter, the efficiency of the reinforcement layer inclusion will be lower. Results demonstrate that, for the pipes with an outer diameter of 50 mm, the grid-anchor system of reinforcing can increase the uplift capacity 2.18 times greater than that for an ordinary geogrid and 3.20 times greater than that for non-reinforced sand.

• Korean Journal of Soil Science and Fertilizer
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• v.20 no.2
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• pp.97-100
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• 1987

Medium grade mongranular compound fertilizers for the crops under vinyl mulching cultivation were formulated using the principal materials of urea, DAP and MOP in combination with various fillers of zeolite, gypsum and treated human waste and granulated with waste liquid of glutamic acid fermentation as binder. The ratios of $N-P_2O_5-K_2O$ of trial products were 12-10-11.5 for red pepper, 8-8-6 for sesame and 4-9-14 for peanut. The rate of dissolution of trial products was comparatively low in water. The product for red pepper had N dissolution rate of 80 percent during 24 hrs. 70 for peanut and 55 for seasame. The optimum dissolution rate has reported to be 50 percent by the standard laboratory dissolution test for 24 hrs. in water. Therefore, the slowly released characteristics were obtained with the products that had 24 hrs. dissolution of 70 to 60 percent. One time basal application of trial products could readily be justified under muching cultivation.