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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Korean Geoenvironmental Society
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Journal DOI :
Korean Geo-Environmental Society
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Volume & Issues
Volume 8, Issue 6 - Dec 2007
Volume 8, Issue 5 - Oct 2007
Volume 8, Issue 4 - Aug 2007
Volume 8, Issue 3 - Jun 2007
Volume 8, Issue 2 - Apr 2007
Volume 8, Issue 1 - Feb 2007
Selecting the target year
Geotechnical Characteristics of Prefabricated Vertical Drain System for Contaminated Soil Remediation
Shin, Eunchul ; Park, Jeongjun ;
Journal of the Korean Geoenvironmental Society , volume 8, issue 5, 2007, Pages 5~14
The quantity of noxious wastes generated by the growth in industrialization and population in all over the world and its potential hazards in subsurface environments are becoming increasingly significant. The extraction of the contaminant from the soil and movement of the water are restricted due to the low permeability and adsorption characteristics of the reclaimed soils. Incorporated technique with PVDs have been used for dewatering from fine-grained soils for the purpose of ground improvement by means of soil flushing and soil vapor extraction systems. This paper is to evaluate several key parameters that affected to the performance of the PVDs specifically with regard to: well resistance of PVD, zone of influence, and smear effects. In the feasibility of contaminant remediation was evaluated in pilot-scale laboratory experiments. Well resistance is affected on the vertical discharge capacity of the PVDs under the various vacuum pressures. The discharge capacity increases consistently in areal extents with higher applied vacuum up to a limiting vacuum pressure. The head values for each piezometer at different vacuum pressures show that the largest head loss occurs within 14 cm of the PVD. Air flow rates and head losses were measured for the PVD placed in the model test box and the gas permeability of the silty soils was calculated. Increasing the equivalent diameter results in a decrease in the calculated gas permeability. It is concluded that the gas permeability determined over the 1,500 to 2,000
flow rates are the most accurate values which yields gas permeability of about 3.152 Darcy.
Sewage Treatment Using Electric Field Pretreatment and Metal Membrane Microfiltration Process
Jung, Jongtae ; Kim, Jongoh ;
Journal of the Korean Geoenvironmental Society , volume 8, issue 5, 2007, Pages 15~21
This study was investigated to evaluate the effect of electric fields application for the reduction of membrane fouling, the inactivation of microorganisms and the enhancement of particle coagulation in microfiltration/coagulation. Cumulative permeate in the case with electric field treatment showed high value compared to the case without electric field. Particularly, the increase of HRT (Hydraulic retention time) showed the increase of cumulative permeate as well as the decrease of total resistance. By electric field treatment, the amount of small particle size less than 100
is increased and the survival fraction is reduced by the increase of electric field intensity. This may be attributed to the cleavage of particle or cytological destruction resulting from the inactivation of microorganism. Coagulant dosage of PAC compared with no electric field application could also be saved about 75% for the 95% of turbidity removal at 10 kV/cm.
Stiffness Degradation and Unconfined Strength of the Chemically Grouted Sand Subjected to Cyclic Shear
Kwon, Youngcheul ; Lee, Bongjik ; Bae, Wooseok ;
Journal of the Korean Geoenvironmental Society , volume 8, issue 5, 2007, Pages 23~29
The performance of the improved soil against liquefaction depends upon the chemical density, and it has been decided on the basis of the unconfined compressive strength of the improved soil up to date. On the other hand, several authors have proposed that the stiffness degradation could be treated as the clue for the judgment of the possibility of liquefaction. In this study, therefore, the stiffness degradation of the improved soil was estimated as the resistance against liquefaction by using the strain controlled cyclic triaxial test equipment. Based on the test results, it is concluded that the chemically treated sand can resist against the liquefaction in aspect of the reduction in effective stress and in the stiffness. Furthermore, even in the case of low chemical density, such as 2% in this study, has enough liquefaction resistance when compared with the 5~6% which often used in practical design. Considering this fact, the design of chemical density based on the unconfined strength can lead the overestimation in chemical density, and chemical density can be reduced when considering the stiffness reduction shown in this study.
Practical Design of the Sandmat Considering Consolidation Settlement Properties
Lee, Bongjik ; Kwon, Youngcheul ; Lee, Jongkyu ;
Journal of the Korean Geoenvironmental Society , volume 8, issue 5, 2007, Pages 31~38
The practical design method on sandmat uses a drain length, rate of consolidation settlement and permeability of sand as a major design factors. And, on the basis of this design process, it has been installed beneath the embankment with same thickness. However, the possibility the underestimation on the thickness of sandmat and the delayed drain have been pointed out by several authors caused by a differential settlement at the center and the end of embankment. In this study, therefore, the effect of the differential settlement on the thickness of sandmat and delayed drain through the numerical analysis of embankment was analyzed. As a result, a substantial sandmat thickness becomes small and the possibility of the delayed drain can be certified because of the development of differential settlement at the center and ends of embankment. As a countermeasure to overcome this problem, the applicability of the mound type sandmat was also investigated by the numerical method. It can be concluded that it maintains the designated substantial sandmat thickness throughout consolidation process, and is useful method to maintain the drain capacity. Especially, the mound type sandmat is effective method for a construction site where can cause a differential settlement such as embankment. Furthermore, it has to be designed on the basis of the accurate prediction of consolidation settlement as well as rate of consolidation settlement, drain length and permeability of sand.
Centrifuge Modeling on Lateral Flow of Soft Soils and Displacement of Bridge Abutment on the Composite Ground
Heo, Yol ; Park, Sunghun ; Yun, Seokhyun ; Kwon, Seonuk ;
Journal of the Korean Geoenvironmental Society , volume 8, issue 5, 2007, Pages 39~46
In this study, the centrifuge tests were performed to investigate the lateral flow behavior and stability of the ground improved by SCP. The centrifuge tests were fulfilled in the case of the back of abutment filled by EPS (case 1) and soil (case 2), and the potentiometer was installed on the abutment and embankment to measure the vertical and horizontal displacement at the top of abutment. As a result, the vertical displacement measured at the back of abutment was maximum 2.1 m, which was about 12% if compared with the height of embankment. In the case of the back of abutment filled by soil, the vertical and horizontal displacement measured at the top of abutment was 10 cm and 1.1 m, respectively, which exceeded the allowable horizontal displacement. On the other hand, in the case of the back of abutment filled by EPS, the vertical displacement of abutment did nor occur and the horizontal displacement was 1.4 cm. Therefore, the effect of SCP improvement with EPS method adopted to prevent the lateral flow and assure the stability of embankment on the soft ground was far superior.
An Experimental Study on Infiltration Characteristics of Facilities for Reducing Runoff Considering Surface Materials According to Housing Lot Developments
Im, Janghyuk ; Song, Jaiwoo ; Park, Sungsik ; Park, Hosang ;
Journal of the Korean Geoenvironmental Society , volume 8, issue 5, 2007, Pages 47~55
The increment of impermeable land area due to widespread land development caused the adverse impact on urban disaster prevention because it could decrease the peak rate of runoff as well as increase the runoff and peak flow during rainy period. To date, little research has been conducted on the infiltration characteristics and quantitative analysis because of their highly dependence on construction method, paving material, surface permeability, and field condition. Hence, this study was performed to investigate the infiltration characteristics of runoff-reducing facilities according to the type of paving material, which were examined using experimental apparatus with varying paving material and rainfall intensity, and thus to provide fundamental research data for runoff-reducing infiltration facilities. In this study, the infiltration characteristics were examined under the rainfall intensity of 20, 30, 50, 80, 100, 200 mm/hr for a variety type of paving materials such as concrete, asphalt, sand, grassland, and permeable paving material. The infiltration rate for permeable paving material was observed to be more than 93% under the condition of less than 200 mm/hr of rainfall intensity. For the compacted earth and grassland, the ultimate infiltration rate was estimated to be about 13% to 67%. The permeable paving material was concluded to be the most appropriate one for the runoff-reducing infiltration facilities because it has more favorable advantages than others in the light of infiltration volume, disaster prevention, and river training.
A Simple Design Method Considering Unsaturated Soils Characteristics of Slopes Under Rainfalls
Han, Taekon ; Kim, Hongtaek ; Baek, Seungcheol ; Kang, Inkyu ;
Journal of the Korean Geoenvironmental Society , volume 8, issue 5, 2007, Pages 57~65
Slope collapse occurs mostly at the rainy season or thawing season in Korea. From a engineer point of view, the design criterion in recent of soil slopes during the rainfall have a conservative tendency because a slope stability is evaluated in the condition that ground water level is located in the surface. However, for the rational design of soil slopes during rainfall, the raining conditions and the unsaturated soil characteristics of soil slopes have to be considered. For the unsaturated soil characteristics of soil slopes, the laboratory tests for unsaturated soils and the seepage analyses for the raining conditions have to be performed. Due to these difficulties, a conservative design of soil slopes in the current design criterion has been carried out. In this paper, therefore, a simple design method is proposed. The method is considered to the unsaturated soil characteristics and the results of seepage analysis without numerical analysis. To verify the suggested design method, it is compared with both analysis results by current design criterion and analysis results based on the seepage analysis. Through the comparative study, it was found that the current design criterion has been excessively conservative. Hence, simple design method in this study was evaluated as the rational design for the soil slopes during rainfall.