• The Journal of Engineering Geology
• /
• v.13 no.2
• /
• pp.157-170
• /
• 2003

This study is performed to investigate the cause of slope failure and to suggest suitable stabilization methods for the failed rock slopes. The slope which is located along the national highway between Maesan and Kakok in Dangjin-gun failed during the construction of roads. Site investigation, drilling program, field measurements, rainfall records, and stability analyses are used to investigate the cause of the slope failure. The problem determining the cut-slope angle based on the existing design manual for the construction of roads is reviewed based on the case history given in this paper. If weakness layer and geological structures such as folds and faults are developed in a slope, slope failure is possible even though the direction of slope and the direction of discontinuities depart more than $30^{\circ}$.

• The Journal of Engineering Geology
• /
• v.2 no.1
• /
• pp.70-91
• /
• 1992

Cheju and Oahu island are similar in geology, characterized by same types of volcanic activities during the late Tertiary to the early Quaternary. The occurrence of groundwater in both islands depend on two basic elements, permeability of volcanic rocks and precipitation. However, groundwater occurrence in Oahu is much more controlled by dike complex in the regional volcanic rocks. There are two different types of groundwater in both islands. One is perched groundwater standing at any high altitude, and the other is basal groundwater developed near the coastal area. The groundwater quality of Cheju island is good in general for drinking. But many wells near the eastern coastal area are salt intruded due to over pumping activities and the area of salt water intrusion has increased landward from the year of 1970. This feature of salt water contamination is similar at Pearl Harbour in Oahu island. In order to prevent this salt water contamination into fresh groundwater reservoir on Cheju island, it is urgently asked to make groundwater flow study along the coastal area on terms of groundwater potentials and their maximum ultimate exploration.

• The Journal of Engineering Geology
• /
• v.25 no.2
• /
• pp.251-263
• /
• 2015

Geological mapping, borehole drilling, electrical resistivity, and seismic tomography surveys were conducted in order to map underground cavities and better understand the mechanisms driving subsidence in a limestone region in Korea. Limestone outcrops in the study area generally alternate between calcite-rich and calcite-poor rock. The results reveal that in areas experiencing subsidence, cavities occur mainly around soil-rock boundaries at depths of 7~14 m. These results are based on comparative analyses of electrical resistivity, seismic tomography, and borehole logging data. The volumes of the cavities are relatively small in a range of 558~835 ㎥ and they have a shape typical of suffosion sinkholes, which are typically found where sandy soils overlie bedrock cavities.

• The Journal of Engineering Geology
• /
• v.18 no.1
• /
• pp.7-16
• /
• 2008

Limestone area have mostly certain geological defects such as the internal cavities due to melting and fractured zone by external pressures. Especially, in case of constructing grand bridge, the treatment of the limestone cavities area having the geological defects is inevitable. In order to reduce foundation settlement and to reinforce the ground in the limestone cavities area, high pressure jet grouting has been carried out as a countermeasure method. Despite the fact that high pressure jet grouting method has already adopted at a lot of limestone cavities area, but the amount of research and technical data on the high pressure jet grouting have not been accumulated properly so for. Therefore this paper intends to investigate the strength characteristics and deformation characteristics for reinforced limestone cavities area by high pressure jet grouting method. In addition, load carrying capacity obtained by static pile load test with load transfer measuring system is analyzed.

• The Journal of Engineering Geology
• /
• v.27 no.4
• /
• pp.501-511
• /
• 2017

Natural radionuclides such as uranium and radon from 170 groundwater wells in Jeonnam Province were investigated, together with hydrogeochemical properties, and concentration maps of uranium and radon were also constructed in this study. Characteristics of their concentrations and occurrence were discussed using hydrogeochemical factors and geostatistical methods based on individual geological units. Though uranium and radon in groundwater show a wide range in the concentration, most of which occur as low levels except a few sites. Based on factor analysis, correlation coefficients between uranium and radon are very low. Such results verify that these radionuclides behave independently, well consistent with most previous results investigated nationwide in groundwater. Besides uranium and radon, most hydrochemical components in groundwater show a close relation to indicate the water-rock interaction taken place actively in aquifer.

• The Journal of Engineering Geology
• /
• v.22 no.3
• /
• pp.353-363
• /
• 2012

The geology of Ulleung-Do is dominated by volcanic rocks with low strength and trachytic rocks with high strength but containing vertical joints that yield easily. Consequently, rockfalls along roadcuts are a major geological hazard, with the potential to affect the ring road of Ulleung-Do. In this study, we performed three types of rockfall hazard-risk assessment on the 3-km-long section of the ring road expected to have the highest possibility of rockfall. We used a rockfall ranking sheet in a roadside landslide hazard map, the Slope Stability Inspection Manual for National Highways (Japan), and a rockfall hazard rating system for inspection from the Japan Highway Public Corporation. We also employed the evaluation criteria of 'RHRS' developed by the Federal Highway Administration (FHA). An analysis of roadcuts at 27 sites with regard to geographic and geological conditions resulted in the identification of three classes of rockfall hazard (high, medium, and low). Of note, over 74% of slopes were assessed as high- and medium-class. Finally, a rockfall hazard map of the northeast region of Ulleung-Do was produced based on the evaluation results.

• The Journal of Engineering Geology
• /
• v.16 no.3 s.49
• /
• pp.283-291
• /
• 2006

Shotcrete is used as a permanent lining in single shell tunnels even though shotcrete has been used as a temporary lining in NATM tunnels. Therefore, the accurate evaluation of strength parameters is very crucial because the reliable estimation of loads acting on the shotcretes is necessary to maintain the stability of tunnels. The evaluation of strength parameters of the ground far the single shell tunnels should be investigated to adapt the method in Korea because the geological condition of Korea is different from that of other country. Rock classification and strength parameters obtained from 25 tunnel sites were investigated for this study. Support types fur the different rock classes are suggested for the single shell tunnels in Korea based on the NMT because Q-system has been widely used in Korea. The support types in terms of both Q and RMR values are given based on the correlation of Q and RMR values obtained from the case studies.

• The Journal of Engineering Geology
• /
• v.8 no.1
• /
• pp.13-23
• /
• 1998

An intensity of the 1997 Kyungju earthquake(M=4.3) was estimated at three hundred locations based on the field survey and questionaires from 2200 residents. The isoseismal shows almost circular pattern which doesnot reflect some specific geological trends. However,most of the Kyeongsang basin except the southwestern part is included within the area of MM intensity V. There occurred strong shaking, numerous cracks on the wall of the houses, and movement of slate on the roofs, falling of the tiles from the monument. The isoseismal of the highest MM intensity VII, 1-3 km in width and 9 km in length, is elongated along the Yangsan fault, which is located about 1.5 km west from epicenter. The lineaments near the epicenter exhibit almost N-S and NNE directions. The lineament distribution, the pattern of damage area and the solution of fault plane suggest that the Kyongju earthquake occurred with strike-slip sense along the Yangsan fault. The calculated intensity attenuation(I) with distance(R) is as follows : $I{\;}={\;}I_o{\;}+{\;}0.3461{\;}-{\;}0.3274{\;}{\times}{\;}1nR{\;}-{\;}0.086{\;}{\times}{\;}R$.

• The Journal of Engineering Geology
• /
• v.17 no.4
• /
• pp.555-566
• /
• 2007

In general, RMR classification system is used for the support design of a tunnel. Face mapping during excavation and RMR-based rock classifications are conducted in order to provide information for complementary changes to preliminary survey plans and for continuous geological estimations in direction of tunnel route. Although they are ever so important, there are not enough time for survey in general and sometimes even face mapping is not available. Linear regression analysis for the estimation of mediating RQD and condition of discontinuities, which require longer time and more detailed observation in RMR, was performed and optimum regression equations are suggest as the result. The geological data collected from tunnels were analyzed in accordance with three rock types as sedimentary rock, phyllite and granite to see geological effects, generally not been considered in previous researches. Parameters for the regression analysis were set another RMR factor.

• The Journal of Engineering Geology
• /
• v.12 no.4
• /
• pp.395-404
• /
• 2002

Contents of the specific components in the natural mineral water was discussed in relation to the well depth and geology. According to water quality data during the last five years(1998~2002), the nitrate and fluoride concentrations, and pH averaged 0.89~ 1.09 mg/L, 0.37~0.45 mg/L, and 7.30~7.59, respectively. These values are the similar range to those of generalized groundwater having same well depths, implying that shallow groundwaters flow into the production wells. In general, no clear relationships between the water quality, well depth, and geology were found. The average arsenic concentration of the natural mineral water increased from 0.0024 mg/L in 1999 to 0.0066 mg/L in 2002. The percentage of production well with arsenic level higher than 0.001 mg/L also increased from 20.1% in 1999 to 64.9% in 2002. In 2002, 11 out of 57 production wells exceed 0.001 mg/L which will be announced as a new arsenic standard for drinking water by USEPA.