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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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The Journal of Engineering Geology
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Journal DOI :
The Korea Society of Engineering Gelolgy
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Volume & Issues
Volume 26, Issue 2 - Jun 2016
Volume 26, Issue 1 - Mar 2016
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Estimations of Regional Stress Based on Measured Local Stress
Obara, Yuzo ; Kaneko, Katsuhiko ; Kang, Seong-Seung ;
The Journal of Engineering Geology, volume 26, issue 2, 2016, Pages 169~175
DOI : 10.9720/kseg.2016.2.169
Estimations of regional stress are demonstrated in this paper. Firstly, regional stress is defined and the characteristics of regional stress are then discussed based on the local stresses measured by the Compact Conical-ended Borehole Overcoring (CCBO) technique and the results from the earthquake focal mechanism. Secondly, the regional stresses are estimated by a back analysis of three-dimensional finite element models, using the local stresses measured by the CCBO and hydraulic fracturing.
A Feasibility Study of Earthquake Monitoring Using a High-resolution Borehole Strainmeter
Soh, Inho ; Chang, Chandong ;
The Journal of Engineering Geology, volume 26, issue 2, 2016, Pages 177~185
DOI : 10.9720/kseg.2016.2.177
This work investigates whether stress changes induced by an earthquake can be estimated using the deformation measured by high-resolution borehole strainmeters. We estimate the changes in the orientation and magnitude of the principal compression stresses using borehole strainmeter data recorded before and after the M7.2 El Mayor-Cucapah earthquake on April 4, 2010. Clear differences in the stress orientations and magnitudes are apparent before and after the event. The change in stress orientation appears related to subtle increases of stress in the tectonic maximum principal orientation, which is in agreement with the earthquake focal mechanism solution. The sudden stress drop at the onset of the earthquake was 10
MPa in the principal orientations. The Coulomb stress transfer model, which can estimate stress transfer, predicts a shear stress increase of (0.1-0.6) × 10
MPa at the strainmeter site, which is in line with the measured data (0.3-0.8) × 10
MPa. Overall, our results suggest that borehole strainmeter data reflect the subtle stress changes associated with earthquake occurrence, and that such data can be utilized for earthquake-related research.
Prediction of Fault Zone ahead of Tunnel Face Using Longitudinal Displacement Measured on Tunnel Face
Song, Gyu-Jin ; Yun, Hyun-Seok ; Seo, Yong-Seok ;
The Journal of Engineering Geology, volume 26, issue 2, 2016, Pages 187~196
DOI : 10.9720/kseg.2016.2.187
We conducted three-dimensional finite element analysis to predict the presence of upcoming fault zones during tunneling. The analysis considered longitudinal displacements measured at tunnel face, and used 28 numerical models with various fault attitudes. The x-MR (moving range) control chart was used to analyze quantitatively the effects of faults distributed ahead of the tunnel face, given the occurrence of a longitudinal displacement. The numerical models with fault were classified as fault gouge, fault breccia, and fault damage zones. The width of fault cores was set to 1 m (fault gouge 0.5 m and fault breccia 0.5 m) and the width of fault damage zones was set to 2 m. The results, suggest that fault centers could be predicted at 2~26 m ahead of the tunnel face and that faults could be predicted earliest in the 45° dip model. In addition, faults could be predicted earliest when the angle between the direction of tunnel advance and the strike of the fault was smallest.
Proposed Landslide Warning System Based on Real-time Rainfall Data
Kim, Hong Gyun ; Park, Sung Wook ; Yeo, Kang Dong ; Lee, Moon Se ; Park, Hyuck Jin ; Lee, Jung Hyun ; Hong, Sung Jin ;
The Journal of Engineering Geology, volume 26, issue 2, 2016, Pages 197~205
DOI : 10.9720/kseg.2016.2.197
Rainfall-induced landslide disaster case histories are typically required to establish critical lines based on the decrease coefficient for judging the likelihood of slope collapse or failure; however, reliably setting critical lines is difficult because the number of nationwide disaster case histories is insufficient and not well distributed across the region. In this study, we propose a method for setting the critical area to judge the risk of slope collapse without disaster case history information. Past 10 years rainfall data based on decrease coefficient are plotted as points, and a reference line is established by connecting the outermost points. When realtime working rainfall cross the reference line, warning system is operating and this system can be utilized nationwide through setting of reference line for each AWS (Automatic Weather Station). Warnings were effectively predicted at 10 of the sites, and warnings could have been issued 30 min prior to the landslide movement at eight of the sites. These results indicate a reliability of about 67%. To more fully utilize this model, it is necessary to establish nationwide rainfall databases and conduct further studies to develop regional critical areas for landslide disaster prevention.
Potential Hazard Classification of Aged Cored Fill Dams
Park, DongSoon ; Oh, Je-Heon ;
The Journal of Engineering Geology, volume 26, issue 2, 2016, Pages 207~221
DOI : 10.9720/kseg.2016.2.207
As greater numbers of fill dams and reservoirs become old, the risks of damage or embankment collapse increases. However, few studies have considered the deterioration and hazard classification of the internal core layers of fill dams. This study reports the results of geotechnical investigations of 13 earth-cored fill dams in Korea, based on no-water borehole drilling, Standard Penetration Test, and 2D and 3D electrical resistivity surveys along with in situ and laboratory testing. High-capacity no-water boring minimized core layer disturbance while providing continuous core sample recovery. The results allow the classification of potential hazards related to the existing core layers based on both visual inspection of the recovered samples and the results of engineering surveys and tests. Four types of potential hazard are classified: locally fluidized core with a high water content, rapid water inflow to a borehole, cores with granular materials, and relatively low stiffness of core. Among these, the locally fluidized core is the most critical hazard that requires remedial action because it is related to the potential internal flow path and internal erosion. The other three hazard types are of medium importance and require careful monitoring and regular inspection. Of note, there was no correlation between age and core deterioration. The results are expected to aid the safe management and potential upgrading of aging cored fill dams.
Business Ecosystem-focused Commercialization Strategy for Real-time Monitoring and Detection Technology for Landslides
Sawng, Yeong-Wha ; Lim, Dong-Hyun ; Chae, Byung-Gon ; Choi, Junghae ;
The Journal of Engineering Geology, volume 26, issue 2, 2016, Pages 223~233
DOI : 10.9720/kseg.2016.2.223
This study establishes a commercialization strategy for technology that can monitor and detect landslides in real time. An effective commercialization strategy was sought through both qualitative and quantitative analyses. The qualitative analysis considered the business environment in detail, while the quantitative analysis examined technologically strong and weak areas by visualizing the links between IPC (International Patent Classification) code structure and patent applicants. The results from both analyses are considered together, with particular attention paid to the business environment. The resulting integrated analysis comprehensively explores the degree of technological development and the current state of real-time monitoring and detection technology for landslides. The integrated analysis identified complementary assets in the business environment, as there is strong development and many research entities in this area. This suggests positive reinforcement for commercialization with two sub-strategies: (1) exploring demand with complementary assets, and (2) providing technology information for explored demand, which should facilitate successful commercialization. Exploiting this positive reinforcement for technology commercialization could reduce the high uncertainty of the technology and the market, and thus increase the probability of successful commercialization. It is also expected to contribute to long-term success by strengthening collaboration between the supply and demand sides.
A Feasibility Study of a Rainfall Triggeirng Index Model to Warn Landslides in Korea
Chae, Byung-Gon ; Choi, Junghae ; Jeong, Hae Keun ;
The Journal of Engineering Geology, volume 26, issue 2, 2016, Pages 235~250
DOI : 10.9720/kseg.2016.2.235
In Korea, 70% of the annual rainfall falls in summer, and the number of days of extreme rainfall (over 200 mm) is increasing over time. Because rainfall is the most important trigger of landslides, it is necessary to decide a rainfall threshold for landslide warning and to develop a landslide warning model. This study selected 12 study areas that contained landslides with exactly known triggering times and locations, and also rainfall data. The feasibility of applying a Rainfall Triggering Index (RTI) to Korea is analyzed, and three RTI models that consider different time units for rainfall intensity are compared. The analyses show that the 60-minute RTI model failed to predict landslides in three of the study areas, while both the 30- and 10-minute RTI models gave successful predictions for all of the study areas. Each RTI model showed different mean response times to landslide warning: 4.04 hours in the 60-minute RTI model, 6.08 hours in the 30-minute RTI model, and 9.15 hours in the 10-minute RTI model. Longer response times to landslides were possible using models that considered rainfall intensity for shorter periods of time. Considering the large variations in rainfall intensity that may occur within short periods in Korea, it is possible to increase the accuracy of prediction, and thereby improve the early warning of landslides, using a RTI model that considers rainfall intensity for periods of less than 1 hour.
Analysis of the Effects of Drainage Systems in Wetlands Based on Changes in Groundwater Level, Soil Moisture Content, and Water Quality
Kim, Chang-Hoon ; Ryu, Jeong-Ah ; Kim, Deog-Geun ; Kim, Gyoo-Bum ;
The Journal of Engineering Geology, volume 26, issue 2, 2016, Pages 251~260
DOI : 10.9720/kseg.2016.2.251
Groundwater flow due to hydraulic gradients across a geologic barrier surrounding a dam reservoir can cause swamps or wetlands to form on the downstream side of the dam, thereby restricting land use. The difference in head between the reservoir level and the downstream groundwater level creates a hydraulic gradient, allowing water to flow through the geologic barrier. We constructed a drainage system at the Daecheong dam to study the effects on groundwater levels and soil moisture contents. The drainage system consisted of a buried screened pipe spanning a depth of 1-1.5 m below a land surface. Groundwater levels were monitored at several monitoring wells before and after the drainage system was installed. Most well sites recorded a decline in groundwater level on the order of 1 m. The high-elevated site (monitoring well W1) close to the reservoir showed a significant decline in groundwater level of more than 2 m, likely due to rapid discharge by the drainage system. Soil moisture contents were also analyzed and found to have decreased after the installation of the drainage system, even considering standard deviations in the soil moisture contents. We conclude that the drainage system effectively lowered groundwater levels on the downstream side of the dam. Furthermore, we emphasize that water seepage analyses are critical to embankment dam design and construction, especially in areas where downstream land use is of interest.
Occurrence Characteristics of Uranium and Radon-222 in Groundwater at ○○ Village, Yongin Area
Jeong, Chan Ho ; Yang, Jae Ha ; Lee, Yong Cheon ; Lee, Yu Jin ; Cho, Hyeon Young ; Kim, Moon Su ; Kim, Hyun Koo ; Kim, Tae Seong ; Jo, Byung Uk ;
The Journal of Engineering Geology, volume 26, issue 2, 2016, Pages 261~276
DOI : 10.9720/kseg.2016.2.261
The occurrence of natural radioactive materials such as uranium and radon-222 in groundwater was examined with hydrogeochemistry and geology at ○○ village in the Yongin area. Two rounds of 19 groundwater and 5 surface water sampling were collected for analysis. The range of pH value in groundwaters was 5.81 to 7.79 and the geochemical types of the groundwater were mostly Ca(Na)-HCO
. Uranium and radon-222 concentrations in the groundwater ranged from 0.06 to 411 μg/L and from 5.56 to 903 Bq/L, respectively. Two deep groundwaters used as common potable well-water sources exceeded the maximum contaminant levels of the uranium and radon-222 proposed by the United States Environmental Protection Agency (US EPA). Three groundwater samples from residential areas contained unsuitable levels of uranium, and 12 groundwater samples were unsuitable due to radon-222 concentrations. Radioactive materials in the unsuitable groundwater are naturally occurring in a Jurassic amphibole- and biotite-bearing granitic gneiss. High uranium and radon-222 groundwater concentrations were only observed in two common wells; the others showed no relationship between bedrock geology and groundwater geochemical constituents. With such high concentrations of naturally occurring radioactive materials in groundwater, the affected areas may extend tens of meters for uranium and even farther for radon-222. Therefore, we suggest the radon-222 and the uranium did not originate from the same source. Based on the distribution of radon-222 in the study area, zones of higher radon-222 concentrations may be the result of diffusion through cracks, joint, or faults. Surface radioactivity and uranium concentrations in the groundwater show a positive relationship, and the impact areas may extend for ~200m beyond the well in the case of wells containing high concentrations of uranium. The highest uranium and thorium concentrations in rock samples were detected in thorite and monazite.
Constructing Geological Cross-sections at Depth and Interpreting Faults Based on Limited Shallow Depth Data Analysis and Core Logging: Southern Section of the Yangsan Fault System, SE Korea
Kim, Taehyung ; Kim, Young-Seog ; Lee, Youngmin ; Choi, Jin-Hyuck ;
The Journal of Engineering Geology, volume 26, issue 2, 2016, Pages 277~290
DOI : 10.9720/kseg.2016.2.277
Deep geological cross-sectional data is generally not common nor easy to construct, because it is expensive and requires a great deal of time. As a result, geological interpretations at depth are limited. Many scientists attempt to construct geological cross-sections at depth using geological surface data and geophysical data. In this paper, we suggest a method for constructing cross-sections from limited geological surface data in a target area. The reason for this study is to construct and interpret geological cros-sections at depth to evaluate heat flow anomaly along the Yangsan fault. The Yangsan Fault passes through the south-eastern part of the Korean Peninsula. The cross-section is constructed from Sangbukmyeon to Unchonmyeon passing perpendicularly through the Yangsan Fault System trending NW-SE direction. The geological cross-section is constructed using the following data: (1) Lithologic distributions and main structural elements. (2) Extensity of sedimentary rock and igneous rock, from field mapping. (3) Fault dimension calculated based on geometry of exposed surface rupture, and (4) Seismic and core logging data. The Yangsan Fault System is composed of the Jain fault, Milyang fault, Moryang fault, Yangsan fault, Dongnae fault, and Ingwang fault which strike NNE-SSW. According to field observation, the western section of the Yangsan fault bounded by igneous rocks and in the eastern section sedimentary rocks are dominant. Using surface fault length we infer that the Yangsan Fault System has developed to a depth of kilometers beneath the surface. According to seismic data, sedimentary rocks that are adjacent to the Yangsan fault are thin and getting thicker towards the east of the section. In this study we also suggest a new method to recognize faults using core loggings. This analysis could be used to estimate fault locations at different scales.