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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 23, Issue 4 - Dec 2013
Volume 23, Issue 3 - Sep 2013
Volume 23, Issue 2 - Jun 2013
Volume 23, Issue 1 - Mar 2013
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Estimation of Groundwater Table using Ground Penetration Radar (GPR) in a Sand Tank Model and at an Alluvial Field Site
Kim, Byung-Woo ; Kim, Hyoung-Soo ; Choi, Doo-Houng ; Koh, Yong-Kwon ;
The Journal of Engineering Geology, volume 23, issue 3, 2013, Pages 201~216
DOI : 10.9720/kseg.2013.3.201
Ground penetrating radar (GPR) surveys were conducted in a sand tank model in a laboratory and at an alluvial field site to detect the groundwater table and to investigate the influence of saturation on GPR response in the unsaturated zone. In the sand tank model, the groundwater table and saturation in the sand layer were altered by injecting water, which was then drained by a valve inserted into the bottom of the tank. GPR vertical reflection profile (VRP) data were obtained in the sand tank model for rising and lowering of the groundwater table to estimate the groundwater table and saturation. Results of the lab-scale model provide information on the sensitivity of GPR signals to changes in the water content and in the groundwater table. GPR wave velocities in the vadose zone are controlled mainly by variations in water content (increased travel time is interpreted as an increase in saturation). At the field site, VRP data were collected to a depth of 220 m to estimate the groundwater table at an alluvial site near the Nakdong river at Iryong-ri, Haman-gun, South Korea. Results of the field survey indicate that under saturated conditions, the first reflector of the GPR is indicative of the capillary fringe and not the actual groundwater table. To measure the groundwater table more accurately, we performed a GPR survey using the common mid-point (CMP) method in the vicinity of well-3, and sunk a well to check the groundwater table. The resultant CMP data revealed reflective events from the capillary fringe and groundwater table showing hyperbolic patterns. The normal moveout correction was applied to evaluate the velocity of the GPR, which improved the accuracy of saturation and groundwater table information at depth. The GPR results show that the saturation information, including the groundwater table, is useful in assessing the hydrogeologic properties of the vadose zone in the field.
Friction-dependent Slip Behavior of Imgok Fault under the Present-day Stress Field
Na, Hyun-Woo ; Chang, Chandong ; Chang, Chun-Joong ;
The Journal of Engineering Geology, volume 23, issue 3, 2013, Pages 217~225
DOI : 10.9720/kseg.2013.3.217
We carried out geometrical, kinematic, and geomechanical analyses on a lineament (the Imgok fault) near Gangneung, observed in ASTER images and aerial photographs, and field surveys. Earthquake focal mechanism solutions, used to estimate the present-day stress state, revealed that the direction of maximum compression is approximately N
E and that the stress condition is in favor of either strike-slip or reverse movement on the fault. The strike of the fault is not ideal for slip under the present-day stress field and thus the fault has a low slip tendency. However, the fault may be able to slip if the frictional coefficient (
), representing the resistance of the fault to slip, is sufficiently low (e.g.,
Forecasting and Assessment of the Grouting Effect, using a Numerical Model, to Prevent Groundwater Inflow during Excavation of a Vertical Shaft for a Selective Intake Structure
Kim, Gyoo-Bum ; Kim, Wan-Soo ; Park, Jung-Hoon ; Son, Yeong-Cheol ; Kim, Jin-Woo ;
The Journal of Engineering Geology, volume 23, issue 3, 2013, Pages 227~234
DOI : 10.9720/kseg.2013.3.227
The vertical shaft of a selective intake structure, which is constructed in a large reservoir, is required to be impermeable and to employ a grouting technology to prevent water inflow from the reservoir or surrounding ground. In this study, groundwater inflow is estimated using a numerical model for two cases (i.e., grouting or non-grouting cases at the exterior of a vertical shaft) and compared with data measured during an excavation at the construction site of a selective intake structure in the Soyang reservoir, Korea. Groundwater inflow is estimated to range from 444 to 754
in the case of non-grouting and from 58 to 95
in the case of grouting. The groundwater inflow measured in a vertical shaft, which ranges from 30 to 100
, is similar to the simulated amount. It is recommended that before the excavation of a shaft, water inflow is estimated using a numerical model and a grouting test to ensure excavation stability and improve excavation efficiency.
Analysis of Weathered State on a Halo Stone Buddha, Unju Temple of Hwasun, Korea Using Low Frequency Flaw Detector
Kang, Seong-Seung ; Ko, Chin-Surk ; Kim, Cheong-Bin ; Jang, Bo-An ;
The Journal of Engineering Geology, volume 23, issue 3, 2013, Pages 235~246
DOI : 10.9720/kseg.2013.3.235
P-wave velocity was measured by the low frequency flaw detector in order to analyze the weathered state of a halo stone Buddha, Unju temple, Hwasun, Korea. By the results of laboratory tests on a fresh acidic tuff with the same rock of a halo stone Buddha, average absorption, average P-wave velocity, and average uniaxial compressive strength were 5.38%, 4,008 m/s, and 70.1 MPa, respectively. The results correspond to moderately strong rock. Average P-wave velocity of a halo stone Buddha measured by the low frequency flaw detector was 2,257 m/s in the left zone, 3,437 m/s in the right zone, and 2,802 m/s overall. Weathering index of a halo stone Buddha was 0.45 in the left zone, 0.21 in the right zone, and 0.33 overall. Comparing the results of a halo stone Buddha with them of laboratory tests, weathered state of a halo stone Buddha was analyzed highly weathered state in the left zone and moderately weathered state in the right zone. Furthermore, it suggests that the left zone of a halo stone Buddha was affected weathering more than the right one. Overall a halo stone Buddha corresponds to moderately weathered state of weathering degrees. In conclusion, it is considered that low frequency flaw detector may be applicable as a valuable method on analyzing the P-wave velocity of the stone cultural heritage with an irregular surface.
Settlement Characteristics of a Large-Scale Foundation over a Sabkha Layer Consisting of Carbonate Sand
Kim, Seok-Ju ; Han, Heui-Soo ;
The Journal of Engineering Geology, volume 23, issue 3, 2013, Pages 247~256
DOI : 10.9720/kseg.2013.3.247
The carbonate sands of the Sabkha layer in the Middle East have very low shear strength. Therefore, instant settlement and time-dependent secondary settlement occur when inner voids are exposed, as in the case of particle crushing. We analyzed settlement of the Sabkha layer under a large-scale foundation by hydrotesting, and compared the field test results with the results of laboratory tests. With ongoing particle crushing, we observed the following stress-strain behaviors: strain-hardening (Sabkha GL-1.5 m), strain-perfect (Sabkha GL-7.0 m), and strain-softening (Sabkha GL-7.5 m). General shear failure occurred most frequently in dense sand and firm ground. Although the stress-strain behavior of Sabkha layer carbonate sand that of strain-softening, the particle crushing strength was low compared with the strain-hardening and strain-perfect behaviors. The stress-strain behaviors differ between carbonate sand and quartz sand. If the relative density of quartz sand is increased, the shear strength is also increased. Continuous secondary compression settlement occurred during the hydrotests, after the dissipation of porewater pressure. Particle crushing strength is relatively low in the Sabkha layer and its stress-strain behavior is strain-softening or strain-perfect. The particle crushing effect is dominant factor affecting foundation settlement in the Sabkha layer.
Analysis of Priority Investments for Preventing Roadside Slope Failures
Kim, Seung-Hyun ; Kim, Hong-Gyun ; Oak, Young-Suk ; Lee, Jong-Hyun ; Koo, Ho-Bon ;
The Journal of Engineering Geology, volume 23, issue 3, 2013, Pages 257~269
DOI : 10.9720/kseg.2013.3.257
Prevention plans for landslide and slope disasters should be appropriate for a country's budget when considering a systematic investment plan. The systematic management of slopes adjacent to national highways should incorporate reasonable investment risk and the expected degree of damage should be calculated by considering the investment priorities. In terms of priority of investment, the major factors used to determine the degree of hazard are gradient, soil characteristics, RMR (Rock Mass Rating), stability interpretation, type of discontinuities, and history of collapse, among others. The likely consequences of slope failure can be determined by considering traffic volume, the number of lanes, and average vehicle risk. We performed such calculations regarding the priority of investment and performed a regression analysis for 392 slopes located in Yeongseo region, Gangwon province. The calculation results show that collapsed slopes have a higher priority for investment, as do slopes with a high proportion of dangerous sections and locations in valleys.
CLSM Analysis of Change in Roughness and Physical Properties of Granite after Freeze-Thaw Experiments
Jeong, Jongtaek ; Choi, Junghae ; Chae, Byung-Gon ; Jang, Bo-An ;
The Journal of Engineering Geology, volume 23, issue 3, 2013, Pages 271~281
DOI : 10.9720/kseg.2013.3.271
Freeze-thaw experiments were conducted to evaluate changes in surface roughness and physical properties in samples of granite from Ilgwang and Imki mines, Korea. The temperature range in the experiments was
, based on typical summer and winter temperatures in Korea, and the surface was observed every 20 cycles. One cycle comprised 1 hour of heating or cooling of the samples and 1 hour during which the target temperature was maintained. With increasing repetitions of the freeze-thaw experiment, porosity increased by 0.05%-0.15% in the two samples and the dry weight increased, whereas the volume of the soil and saturation weight decreased. Observations by confocal laser scanning microscope (CLSM) revealed that line and surface roughness parameters showed a tendency to increase and decrease, respectively, with elapsed time. Changes in surface roughness were apparent on the CLSM images.
Analysis of the Stability and Behavior of a Calcareous Rock Slope During Construction of a Tunnel Entrance
Song, Young-Suk ; Yun, Jung-Mann ;
The Journal of Engineering Geology, volume 23, issue 3, 2013, Pages 283~292
DOI : 10.9720/kseg.2013.3.283
A calcareous rock slope failed during excavation of the slope for construction of a tunnel entrance. The slope is located at the construction site for widening highway in Yeongwol, Korea. Field surveys, laboratory tests, and numerical analyses were performed to determine the reason for the slope failure. The numerical analysis revealed that the safety factor of the slope before construction of the entrance was less than 1, and that this decreased after construction. After construction of the entrance, the sliding zone of the slope increased and slope stability decreased because the shear strain and plastic zone in the slope over the tunnel entrance showed an increase relative to the lower part of the slope. To enhance the stability of the slope for construction of the tunnel entrance, countermeasures such as rock bolts, rock anchors, and FRP (Fiber glass Reinforced Plastic) grouting were adopted in light of the field conditions. Serial field monitoring performed to confirm the reinforcing effects of the adopted countermeasures revealed a small amount of horizontal deformation of the slope soils, most of the elastic deformation that can regain its former value. In addition, the axial forces of the rock bolt and anchor were more strongly affected by slope excavation during construction of the tunnel entrance than by tunnel excavation or the rainy season, and the axial forces tended to converge after excavation of the tunnel. Therefore, we can confirm that the slope is currently safe.
A Study on Improving Installation Guideline of Facilities to Protect Groundwater Contamination: Applications of Packer Grouting to Contaminated Wells
Choo, Chang-Oh ; Ryu, Jong-Heum ; Cho, Heuy Nam ; Jeong, Gyo-Cheol ;
The Journal of Engineering Geology, volume 23, issue 3, 2013, Pages 293~304
DOI : 10.9720/kseg.2013.3.293
Because the present groundwater law broadly regulates a simple and impractical guideline ignoring aquifer characters and geology, general purpose facilities for protection of groundwater contamination is still considered unsatisfactory to ensure groundwater resources. In recent, there have been growing attempts in the packer development as crucial techniques and devices for groundwater protection. This study investigated the application of packer grouting techniques to contaminated groundwaters of two well sites in the Andong and Yeongi areas, both of which revealed a satisfactory effect with improved water quality: 94% decrease in turbidity at the Andong area and 60% decrease in
-N, respectively. Based on aquifer characters including geology, weathering depth, fracture pattern, hydraulic gradient, and the flow path of contaminants, the integrated properties of groundwater contamination should be evaluated and treated with the help of accurate analyses such as bore hole imaging and monitoring data. Packer grouting and casing on well to ensure the useful aquifer free of contaminant are expected to play important role in inhibiting the inflow of contaminants when adequately applied. Therefore it is concluded that these can serve as reliable tools in remediation and protection of contaminated groundwater as well as efficient utilization of groundwater.
Review of Research Trends on Landslide Hazards
Kim, J.H. ; Kim, W.Y. ;
The Journal of Engineering Geology, volume 23, issue 3, 2013, Pages 305~314
DOI : 10.9720/kseg.2013.3.305
Recent international and national research trends in landslide hazards were analyzed by performing a literature search of relevant scientific journals. For obtaining data from Korea, we used 'Information for Environmental Geology' (IEG), which covers 17 journals in the field of environmental geology. A total of 54 articles related to landslide hazards were found in 5 journals published in the period 2000-2012. The most common topic was landslide prediction or susceptibility (29 articles), followed by landslide mechanisms. For international information, we analyzed 1,851 articles from the 'Web Of Science' published from 2003 to the present. Researchers in Italy have published the greatest number of papers in this field, while papers from Korea rank first in terms of the citation index.