• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.2
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• pp.1089-1095
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• 2014

In this study, we compared and analyzed the displacement of final excavation with measured value through an inverse analysis method used in urban excavation construction. We maximized the effectiveness of the inverse analysis method, and plan to achieve cost-effective and practical construction management in the field with identical conditions. As the first stage, we suggest an example of a field which has the inverse analysis method. We applied the inverse analysis method to three different fields on which construction and measuring were finished. Of these three fields, two fields showed a very satisfactory result. However, in one field, there were significant differences between the analysis and measured value. The result of our analysis indicated that, we should unite the conditions of the inverse analysis method and field construction. We need to thoughtfully reconsider the RANKINE earth pressure application in a triangle type. This is because the uniformity of earth pressure is made by its arching effect, in the condition of the displacement of lower underground occurring widely, which is differentiated with the earth pressure conditions of RANKINE, even if the slurry wall has stiffness. Also, when recalculating the soil parameter, we should emphasize the adhesion of the weathering zone, and give experimental consideration to ground water level.

• Tunnel and Underground Space
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• v.17 no.3 s.68
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• pp.175-185
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• 2007

When filling material such as clay is included along the discontinuity, it may cause instability on a slope even if the direction of discontinuity works in a positive way. In the study area, slope sliding occurred at the boundary between a clay filling material and weathered soil because the physical properties differ across the boundary; and this is very similar to the situation where foliation in a rock works as a weak zone during a structural behavior, causing an inter-layer slip. In most analysis, if there exists a clay filling material, a single discontinuity is assumed to perform analysis. In those cases, the discontinuity is modeled as a slip surface within clay. Therefore, the characteristics of the boundary are not considered in the analysis, so that ultimately the physical property of clay usually prevails. The result of evaluating the slope stability affected by clay filling material shows the significant difference in the safety level due to the strength parameter depending on the failure type of the discontinuity by a filling material.

• Tunnel and Underground Space
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• v.17 no.2 s.67
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• pp.83-89
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• 2007

Impact-echo test is a non-destructive testing method to determine dynamic properties of a material. This presentation introduces the experimental set-up and procedure of the test for rock specimens. In addition, the test results of domestic rocks collected in 5 different areas, a cement mortar and aluminium alloy are presented. The test results include resonance frequencies of P- and S-wave as well as damping ratios of the described 7 different materials. The differences between dynamic and static values of elastic moduli are about 10%, while the dynamic Poisson's ratios are greater than the static Poisson's ratios by at least 0.07. The damping ratio is dependent on the joint density and degree of weathering of a rock specimen.

• Journal of The Geomorphological Association of Korea
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• v.19 no.3
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• pp.83-96
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• 2012

The origins of beaches at Byeonsan Peninsular, as a pocket type, are classified to a sand barrier type and wave-cut type. The beaches had developed by the deposition of the silt and clay layers on the 10m height from sea level in the inner bay during climax era of postglacial transgression. At that time, some sands had blown toward the inland hills to form aeolian deposits. After postglacial sea-level stabilization, sometimes, there has been the negative budget of beach materials. Recently, beaches have been transformed by human impact such as construction of Saemangeum sea-wall, especially in the Byeonsan and Gosapo beaches being close to the sea-wall. So the speed of tidal currents become slower and comparatively depositoinal activity stronger. And the level of chemical weathering has been higher. In Byeonsan beach, the ratio of coarse sand decreased with higher ratio of finer materials and by beach erosion dissected runnels developed, running parallel to the coastline. In Gosapo beach, supply of suspended materials are increased through the Garyeok drainage gate, the sands tend to be finer.

• Journal of the Korean GEO-environmental Society
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• v.20 no.1
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• pp.35-42
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• 2019

Various development works inevitably increase cutting slopes due to land use, and many of trails managed by different authorities are being deteriorated by long-term weathering. Collapse of slopes causes unavoidable damage of property and loss of lives because of its uncertainty and difficulty in predicting its occurrence. In order to overcome the unavoidability, America, Japan, and several European nations analyze the kinetic energy and moving distance when rocks of upper slope move along the inclined plane, via field tests and computerized interpretation of the test results. Also, they are making efforts to develop measures with which the kinetic energy of the rocks moving along the slope is absorbed and fails to reach to specific structures. However, domestic researches just focus on fragmentary prediction of rockfall using existing programs, and there have been few approaches to identify interpretation methods appropriate for domestic cases or determination of parameters. In this context, we in this study defined rockfall types and affecting factors and analyzed effects of parameters using a general-purpose rockfall simulation program to understand principles of rockfall and to estimate effects of various parameters.

• Economic and Environmental Geology
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• v.54 no.1
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• pp.137-150
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• 2021

The rock-carved standing Buddha triad in Seoak-dong is a large stone Buddha statue of the Unified Silla era (AD 676 to 935) in ancient Korea, built near the top of the southeastern side of mountain Seondosan in Gyeongju, is characterized by its locational importance, the powerful Amitabha and the gentle sculptural technique of the Bodhisattva. In particular, Amitabha Buddha in andesite rock slope with biotite granite pedestal and two Bodhisattva parallel made by alkali granites seems to express the dignity through the color and texture of the stones. In the Amitabha Buddha, deterioration characteristics are accelerating due to the combination of various joint systems, instability of the slopes and relaxation by the root pressure of plants occurring at the top. In addition, physical properties have deteriorated owing to the increase of discontinuous surfaces as joints, cracks and scalings, and the coverage of algae and lichen is also high. Therefore, deterioration degree in Buddha triad is accelerated due to the physical weathering characteristics from natural rock mass and various biological invasion.

• Journal of Korean Society of Disaster and Security
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• v.15 no.4
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• pp.79-86
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• 2022

The National Park Service is making efforts to create a safe environment by installing rockfall prevention facilities (rockfall prevention nets, fences, and Piam tunnels) in areas at risk of falling rocks. However, the occurrence of falling rocks is increasing every year due to torrential rains caused by climate change, abnormal temperatures in winter, and aging of the ground, and the need to improve the existing rock risk area management plan has emerged. In this study, a pilot area at risk of falling rocks was selected for the Hwanggol district of Chiaksan National Park among Korean national parks, and rockfall analysis was performed using the Rockfall program, and monitoring was conducted by applying a countermeasure method combined with the measurement system to the pilot area. Through this, a rockfall management plan was proposed for continuous management and monitoring of rockfall.

• Economic and Environmental Geology
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• v.35 no.4
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• pp.325-337
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• 2002

We examined the contamination of stream water and stream sediments by heavy metal elements with respect to distance from the abandoned Backun Au-Ag-Cu mine. High contents of heavy metals (Pb, Zn, Cu, Cd, Mn, and Fe) and aluminum in the waters connected with mining and associated deposits (dumps, tailings) reduce water quality. In the mining area, Ca and SO$_4$ are predominant cation and anion. The mining water is Ca-SO$_4$ type and is enriched in heavy metals resulted from the weathering of sulfide minerals. This mine drainage water is weakly acid or neutral (pH; 6.5-7.1) because of neutralizing effect by other alkali and alkaline earth elements. The effluent from the mine adit is also weakly acid or neutral, and contains elevated concentrations of most elements due to reactions with ore and gangue minerals in the deposit. The concentration of ions in the Backun mining water is high in the mine adit drainage water and steeply decreased award to down stream. Buffering process can be reasonably considered as a partial natural control of pollution, since the ion concentration becomes lower and the pH value becomes neutralized. In order to evaluate mobility and bioavailability of metals, sequential extraction was used for stream sediments into five operationally defined groups: exchangeable, bound to carbonates, bound to FeMn oxide, bound to organic matter, and residual. The residual fraction was the most abundant pool for Cu(2l-92%), Zn(28-89%) and Pb(23-94%). Almost sediments are low concentrated with Cd(2.7-52.8 mg/kg) than any other elements. But Cd dominate with non stable fraction (68-97%). Upper stream sediments are contaminated with Pb, and down area sediments are enriched with Zn. It is indicate high mobility of Zn and Cd.

• Journal of the Korean earth science society
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• v.39 no.2
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• pp.164-177
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• 2018

Even though various geological attractions are distributed domestically, the geological attractions are rarely utilized as field course site. The purpose of this study is to make Seonangbawi area as the field course site after geological investigations are carried out in detail. Seonangbawi is located about 1km southeast from Songjiho beach in Gangwon-do. Seonangbawi area is simply composed of Cretaceous Seokcho granite with the overlay of Quaternary alluvium. Geological field course in the Seonangbawi area will be useful to the student and citizen for developing the knowledge of geological phenomena, such as the formation of granite and minerals, and weathering process. In addition, the student and citizen can develop the knowledge of the geological structures, such as joint (N50E/80NW, N40W/84SW), fault (N42W/83SW), foliation (N32E/54SE), and dyke (N35E/40SE, N26W/63SW), and geographical features, such as tor, taforni, groove, and gnamma in the field. Accordingly, the Seonangbawi area is the best place to learn various geological and geographical phenomena and to discuss the origin of Seonangbawi with limited space.

• The Journal of the Petrological Society of Korea
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• v.16 no.2 s.48
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• pp.47-58
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• 2007

This study examines the distribution of basement rocks in Gyochon-ri, Muan-eup, Muan-gun, Jeonnam where ground subsidence occurred in June 2005, and traces corrosion of limestone. Mica schist and rhyolite are distributed in the surface of the study area, but thick limestone layer with large and small caverns are distributed underground. A horizon of limestone with maximum width of 300 m and 4 km of length was found along the detour which is in the north of pound subsidence. Such identification of limestone presence would be very useful to predict potential ground subsidence. Limestone in this area was disturbed by fold and fault due to severe shearing deformation. Small caverns were frequently found in anticline part of folds formed in limestone layer. Schists with different thicknesses were intercalated in the limestone with shearing deformation and consist of sheet silicate minerals (chlorite and mica) and quartz. In sections of weathered specimen, it is shown that biotite of schist part was altered into chlorite and corrosion of calcite around the schist followed. This suggest that ground water permeated between intercalated sheet silicate minerals and corrosion of limestone began. And small caverns were generated where active corrosion occurred. This study suggests that because of many reasons (for instance, reclamation of the Bulmu reservior and excess pumping), cavern water level was lowered and cave sediments were removed, and it caused ground subsidence to occur.