• Journal of the Korean Geotechnical Society
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• v.20 no.8
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• pp.15-27
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• 2004

Sliding aspects of rock slope, where large-scaled tension cracks are induced during preliminary excavation, have been analyzed. Structure of rock mass is investigated by performing the electrical resistivity survey and the orientations and positions of discontinuities are measured from DOM-drilled core log. Geological evidence far primary failure movement has been detected and clay minerals which possess swelling properties are identified through XRD analysis. Slope stability is examined by considering the orientations of discontinuities and their trace distributions on the cut-face and neighboring natural slope surface. Both orientations and positions of failure-invoking discontinuity planes, traces of which are exposed within the anticipated sliding region, are concerned fur analyzing the preferred sliding directions. Regional sliding vectors are assessed based on the relative positions of potential sliding planes in the boreholes and the general trend of anticipated failure movement of rock slope is also investigated.

• Journal of Korean Society of Forest Science
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• v.108 no.2
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• pp.233-240
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• 2019

The aim of this study was to provide basic data that could identify and help prevent a slow-moving landslide using an analysis of the relationship between below-ground characteristics and water from three slow-moving landslide areas in Pohang, Gyeongsangbuk-do, South Korea. Surface surveys, resistivity, seismic exploration, well logging, and boring surveys were conducted in the three areas. The main direction of discontinuous surface was matched with the slope direction of the three landslides. The results indicatedthat slow-moving landslides might occur in the direction of the slope. Underground water was distributed within the crush zones within the three landslide areas and flowed along the tensile cracks. There was a significant difference (p<0.01) between the mean angle of the tensile cracks and that of the underground waterflow (p=0.8019). These results indicated that the progress of a slow-moving landslide can be forecast by monitoring the location and flow of underground water within a known slow-moving landslide area.

• Journal of the Korean Geotechnical Society
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• v.25 no.12
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• pp.27-35
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• 2009

KICT (Korea Institute of Construction and Technology) and KISTEC (Korea Infrastructure Safety and Technology Corporation) have been carrying out inventory survey on cut slopes along national roads since 2006. Unlike precision safety check, cut slope inventory survey is a simple check about cut slope's characteristics with the naked eye to collect the data base of slope maintenance. Inventory survey is classified into general status, cut slope characteristics and inspector opinions. The inventory data are analyzed to identify dangerous slopes and decide a safety ranking. In this paper, we performed a correlation analysis using SPSS (ver.15) about the 10,461 cut slope inventory data which are collected in Kangwondo and Chungcheongdo from 2006 to 2008. We calculated the correlation coefficient between cut slope inventory data and the danger score derived from the data. And we evaluated cut slope inventory data which have the more influence on the danger degree of cut slope. According to results of correlation analysis, we found that inventory data influencing cut slope danger degree are stuck and fallen rock, orientation of discontinuity and angle of upper slope. And these data are slightly different by regionally. Later on, if inventory research is finished, we will understand regional characteristics of cut slopes.

• Geotechnical Engineering
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• v.14 no.5
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• pp.53-66
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• 1998

Since weathered soils are made by weathering process, the characteristics of weathered soils are strongly related to the originated rock and its forming process. Investigations on the originated rock and the weathering environments that decide the forming process are indispensable for the appropriate analysis on weathered soils. In this study, forming process of weathered soil is investigated by geological viewpoint. Test results show that weathering of rock is closely related to the distribution of rock-forming mineral and forming process. Weathered granite soils have the isotropic in-situ stress state and shearing behavior caused by the non-directional characteristics of originated rock. And weathered gneiss soils have the directional characteristics that mechanical behavior is determined by internal discontinuities. It it proved that the weathering resistance of Quarte is greater than that of feldspar and mica, and it is concluded that the thickness of weathered region is greatly influenced by the distribution of rock-forming mineral.

• Tunnel and Underground Space
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• v.10 no.2
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• pp.165-172
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• 2000

When tunnels or underground structures are constructed in anisotropic rock mass, designers and constructors have to consider the anisotropic characteristics in rock mass because their physical and mechanical properties are depended on the anisotropic angles(${\beta}$). In this study, therefore, we have first investigated the mechanical behavior of the gneiss specimen from lab. tests, and then have analysed the behavior of specimens for to the transversely isotropic model in elastic medium using the FLAC program. The results of this study were summarized as follows; 1) In the result of the variation tests, in general, the properties of strength were depended on the angle of inclination in spite of the hard rock. And except for the shear strength test, the lowest and peak stress were appeared at 60$^{\circ}$ and 90$^{\circ}$respectively. 2) The results of specimen modeling analysis using FDM well indicated the mechanical behaviors of the specimen of transversely isotropic model.

• The Journal of Engineering Geology
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• v.17 no.2 s.52
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• pp.309-315
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• 2007

The purpose of this paper is to make a close inquiry into the relationship between width and length of crack as a method to maximize compensation effect by grouting discontinuity within weak bedrock, together with emphasis on application of the basic data to the reformation of weak bedrock in a construction site. The result reveals that the length of trace at each fracture averages $1.5{\sim}3.0mm$. Based on analysis of openness distribution pattern at each fracture, the estimated values are quite well in agreement with those of the experiment, with a negative trend in the distribution of aperture width.

• The Journal of Engineering Geology
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• v.19 no.2
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• pp.119-129
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• 2009

In relation to slope stability analysis, geologic characteristics and engineering properties of the discontinuities in three slopes selected are compared and analyzed by both square-inventory method and scanline survey. The aim of the study is in evaluating which method is applied better in slope stability analysis by comparing results of the two methods with those of direct observation on outcrop of slope failures generated. In each slope, results of comparative analysis among geologic and engineering properties are analyzed similarly one another. However, results of orientation analysis in slope 2 are different each other, which indicates orientation of joints in slope 2 depends on persistency and frequency of each joint and also indicates appearance of new joint set with different orientation. Probability density distribution and spacing in slope 3 are high in comparison to those in slope 2 and 3. The reasons are that distribution of psammitic rocks and development of minor folds in slope 3 unlike slope 2 and 3 are closely associated with development of joints. The research data indicate that the square-inventory method predicts more precise failure aspects and is more effective way than scanline survey in analyzing slope stability of the study area.

• Journal of Korean Tunnelling and Underground Space Association
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• v.18 no.2
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• pp.235-244
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• 2016

Grouting is frequently used before the construction of subsea tunnels to mitigate problems that can occur in weak ground zones such as joints, faults or unconsolidated settlements during construction. The grout material injected into rock mass often flows through the discontinuities present in the host rock and hence, joint properties such as its distribution, roughness and thickness greatly affect the properties of grouting-improved rocks. The grouting-improved zones near subsea tunnels are also subjected to high water pressures that can cause long-term weathering in the form of changes in grout microstructure and crack formation and lead to subsequent changes in ground properties. Therefore, an assessment method is needed to accurately measure changes in the grouting-improved zones near subsea tunnels. In this study, the elastic wave propagation characteristics in grouting-improved rocks were tested for various axial stress levels, curing time, joint roughness and thickness conditions under laboratory conditions and the results were compared with wave velocity standards in different Korean rock mass classification systems to provide a basis for inferring improvement in grouted rock-mass.

• Economic and Environmental Geology
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• v.55 no.1
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• pp.1-17
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• 2022

The mechanical and thermal properties of the rock masses can affect the performance associated with both the isolating and retarding capacities of radioactive materials within the deep geological disposal system for High-Level Radioactive Waste (HLW). In this study, the essential parameters for the site descriptive model (SDM) related to the rock mechanics and thermal properties of the HLW disposal facilities site were reviewed, and the technical background was explored through the cases of the preceding site descriptive models developed by SKB (Swedish Nuclear and Fuel Management Company), Sweden and Posiva, Finland. SKB and Posiva studied parameters essential for the investigation and evaluation of mechanical and thermal properties, and derived a rock mechanics site descriptive model for safety evaluation and construction of the HLW disposal facilities. The rock mechanics SDM includes the results obtained from investigation and evaluation of the strength and deformability of intact rocks, fractures, and fractured rock masses, as well as the geometry of large-scaled deformation zones, the small-scaled fracture network system, thermal properties of rocks, and the in situ stress distribution of the disposal site. In addition, the site descriptive model should provide the sensitivity analysis results for the input parameters, and present the results obtained from evaluation of uncertainty.

• The Journal of Engineering Geology
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• v.22 no.1
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• pp.59-65
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• 2012

The purpose of this study is to analyze the direction of slope sliding that occurred at the highland ${\bigcirc}{\bigcirc}$ district in the Samcheok coalfield, using geological and structural detail surveys. The study area is dominated by the Paleozoic Pyong-an Group, and sliding is concentrated in zones of alternating sandstone and shale beds in the Geumcheon and Jangsung Formations. Discontinuities in the area have a strike of NE-SW and dip at 30~$80^{\circ}$ to the NW and 40~$80^{\circ}$ to the SE. However, some have strikes of NW-SE. In slide area group 1 (P1 to P4), en echelon tension gashes were caused by shearing. The surface in the areas of group 2 (P5 to P7) and group 3 (P8 and P9) is marked by step-type tension cracks that formed due to extension. This phenomenon caused anticlockwise rotation of the sliding slope. Otherwise, the cutting of the road side through the eastern slope of the mountain contributed to surface sliding due to geographical equilibrium loss.