• The Journal of Engineering Geology
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• v.14 no.4 s.41
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• pp.429-442
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• 2004

Landslide of the Whanpyeong Mountain which was occurred at Busan Metropolitan City in 1999 belongs to the category of plane failure. Automatic monitoring system to measure horizontal displacement, pore pressure change and load change has operating from reconstruction stage for evaluating rock slope stability (August, 2000$\~$Feburuary, 2002). As a result of the analysis on the monitoring performance data, it is suggested that infiltrated rain water from pound surface discharges rapidly through cut-slope because pressure head of water decreases rapidly after rainfall while rise of pore pressure is proportional to the amount of rain water. As a result of data analyses for inclinometers and load cells, it seems that slope is stablized be cause ground deformation is rarely detected. The areas especially similar to the study site where landslide is induced by heavy rain fall, change of pore pressure is rapidly analyzed using automatic monitoring system. Therefore, it is considered that automatic monitoring system is very effect for slope stability analysis on important cut-slopes.

• The Journal of Engineering Geology
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• v.20 no.1
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• pp.13-23
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• 2010

Toppling failure of a slope is defined as failure behavior accompanying the rotation of rock block which is different from other failure such as sliding along with discontinuities and so on. It generally occurs in the region that discontinuities were developed with inverse dip direction to a slope and it could play a critical role in judging stability of slope. In this study, the stability evaluation was performed about toppling failure on a jointed road cut-slope. To check the deformation behavior, numerical analysis is widely used. However common analysis programs are based on continuum model. Recently, many methods that discontinuity properties can be considered in continuum analysis are suggested. In this study, numerical analysis based on FEM(Finite Element Method) was performed using interface element applied in heterogeneous boundary to simulate effects of discontinuities.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.1404-1414
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• 2008

In the mechanistic-empirical trackbed design of railways, the resilient modulus is the key input parameter. This study focused on the resilient modulus prediction model, which is the functions of mean effective principal stress and axial strain, for three types of railroad trackbed materials such as crushed stone, weathered soil, and crushed-rock soil mixture. The model is composed with the maximum Young's modulus and nonlinear values for higher strain in parallel with dynamic shear modulus. The maximum values is modeled by model parameters, $A_E$ and the power of mean effective principal stress, $n_E$. The nonlinear portion is represented by modified hyperbolic model, with the model parameters of reference strain, ${\varepsilon}_r$ and curvature coefficient, a. To assess the performance of the prediction models proposed herein, the elastic response of a test trackbed near PyeongTaek, Korea was evaluated using a 3-D nonlinear elastic computer program (GEOTRACK) and compared with measured elastic vertical displacement during the passages of freight and passenger trains. The material types of sub-ballasts are crushed stone and weathered granite soil, respectively. The calculated vertical displacements within the sub-ballasts are within the order of 0.6mm, and agree well with measured values with the reasonable margin. The prediction models are thus concluded to work properly in the preliminary investigation.

• Korean Journal of Remote Sensing
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• v.31 no.1
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• pp.29-38
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• 2015

The coastline influenced naturally and artificially changes dynamically. While the long-term change is influenced by the rise in the surface of the sea and the changes in water level of the rivers, the short-term change is influenced by the tide, earthquake and storm. Also, man-made thoughtless development such as construction of embankment and reclaimed land not considering erosion and deformation of coast has been causes for breaking functions of coast and damages on natural environment. In order to manage coastal environment and resources effectively, In this study is intended to analyze and predict erosion in coastal environment and changes in sedimentation quantitatively by detecting changes in coastal line from data collection for satellite images and aerial LiDAR data. The coastal line in 2007 and 2012 was extracted by manufacturing Digital Surface Model (DSM) with Aviation LiDAR materials. For the coastal line in 2009 and 2010, Normalized Difference Vegetation Index (NDVI) method was used to extract the KOMPSAT-2 image selected after considering tide level and wave height. The change rate of the coastal line is varied in line with the forms of the observation target but most of topography shows a tendency of being eroded as time goes by. Compared to the relatively monotonous beach of Taean, the gravel and rock has very complex form. Therefore, there are more errors in extraction of coastlines and the combination of transect and shoreline, which affect overall changes. Thus, we think the correction of the anomalies caused by these properties is required in the future research.

• Proceedings of the Korean Geotechical Society Conference
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• 1998.04a
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• pp.47-60
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• 1998

It is considered in this paper that the main causes of tunnel collapse during the construction were the insufficiency of data of geotechnical investigations, or their limits due to special ground condition such as its heterogeneity and anisotropy It is thought that safety of ground can be affected by the geological conditions such as presences of discontinuities in good intact rocks, and considered to be necessary that awareness of the conditions of discontinuities in advance is important to apply adequate reinforcement measures. It is also shown that a serious accident had occurred because of the unawareness of the permeable alluvial deposits at the top of the tunnel. And it is shown that the example of application of the results of geotechnical investigation such as face-mapping, pilot boring etc. during tunnel construction, and a serious deformation of tunnel under special geological condition. Therefore, it is strongly recommended to perform an adequate geotechnical investigation to confirm the geotechnical conditons of ground before design, and supplimentary investigation is also needed depending on conditions for safe and econonic construction.

• The Journal of Engineering Geology
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• v.18 no.2
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• pp.159-166
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• 2008

We have a question about the changing possibility of orientation of discontinuities through the depth of under-ground. To know this, the data from Honam coalfield composed of shale, sandstone and coal and Suwon area which crops out mica schist, were analyzed the discontinuities measured by BIPS and Televiewer. In Honam coalfield the orientations of joints are changed at 30-40 m depth of underground and in Suwon area they are changed around 20 m depth. To compared the results from Honanam coalfield and Suwon area, there are different rock type and geologic structure. However, the attitude of the discontinuities are changing at 20-30 m depth of underground.

• Economic and Environmental Geology
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• v.49 no.3
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• pp.193-199
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• 2016

Constancia mine is a deposit developed within Andahuaylas-Yauri Cu-Mo-Au metallogenic belt, southeastern Peru and is located in the southwestern part of Abancay deformation zone structurally as the porphyry copper deposit type. Mineralized zone in Constancia mine are composed of leached zone, secondary enrichment zone(ca. 1% Cu), mixed zone, primary mineralized zone(ca. 0.5%), skarn zone(ca. 1.5% Cu) from the upper part. Main country rock is monzonitic porphyry. Leached zone are characterized by the precipitation of limonite and looks brown in the outcrop. Oxidized zone have green due to the occurrence of copper oxide and secondary enrichment zone are characterized by the occurrence of chalcocite. Skarn zone are characterized by the occurrence of magnetite and garnet. Now, Hudbay, Canadian mining company, have 100% share about Constancia mine and started to produce commercially from January, 2015.

• Journal of the Korean Geotechnical Society
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• v.26 no.11
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• pp.111-123
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• 2010

The steel pipe of steel-concrete composite drilled shafts increases the pile strength and induces the ductile failure by constraining the deformation of the inner concrete. In this research, pile loading tests were performed to analyze the field applicability of a steel-concrete composite drilled shafts. The test ground consisted of 5~7 m thick soil underlying rock mass. The test piles consisted of two steel-concrete composite drilled shafts, which were the concrete filled steel pipe piles with the diameter of 0.508 m, and a concrete pile with the same diameter. The test results showed that the boundary between the upper steel composite section and the lower concrete section was structurally weak and needs to be reinforced by using a inner steel cage. If the boundary is located in deep depth, which is not influenced by lateral load, the allowable strength of the lower concrete section increases, so an economical design can be performed by increasing the design load of steel-concrete composite drilled shafts.

• Geomechanics and Engineering
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• v.36 no.1
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• pp.27-37
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• 2024

The roof-filling body system stability plays a key role in gob-side entry retained (GER). Taking the GER of the 1103 belt transportation roadway in Heilong Coal Mine as engineering background, stability analysis of roof-filling body system was conducted based on the cusp catastrophe theory. Theoretical results showed that the current design parameters of 1103 belt transportation roadway could ensure the roof-filling body system stable during the resistance-increasing support stage of the filling body and the stable support stage of the filling body. Moreover, a verified global numerical model in FLAC3D was established to analyze the failure characteristics including surrounding rock deformation, stress distribution, and plastic zone. Numerical simulation indicated that the width-height ratio of the filling body had a great influence on the stability of the roof-filling body system. When the width-height ratio was greater than 0.62, with the decrease of the width-height ratio, the peak stress of the filling body gradually decreased; when the width-height ratio was greater than 0.92, as the distance to the roadway increased, the roof stress increased and then decreased. The theoretical analysis and numerical simulation findings in this study provide a new research method to analyze the stability of the roof-filling body system in GER.

• Tunnel and Underground Space
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• v.30 no.4
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• pp.320-334
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• 2020

This study presents an application of hydro-mechanical coupled Particle Flow Code 3D (PFC3D) to simulation of fluid injection induced fault slip experiment conducted in Mont Terri Switzerland as a part of a task in an international research project DECOVALEX-2019. We also aimed as identifying the current limitations of the modelling method and issues for further development. A fluid flow algorithm was developed and implemented in a 3D pore-pipe network model in a 3D bonded particle assembly using PFC3D v5, and was applied to Mont Terri Step 2 minor fault activation experiment. The simulated results showed that the injected fluid migrates through the permeable fault zone and induces fault deformation, demonstrating a full hydro-mechanical coupled behavior. The simulated results were, however, partially matching with the field measurement. The simulated pressure build-up at the monitoring location showed linear and progressive increase, whereas the field measurement showed an abrupt increase associated with the fault slip We conclude that such difference between the modelling and the field test is due to the structure of the fault in the model which was represented as a combination of damage zone and core fractures. The modelled fault is likely larger in size than the real fault in Mont Terri site. Therefore, the modelled fault allows several path ways of fluid flow from the injection location to the pressure monitoring location, leading to smooth pressure build-up at the monitoring location while the injection pressure increases, and an early start of pressure decay even before the injection pressure reaches the maximum. We also conclude that the clay filling in the real fault could have acted as a fluid barrier which may have resulted in formation of fluid over-pressurization locally in the fault. Unlike the pressure result, the simulated fault deformations were matching with the field measurements. A better way of modelling a heterogeneous clay-filled fault structure with a narrow zone should be studied further to improve the applicability of the modelling method to fluid injection induced fault activation.