• Tunnel and Underground Space
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• v.29 no.3
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• pp.197-213
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• 2019

We simulated the fault reactivation experiment conducted at 'Main Fault' intersecting the low permeability clay formations of Mont Terri Underground Research Laboratory in Switzerland using TOUGH-FLAC simulator. The fluid flow along a fault was modelled with solid elements and governed by Darcy's law with the cubic law in TOUGH2, whereas the mechanical behavior of a single fault was represented by creating interface elements between two separating rock blocks in FLAC3D. We formulate the hydro-mechanical coupling relation of hydraulic aperture to consider the elastic fracture opening and failure-induced dilation for reproducing the abrupt changes in injection flow rate and monitoring pressure at fracture opening pressure. A parametric study was conducted to examine the effects of in-situ stress condition and fault deformation and strength parameters and to find the optimal parameter set to reproduce the field observations. In the best matching simulation, the fracture opening pressure and variations of injection flow rate and monitoring pressure showed good agreement with field experiment results, which suggests the capability of the numerical model to reasonably capture the fracture opening and propagation process. The model overestimated the fault displacement in shear direction and the range of reactivated zone, which was attributed to the progressive shear failures along the fault at high injection pressure. In the field experiment results, however, fracture tensile opening seems the dominant mechanism affecting the hydraulic aperture increase.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.20 no.6
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• pp.101-107
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• 2020

Road surface measurement is an essential process for quantifying the degree and displacement of roughness in road surface management. For safer road surface management and quick maintenance, it is important to accurately measure the road surface while mounted on a vehicle. In this paper, we propose a sophisticated road surface measurement system that can be measured on a moving vehicle. The proposed road surface measurement system supports more accurate measurement of the road surface by using a high-performance line laser sensor. It is also possible to measure the transverse and longitudinal profile by matching the position information acquired from the RTK, and the velocity adaptive update algorithm allows a manager to monitor in a real-time manner. In order to evaluate the proposed system, the Gocator laser sensor, MRP module, and NVIDIA Xavier processor were mounted on a test mobile and tested on the road surface. Our evaluation results demonstrate that our system measures accurate profile base on the MSE. Our proposed system can be used not only for evaluating the condition of roads but also for evaluating the impact of adjacent excavation.

• Journal of Korean Tunnelling and Underground Space Association
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• v.25 no.2
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• pp.141-155
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• 2023

Monitoring technology based on electrical resistivity is widely used for non-destructive data collection and health analysis of underground structures and tunnels. Vulnerable sections such as fault zone generates many problems during construction of the tunnel. These problems cause displacement and stress changes of the ground. Therefore, it is necessary to predict the state of the fault zone section to ensure the mechanical stability of the underground structure. Monitoring the size of joints and the porosity of the fillings is essential for rocks. Previous studies have not considered the variety of fillings in rock joints. In this study, electrical resistivity tests were conducted according to the particle mixing state of the sandy fillings. When the size of fillings is decreased at the constant porosity, the electrical resistivity tends to increase. The results of this study are expected to be useful as basic electrical resistivity data for predicting the ground conditions and evaluation of the ground behavior that is containing sandy fillings in the rock joint for tunnels.

• Journal of the Korean GEO-environmental Society
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• v.17 no.4
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• pp.39-46
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• 2016

The final stability analysis of the tunnel structure is generally evaluated by performing site monitoring to determine whether or not the measured value through the convergence after the completion of excavation in the face. When the ground conditions are so poor, the reinforcement around the tunnel was applied for enhancing the stability of tunnels. For the additional tunnel crown collapse or excessive displacement have occurred under construction, correlation analysis were performed for the comparison construction and numeric analyses. In this paper, we investigated the collapse types, tunnel collapse were mostly occurs at the crown and they were analyzed because of the geological conditions in the collapse zone. And also, it was analyzed as being correlated in the crown of tunnel exists a fault fracture zone which extends to the surface part. Thus, in case of ground conditions such as fault fracture zone with a tunnel extending from the crown to the surface, the behavior is larger than the behavior predicted by numerical method.

• International Journal of Naval Architecture and Ocean Engineering
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• v.6 no.2
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• pp.442-458
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• 2014

Wave induced vibrations increase the fatigue and extreme loading, but this is normally neglected in design. The industry view on this is changing. Wave induced vibrations are often divided into springing and whipping, and their relative contribution to fatigue and extreme loading varies depending on ship design. When it comes to displacement vessels, the contribution from whipping on fatigue and extreme loading is particularly high for certain container vessels. A large modern design container vessel with high bow flare angle and high service speed has been considered. The container vessel was equipped with a hull monitoring system from a recognized supplier of HMON systems. The vessel has been operating between Asia and Europe for a few years and valuable data has been collected. Also model tests have been carried out of this vessel to investigate fatigue and extreme loading, but model tests are often limited to head seas. For the full scale measurements, the correlation between stress data and wind data has been investigated. The wave and vibration damage are shown versus heading and Beaufort strength to indicate general trends. The wind data has also been compared to North Atlantic design environment. Even though it has been shown that the encountered wind data has been much less severe than in North Atlantic, the extreme loading defined by IACS URS11 is significantly exceeded when whipping is included. If whipping may contribute to collapse, then proper seamanship may be useful in order to limit the extreme loading. The vibration damage is also observed to be high from head to beam seas, and even present in stern seas, but fatigue damage in general is low on this East Asia to Europe trade.

• Journal of Soil and Groundwater Environment
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• v.17 no.6
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• pp.9-22
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• 2012

Though geologic storage of $CO_2$ (GS) is considered as an attractive technological option to enormously reduce greenhouse gases emission into the atmosphere, many concerns on potential environmental and health risks associated with $CO_2$ leakage have been raised. In particular, groundwater contamination due to the brine displacement by a pressure build-up and the acidification by leaked $CO_2$ is paid a special attention. Therefore, integrated regulatory frameworks have been established by law in many countries to secure the permanent containment of injected $CO_2$. Regulatory frameworks deal with entire processes of GS, including site selection, monitoring and post-closure environmental management. This review paper provides a summary of regulatory frameworks in USA (U.S. EPA Geologic Sequestration Rule) and EU (Geologic $CO_2$ Sequestration Directive). The regulatory framework to properly address environmental issues should be established for the deployment of CCS projects in Korea.

• Geomechanics and Engineering
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• v.23 no.2
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• pp.127-137
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• 2020

To study the reverse fault formation process and the stress evolution feature, a simulation test system of reverse fault formation is developed based on the analysis of reverse fault formation mechanism. The system mainly consists of simulation laboratory module, operation console and horizontal loading control system, and data monitoring system. It can represent the fault formation process, induce fault crack initiation and simulate faults of different throws. Simulation tests on reverse fault formation process are conducted by using the simulation test system: horizontal loading is added to one side of the model. the bottom rock layer cracks under the effect of the induction device. The crack dip angle is about 29°. A reverse fault is formed with the expansion of the crack dip angle towards the upper right along the fracture surface and the slippage of the hanging wall over the foot wall. Its formation process unfolds five stages: compressive deformation of rock, local crack initiation, reverse fault penetration, slippage of the hanging wall over the foot wall and compaction of fault plane. There is residual structural stress inside rock after fault formation. The study methods and results have guiding and referential significance for further study on reverse fault formation mechanism and rock stress evolution.

• Journal of Korean Tunnelling and Underground Space Association
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• v.19 no.1
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• pp.1-9
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• 2017

In this study, a test-bed system simulated a tunnel and concrete track is tested on cite and invested an allowed limit of multi-layered sound absorbing panel for reducing noise reflected on the concrete track in train tunnel considering the criteria and limitation on the theoretical back ground. The studied results are an effective evaluating system of the sound absorbing coefficient influenced fluid effects depending on the vehicle speed in the urban train tunnel and measuring not only structural behaviors of maximum displacement and acceleration of the panel but also dynamic characteristics of damping ratio and natural frequency.

• Journal of Korean Society of societal Security
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• v.2 no.2
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• pp.85-90
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• 2009

In recent days, climatic change cause abnormal weather all over the world and we have a great loss of life and property every year. In Korea, we suffer from landslide problem because large regions of Korea Peninsula are composed of mountain. In order to detect rapidly and to take follow-up measures of disaster, the remote sensing is being used actively as conventional field survey has many restrictions in accessibility because of more time and man power requirement. In additions interferometric SAR is one of the techniques that have our attention because it can provide many kinds of accurate surface information without restriction of atmospheric and ground conditions by using L-band. In this study, we aimed to monitor the displacement of mountain area in Kangwondo and this results will be used for detecting landslide. Also we build the web system for detecting and analyzing the landslide.

• Structural Monitoring and Maintenance
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• v.7 no.3
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• pp.215-231
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• 2020

In a reinforced concrete building different shapes of column are adopted depending on the structural orientation and the architectural aspect. When there is an increase in loading due to changes in usage or revision in the design codes these columns need to be strengthened for enhanced performance during their service life. Strengthening materials such as carbon fiber and glass fiber polymer has been successfully used however, due to high cost application other alternative materials need to be explore. Galvanized steel wire mesh (GSWM) is one of the suitable materials locally available. High tensile strength, low weight, corrosion resistance, easy installation, minimum change in dimensions of the sections and cost effectives are the advantages of GSWM. Therefore, in this paper, four different shapes of column such as circular, square, rectangular and L were wrapped with different layers GSWM and jacketed with mortar. All the specimens were tested under axial compression. The objective of the study is to investigate the effectiveness of GSWM as a confining material for strengthening of column having varying shape. Test results shows that the axial strength enhanced with wrapping of GSWM jacket and a circular column presented the highest load carrying capacity and ductility as compared to the others. From the study of 22 column specimens, it is found that axial load is increased upto 20% and 19% when circular and square column are strengthened with one wrap of GSWM respectively, while a rectangular and L column required a wraps of two and three layers respectively in order to achieved the same load capacity as that of a circular column. Based on the present study, it is concluded that GSWM can be effectively used for strengthening of different shapes of concrete columns economically.