• Journal of the Korean Geotechnical Society
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• v.23 no.5
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• pp.77-88
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• 2007

Lateral earth pressure and horizontal displacement of the diaphragm walls constructed in multi-soil layers were analyzed by the field instrumentation from six building construction sites in urban area. The distribution of the developed earth pressure of the anchored diaphragm walls during excavation shows approximately a trapezoid diagram. The maximum earth pressure of anchored diaphragm walls corresponds to $0.45{\gamma}H$ and the earth pressure acts at the upper part of the walls. The maximum earth pressure is two times larger than the empirical earth pressure of flexible walls in sands suggested by Terzaghi and Peck(1967), Tschebotarioff(1973), and Hong and Yun(1995a). The horizontal displacement of diaphragm walls is closely related with supporting systems such as struts, anchors, and so on. The horizontal displacement of anchored walls shows less than 0.1 percent of the excavated depth, and the horizontal displacement of strutted walls shows less than 0.25 percent of the excavated depth. Therefore, the restraining effect of horizontal displacement to the anchored diaphragm walls is larger than the strutted diaphragm walls. In addition, since the horizontal displacement of the diaphragm walls is lower than the criterion, $\delta=0.25%H$, used for control the anchored retention wall using soilder piles, the safety of excavation sites applied with the diaphragm walls is pretty excellent.

• Explosives and Blasting
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• v.29 no.2
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• pp.59-66
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• 2011

A variety of risks caused by natural, technological and biological hazards threaten a business continuity of an organization. Business continuity is very important issue for all organizations and its proper management may control success and failure of an organization. Business continuity plan (BCP) may be defined as a management process which provides a business continuity. BCP includes risk management, operational continuity plan, response/ recovery, exercise/study and crisis communication, etc. Risk management is a systematic method to identify, analyze, evaluate and treat emergency risks and risk assessment is composed of identifying, analyzing and evaluating emergency risks. Risk assesment is the first step for making BCP. In this study, risk assessment has been conducted for sewer laying project. Through assessing risks, 18 risks that may threaten the construction operation are identified and it is founded to be that high levels of risks which require treatment are 'collapse of excavation surface', 'breakage of ground infra-facilities', 'noise & dust dispersion' and 'rise of material costs'.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.3
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• pp.23-28
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• 2019

A track type underwater construction robot(URI-R) which can trench on seabed is being developed by Korea Institute of Ocean Science & Technology. During the underwater trenching work, the robot is exposed high intensive noise and vibration so the underwater localization signal may not be obtained properly by the acoustic tracking system. Therefore it is necessary to research about continuous localization even though the measured position signal comes in intermittently. In this paper, the experiments were carried out on land to simulated the underwater operating environment characteristics. To estimate its position, inertial navigation system and global navigation satellite system are used. The effects of the period variation while localizing is investigated by the experiments, and the application for URI-R is proposed.

• Computational Structural Engineering
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• v.9 no.4
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• pp.199-207
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• 1996

In the past decade soft clay shield tunneling technology have been improved to permit continuous support to the face of a tunnel. These advanced shield can be operated such that an initial heaving is created, this helps to decrease the inward soil movement into the tail void. In this paper, the measurement of slurry shield and EPB shield were used and two dimensional elasto-plastic programs EPSHILD developed for shield tunnel analysis were approved. The excavation steps corresponding with construction stages were settled and heaving load, load factors were considered. This study is based on the instantaneous settlement which is occured in the process of shield construction but not the secondary settlement by consolidation.

• Journal of the Korean Geotechnical Society
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• v.19 no.2
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• pp.39-48
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• 2003

Previous analytical models for key blocks have been based on the assumption of infinite persistent discontinuities. In this paper, a key block analysis method considering the finite persistence of discontinuities is proposed as a stability evaluation method in tunnel constructions, and then applied to an actual example site. Three-dimensional rock block identification with consideration of the persistence of discontinuities is performed by using discontinuity disk model. The removability and stability analyses of rock blocks formed by the identification method are performed. The identification method can handle convex and concave shape blocks. In order to demonstrate the applicability of this developed numerical method to the stability evaluation in tunnel constructions, the analytical results are examined and compared one another.

• Journal of the Korean GEO-environmental Society
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• v.18 no.9
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• pp.5-9
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• 2017

On the flow of groundwater, the effect of consecutive column-wall in underground as a hydraulic barrier could be identified by conventional geotechnical methods ((1)visualiy identification of wall mass after underground excavating, (2)uniaxial compressive strength test for core of wall mass in underground, (3)in-situ permeability test in the hole after coring wall mass). However, for the cut off the leakage or infiltration of very high concentrated leachate from the waste landfill or the contaminated groundwater, the waterproof effect of consecutive column-wall in underground should be verified more objectively, by in-situ measuring of pH, temperature and salinity. and by evaluating of their consistency and similarity throughout analyzing the characteristics of basic components and their profiles through the series of chemical experiments. Furthermore, its waterproof effect could be verified additionally throughout deciding the similarity more simply by comparing the general distribution patterns including the difference of high and low peaks from the chromatograms using GC-MS for surrounding groundwater.

• Journal of the Korean Geotechnical Society
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• v.20 no.3
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• pp.151-159
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• 2004

This paper describes a systematic way of identifying the horizontal coefficient of consolidation of clayey soil by applying an optimization technique to the early part of dissipation data measured from the self-boring pressuremeter strain holding test. An analytical solution developed by Randolph ＆ Wroth (1979) was implemented in normalized form to express the build-up of excess pore pressures as a function of the rigidity index and subsequent dissipation of excess pore pressures around a pressuremeter Horizontal coefficient of consolidation was determined by minimizing the differences between theoretical and measured excess pore pressure curves over 50% degree of dissipation range using optimization technique. The effectiveness of the proposed back-analysis method was examined against the real fled performances obtained from pressuremeter strain holding tests at Gimje and Yangsan site. It is shown that the proposed back-analysis method can evaluates the rational horizontal coefficient of consolidation, which is similar to those obtained from the piezocone dissipation test. Furthermore, proposed method can evaluate appropriate coefficient of consolidation for soil under partially drained condition.

• Journal of Korean Tunnelling and Underground Space Association
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• v.24 no.5
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• pp.395-409
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• 2022

To overcome the limitation of conventional rock excavation methods, the excavation with abrasive waterjet has been actively developed. The abrasive waterjet excavation method has the effect of reducing blasting vibration and enhancing the excavation efficiency by forming a continuous free surface on the rock. However, the waterjet cutting performance varies with rock fracturing characteristics. Thus, it is necessary to analyze the cutting performance for various rocks in order to effectively utilize the waterjet excavation. In this study, cutting experiments with the high pressure waterjet system were performed for basalt and granite specimens. Water pressure, standoff distance, and traverse speed were determined as effective parameters for the abrasive waterjet cutting. The cutting depth and width of basalt specimens were analyzed to compare with granite results. The averaged cutting depth of basalt was shown in 41% deeper than granite; in addition, the averaged cutting width of basalt was formed by 18.5% narrower than granite. The results of this study are expected to be useful basic data for applying rock excavation site with low strength and high porosity such as basalt.

• The Journal of Engineering Geology
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• v.3 no.3
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• pp.215-230
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• 1993

In-situ rock mass demonstrates the variety of structural features, and especially the mechanical and spatial characteristics of joint (or joint system) greatly affect the deformation and fallure strength of the rock mass. In this study finite element model capable of analyzing the viscoplastic behavior of reinforced jointed rock mass has been developed based on equivalent material approach. Accuracy and reliability of the numerical model have verified by simuiating the behavior of simplified block model and comparing the results with analytic solutions. Practical applicability was also demonstrated by analyzing the time-dependent behavior of underground oil storage tunnel and assessing the reinforcement effect of rockbolt.

• Journal of Korean Tunnelling and Underground Space Association
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• v.12 no.3
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• pp.275-283
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• 2010

Recently, the observational design and construction method in tunnels has been becoming important. Rock masses include various discontinuities such as joints, faults, fractures, bedding planes, and, cracks. The behavior of tunnels in hard rocks, therefore, is generally controlled by various discontinuities. In this study, a new key block analysis method for observational design and construction method in tunnels is proposed, and then applied to the actual tunnel with a super-large cross-section. The proposed analysis method considers finite persistence of discontinuities. The new analysis method can handle concave and convex shaped blocks. To demonstrate the applicability of this key block analysis method for observational design and construction method in tunnels, the analysis results are examined and compared with those of the conventional method.