• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.1330-1333
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• 2009

The soil nailing method had used in variable construction field because of construction convenience and reinforcement effect. Especially, the removal soil nailing method is useful support system in vertical excavation. In this study, to develop the wedge type removable soil nailing method for improvement of the removal soil nailing method. Because of the reinforcement materials is most important in soil nailing method, to evaluate the mechanical characteristics during laboratory strength test in this study. To conduct bond strength test of deformed bar combined with a wedged screw inside plastic fixed socket for evaluate the strength characteristics of wedge type removable soil nailing method and evaluate the strength characteristics of fixed socket based on laboratory tests.

• Tunnel and Underground Space
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• v.14 no.6 s.53
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• pp.440-449
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• 2004

Rock mass includes natural discontinuities such as joints and faults during its formation. Discontinuities are also referred as planes of weakness because of their weak mechanical characteristics. In the design of underground structures, it is necessary to consider the properties of discontinuities to insure the stability. During the excavation of a tunnel, these discontinuities have to be identified as early as possible so that proper change in excavation method or support design can be made accordingly. The excavation of the tunnel in a stable rock mass causes a 3-dimensional arching effect around the excavation face. It was revealed by previous studies that the existence of a weak zone or a fault zone ahead of tunnel foe induces a typical displacement tendency of convergence. For better understanding of the meaning of influence/trend lines of various displacement components, three-dimensional numerical analyses were conducted while varying deformation moduli, thicknesses and orientations of discontinuities. Numerical results showed that the changes in influence/trend lines of various displacement components were very similar to those by measurements. The discrepancies from the expected values were dependent on the physical properties, thicknesses and orientations of discontinuities.

• Journal of Dental Anesthesia and Pain Medicine
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• v.18 no.5
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• pp.277-285
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• 2018

Chemo-mechanical caries removal methods are known to be more effective compared with conventional methods in pain reduction. $Carie-care^{TM}$, a chemo-mechanical caries removal agent, was introduced in 2010 but a systematic review of its efficacy has not yet been performed. The purpose of this study was to investigate the effectiveness of $Carie-care^{TM}$ on the outcomes of treatment of caries in children and adolescents. The primary outcome was pain while the secondary outcomes included complete caries removal (CCR), time, need for local anesthesia and behavioral response changes. A Comprehensive literature search was performed in PubMed, EMBASE, and the Cochrane Library up to 30 September 2018. The following keywords were used in the search: 'chemo-mechanical caries removal agent', 'dental caries', 'Carie-care', 'chemo-mechanical caries removal', 'chemo-mechanical caries excavation', other related keywords, and their combinations. From 942 studies identified, 16 were analyzed. Finally, 4 studies met the eligibility criteria and 260 teeth in 120 children and adolescents were included in this review. This review showed that $Carie-care^{TM}$ reduces pain during caries treatment but requires a longer time for effective treatment than conventional methods. Local anesthesia was not required in the Chemo-mechanical caries removal (CMCR) group. In addition, dental anxiety decreased compared to the control group, and co-operation was more positive. Therefore, it may be a useful alternative to conventional methods in children and adolescents, but further verification through additional studies is needed.

• Geomechanics and Engineering
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• v.15 no.3
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• pp.899-910
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• 2018

Terrace deposits are often encountered in portal areas and tunnels with low overburden. They are challenging to excavate considering their great mechanical and spatial heterogeneity and a very high stiffness contrast within the ground. Terrace deposits are difficult to characterize, considering that samples for laboratory testing are almost unfeasible to obtain, and laboratory tests may not be representative due to scale effects. This paper presents the approach taken for their characterization during the design stage and their posterior validation performed during construction. Lessons learned from several tunnels excavated on terrace deposits on the Bogota-Villavicencio road (central-east Colombia), suggest that based on numerical simulations, laboratory testing and tunnel system behaviour monitoring, an observational approach allows engineers to optimize the excavation and support methods for the encountered ground conditions, resulting in a more economic and safe construction.

• Plant Journal
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• v.8 no.2
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• pp.70-81
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• 2012

The study aims to supplement facility management plan and safety regulations & standard of oil pipeline by searching and reviewing related regulation & standard inside and outside of the country. Korean regulation & standard is reviewed based on harbor and fishery design standard of the ministry of maritime affairs and fisheries, general technology standard of oil pipeline safety regulation, gas excavation construction and safety maintenance indicator of Korea gas corporation. Global regulation & standard is reviewed based on U.S standard inspection for offshore pipeline and Europe/Mexico standard inspection for offshore pipeline. The contents of offshore pipeline installation is inserted into pipeline sector for objected facilities of safety inspection regulation & standard and, the standard of safety inspection for offshore pipeline is newly presented into pipeline maintenance part of the planning facilities management with its inspection period and method.

• Explosives and Blasting
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• v.15 no.1
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• pp.44-60
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• 1997

The design of underground cavern is basically governed by the mechanical properties of ground mass distributed around excavation. It is seldom possible to consider all the factors of ground mass properties in the evaluation of ground mass behavior as well as to classify those factors to a simple category. Until computer sciences have developed to calculate complex and laborious mechanical simulation of underground openings, ground behavior was quantitatively and qualitatively evaluated using empirical classification system. In this paper, analysis methods of ground behavior for underground cavern using the prediction of loosening zone, empirical method derived from rock mass classification and element stress analysis are described with chronological sequence.

• The Journal of Engineering Geology
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• v.1 no.1
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• pp.38-53
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• 1991

The design of underground cavern is basically governed by the mechanical properties of ground mass distributed around excavation. It is seldom possible to consider all the factors of ground mass properties in the evaluation of ground mass behavior as well as to classify those factors to a simple category. Until computer sciences have developed to calculate complex and laborious mechanical simulation of underground openings, ground behavior was quantitatively and qualitatively evaluated using empirical classification system. In this paper, analysis methods of ground behavior for underground cavern using the prediction of loosening zone, empirical method derived from rock mass classification and element stress analysis are described with chronological sequence.

• Magazine of the Korean Society of Agricultural Engineers
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• v.42 no.6
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• pp.98-105
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• 2000

Recently, the construction method of high pressure jet-grouting is in wide-use, for the purpose of structure foundation ground, reinforcing of ground behind propped retaining walls and cut-off in order to perform safe construction of underground excavation work. This study was performed a serious of tests of field permeability and unconfined compressive strength upon ground improved established on the ground behind propped retaining walls and examined proper jet mechanism by changing the construction parameter value of high pressure jet-grouting. In addition, we got the conclusion like the followings as a result of inspecting the condition of earth pressure distribution and deformation, using elasto-plastic method and FEM. 1. In that characteristics of strength of ground improved, with the same condition of construction parameter, unconfined compressive strength of sand gravel is shown bigger than that of silty sand by about 1.6 times and cut-off effect is shown to have effect of reducing the permeability of original ground by about 10$^{-2}$ ~10$^{-3}$ cm/s. 2. As a result of analysis of figures of horizontal displacing quantity of propped retaining walls materials regarding before and after High pressure jet- grouting through FEM, the reducing quantity of 0.1~0.3mm in maximum horizontal displacement is shown.

• Journal of Industrial Technology
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• v.23 no.A
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• pp.69-81
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• 2003

Numerical analysis is important for the design, construction and maintenance of large caverns. The rock mass contains generally discontinuities such as faults, joints and fissures. The mechanical behavior and geometric characteristics of these discontinuities would have a significant impact on the stability of the caverns. In this research the Distinct Element Method(DEM) was used to analyze the structural stability of the large cavern. The Barton-Bandis Joint Model (B-B J.M) was used as a constitutive model for the joint. In addition, two different cases 1) analysis with a support system and 2) analysis with no support system, were analyzed to optimize a support system and to investigate reinforcing effects of a support system. The most significant parameters of in-situ stress, JRC of in-situ natural joints, and spatial distribution characteristics of discontinuities were acquired through field investigation. Displacement (horizontal, joint shear), maximum joint opening, maximum and minimum principal stresses, range of relaxed zone, rockbolt axial forces and shotcrete stresses were calculated at each excavation stage. As a result of analysis the calculated values proved to be under the allowable value Rockbolts also proved to be an efficient support measure to control joint shear displacement which had significant effects on extending the relaxed zone. As a consequence, the structural stability of the cavern was assured with an appropriate support system.

• Explosives and Blasting
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• v.35 no.1
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• pp.43-52
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• 2017

Mountain and hill areas occupy by more than 70% in South Korea and Rock drilling should be applied in order to reduce noisy & vibration from massive civil engineering business such as road expansion, high-way construction, subway construction and construction of site renovation such as a newly-built & re-development of apartment, newly-built of high-rising building in downtown area. As Blasting noise & vibration such as vibration, noise, fly rock etc caused by blasting operation from large small scale construction occurs, neighboring residents who demand the compensation file a civil complaint so that the business reach a deadlock. As the excavation method for these areas, There are blasting of micro-vibration, mechanical excavation method(Rock splitter, Breaker etc), similar blasting method(plasma, gel fragmentation etc) to date. In this study, we are trying to find the feature & performance which get improved economic feasibility & construct ability through improving sympathetic detonation of New KINECKER-I used in blasting of micro-vibration & formulation and would provide convenience for use by introducing standard blasting pattern & construction method. Also, checked and confirmed all the blasting with connecting cap has been cleary detonated.