• Geomechanics and Engineering
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• 제16권5호
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• pp.539-545
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• 2018

Longitudinal Displacement Profile (LDP) is an appropriate tool for determination of the displacement magnitude of the tunnel walls as a function of the distance to the tunnel face. Some useful formulations for calculation of LDP have been developed based on the monitoring data on site or by 3D numerical simulations. However, the presented equations are only based on the tunnel dimensions and for different quality of rock masses proposed a unique LDP. In the present study, it is tried to present a new formulation, for calculation of LDP, on the basis of Rock mass quality. For this purpose, a comprehensive numerical simulation program was developed to investigate the effect of rock mass quality on the LDP. Results of the numerical modelling were analyzed and the least square technique was used for fitting an appropriate curve on the derived data from the numerical simulations. The proposed formulation in the present study, is a logistic function and the constants of the logistic function were predicted by rock mass quality index (GSI). Results of this study revealed that, the LDP curves of the tunnel surrounded by rock masses with high quality (GSI>60) match together; because the rock mass deformation varies over an elastic range.

• Structural Engineering and Mechanics
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• 제72권4호
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• pp.469-477
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• 2019

The understanding of tool-rock interaction mechanism is of high essence for improving the rock breaking efficiency and optimizing the drilling parameters in mechanical rock breaking. In this study, the tool-rock interaction models of indentation and cutting are carried out by employing the discrete element method (DEM) to examine the rock failure modes of various brittleness rocks and critical indentation and cutting depths of the ductile to brittle failure mode transition. The results show that the cluster size and inter-cluster to intra-cluster bond strength ratio are the key factors which influence the UCS magnitude and the UCS to BTS ratio. The UCS to BTS strength ratio can be increased to a more realistic value using clustered rock model so that the characteristics of real rocks can be better represented. The critical indentation and cutting depth decrease with the brittleness of rock increases and the decreasing rate reduces dramatically against the brittleness value. This effort may lead to a better understanding of rock breaking mechanisms in mechanical excavation, and may contribute to the improvement in the design of rock excavation machines and the related parameters determination.

• Geomechanics and Engineering
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• 제12권1호
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• pp.53-69
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• 2017

Rock burst may cause serious casualties and property losses, and how to conduct effective monitoring and warning is the key to avoid this disaster. In this paper, we reviewed both the rock burst mechanism and the principle of using electromagnetic radiation (EMR) from coal rock to monitor and forewarn rock burst, and systematically studied EMR monitored data of 4 rock bursts of Qianqiu Coal Mine, Yima Coal Group, Co. Ltd. Results show that (1) Before rock burst occurrence, there is a breeding process for stress accumulation and energy concentration inside the coal rock mass subject to external stresses, which causes it to crack, emitting a large amount of EMR; when the EMR level reaches a certain intensity, which reveals that deformation and fracture inside the coal rock mass have become serious, rock burst may occur anytime and it's necessary to implement an early warning. (2) Monitored EMR indicators such as its intensity and pulses amount are well and positively correlated before rock bursts occurs, generally showing a rising trend for more than 5 continuous days either slowly or dramatically, and the disaster bursts generally occurs at the lower level within 48 h after reaching its peak intensity. (3) The rank of EMR signals sensitive to rock burst in a descending order is maximum EMR intensity > rate of change in EMR intensity > maximum amount of EMR pulses > rate of change in the amount of EMR pulses.

• 수산해양교육연구
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• 제27권4호
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• pp.1184-1193
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• 2015

Monitoring for megalocytivirus infection was conducted for ten months from March to December in 2013 in 15 aquatic farms culturing, red sea bream, rock bream, rock fish and black sea bream around Tongyoung coastal area in Korea, to assess spatial and temporal variability of detection prevalence, and to explore possible links with seawater temperature. In nested-PCR targeted major capsid protein (MCP) gene, asymptomatic megalocytivirus infection was detected in the externally healthy farmed fish with a significant prevalence in range from 0 to 58.3% for ten months. Higher prevalence of megalocytivirus (46.7% - 57.1%) was observed in high water temperature season from September to November than that in other months with lower prevalence of 0.0% to 20.0%. Even though an acute infection of megalocytivirus was occurred in rock bream (positive in the first PCR) with high mortality in one of fifteen farms, there was no expansion or transmission of the disease to the rock fish and red sea bream culturing in net cage just proximal to the rock bream cage in which disease outbreaked. Nucleotide sequence analysis of the cloned MCP gene isolated asymptomatically infected rock fish revealed that the megalocytivirus in this study was clustered together with the rock bream iridovirus (RBIV) under the subgroup II of the genus megalocytivirus (Iridoviridae), which is known to be the major megalocytivirus strain in Korea. The typical histopathological signs were not found in the spleen of rock fish asymptomatically infected by megalocytivirus. Experimental infection of rock bream with the spleen homogenate of the rock fish infected asymptomatically did not induce any mortality unlike the homogenate of infected rock bream with hih mortlity. However, these results may suggest that the asymptomatic infection of megalocytivirus in other fish species can be a potential risk threatening aquaculture industries as a transmission factor of megalocytivirus to susceptible fish species, especially rock bream.

• Geomechanics and Engineering
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• 제36권6호
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• pp.575-587
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• 2024

The contact pressure between the surrounding rock and the support is an important indicator of the surrounding rock pressure. There has been a bottleneck in the prediction of contact loads between surrounding rock and primary support in deep-buried mountain tunnels. The main reason is that a reliable method wasn't existed to quantify the contact loads. This study had been taken into account the flexible support role of the primary support, and the fitting curve of surrounding rock deformation for dynamic tunnel construction was proposed. New formulas for the calculation of contact loads between surrounding rock and primary support were obtained by inversion. Comparative analysis of the calculation results with numerical simulation verified the reliability of the calculation method in this study. It can be seen from the analyses that the contact load between surrounding rock and primary support increases, remains unchanged and decreases during acceleration, uniform velocity and deceleration, respectively, and the deformation of the surrounding rock in the acceleration and deceleration stages cannot completely converted into contact loads. The contact loads between surrounding rock and primary support of medium-strength and weak surrounding rock tunnels are generally within 150 kPa and 1 MPa, respectively. For tunnels with weak surrounding rock, advanced support can be installed to reduce the unique release coefficient λ₀ and the value of the constant D, with the purpose of reducing the contact loads between surrounding rock and primary support. Changes in support parameters have a small effect on the contact loads between surrounding rock and primary support, but increase or decrease the safety factor, resulting in a waste of resources or a situation that threatens the safety of the support. The results of this research provide guidance for the prediction of contact loads between surrounding rock and primary support for dynamic tunnel construction.

• 터널과지하공간
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• 제34권1호
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• pp.28-53
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• 2024

원자력발전에 따라 필수적으로 발생하는 고준위방사성폐기물은 원자력발전이 시행된 나라 내 처분이 원칙이다. 고준위방사성폐기물의 심층처분을 위한 처분 지역과 모암의 결정은 과학적 방법뿐만 아니라 정치, 경제, 사회적으로 중요한 이슈이다. 현재까지 전 세계적으로 처분 모암으로 고려되는 암종은 결정질암, 퇴적암인 이암, 화산암인 응회암, 암염 등이 있다. 그러나 국내의 경우 지질학적으로 암염을 제외한 다양한 암종이 복잡하게 분포하고 있다. 본 논문에서는 고준위방사성페기물처분장의 처분 모암에 대한 다양한 암종 연구의 예비결과와 함께 전국규모의 지질학적, 암석역학적 특성을 분석하였을 뿐만 아니라, 후보 암종에 대한 심부 시추조사 사례들을 통하여 특성을 검토하고 처분 모암으로서 다양한 암종들의 가능성을 제시하고자 하였다. 또한 전국규모의 광역적 특성 분석, 문헌 조사, 상세 사례분석 등을 통하여 고준위방사성폐기물 심층처분을 위한 후보 암종으로 결정질암인 쥐라기 화강암과 백악기 퇴적암 중진주층과 진동층을 도출하였다. 그러나 본 논문에서 도출된 후보 암종들에 대해 연구된 자료의 양이 적기 때문에 처분심도, 지역적 특성, 다학제적인 검토 등에 대한 추가적이고 상세한 분석이 수행된 후 신중히 처분 암종이 결정되어야 할 것으로 사료된다.

• 한국암반공학회:학술대회논문집
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• 한국암반공학회 2011년도 추계 총회 및 창립 30주년 기념 심포지엄
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• pp.69-87
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• 2011

• 한국암반공학회:학술대회논문집
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• 한국암반공학회 2008년도 국제학술회의
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• pp.115-121
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• 2008

• 터널과지하공간
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• 제13권4호
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• pp.279-286
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• 2003

최근의 터널설계에 있어서 지보패턴 선정시 전기비저항탐사 결과를 효과적으로 황용하기 위하여 전기비 저항 역산결과와 암반분류와의 상관관계를 도출해 내고자 하는 시도가 이루어지고 있다. 그러나 전기비저항탐사결과를 고려한 예상지보패턴과 실제로 시공된 지보패턴 결과를 비교한 연구는 찾아보기 힘들다. 본 연구에서는 실제 터널굴진 상태에서 막장관찰에 기초한 암반분류 및 지보패턴 선정과 시공 전 수행한 전기비저항 탐사자료를 비교함으로씨 전기비저항 탐사 결과가 어느 정도의 신뢰도로 이용될 수 있는가를 살펴보고자 한다. 전기비저항 자료와 암반분류의 정량적인 상관성을 얻기 위하여 암반분류값으로 RMR(Rock mass rating)을 기본으로, RCR(rock condition rating), N(Rock mass number), Q-system 등을 이용하였다. 전기비저항탐사는 공간적 해상도가 낮기 때문에 후처리 과정으로 크리깅 기법을 사용하여 해상도를 향상시키고자 하였다. 상관도 분석 결과, 2차원 전기비저항탐사결과는 정성적인 경향을 살펴보는데 적합한 것으로 나타났다 3차원 전기비저항탐사 결과와의 상관관계는 매우 높은 것으로 나타나 신뢰도 높은 암반분류에 적용 가능하리라 예상된다.

• 한국암반공학회:학술대회논문집
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• 한국암반공학회 2008년도 국제학술회의
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• pp.173-181
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• 2008