• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.10
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• pp.1069-1077
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• 2015

In tunnel excavation using blast, the wire saw rock cutting method generates a discontinuity perimeter around the center cut, and thus prevents blast vibration propagation to reduce vibration and noise. Therefore, the method is expected to be easy to use and economical compared with other methods. In this paper, the cutting mechanism of wire saw in tunnel excavation is investigated. A model describing the changes in cutting depth and wire saw shape inside a rock during cutting is established and validated for this purpose. Through a simulation using the model, the important characteristics of wire saw cut are investigated, and the influences of cutting conditions, such as wire saw tension, wire saw speed, feed speed, depth, and diameter of boring, on cutting performance are also examined. A method to improve the cutting performance is proposed based on the results.

• Tunnel and Underground Space
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• v.21 no.3
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• pp.192-204
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• 2011

In this study, 3-D analyses were conducted while taking every construction stage into account. Then 2-D analyses were conducted which yield the same results with the 3-D results. The crown settlement normalized by the ultimate value was compared during the process to overcome the discrepancy caused by different dimensions. When a bench or a core is left uncut to give extra support to the face and eventually the whole excavation boundary, this extra supporting effect also has to be included in the analysis. In this study, this effect is also implemented in terms of the load distribution factor. When the length of the bench is very short compared to the diameter of the tunnel in such cases as in short bench cut or in mini-bench cut, the supporting effect of the face does not disappear even after the bench is completely excavated and supported since the face is still too close to the point of interest. The 4th load distribution factor was defined to stand for the advance of the face after the completion of the excavation cycle. The 4th load distribution factor turned out to be very useful in determining the load distribution factors when a tunnel is excavated by bench cut with various bench lengths under different initial conditions.

• Explosives and Blasting
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• v.21 no.2
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• pp.1-13
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• 2003

Overbreak or underbreak is one of the most important factors in evaluating the results of a tunnel blasting. Overbreak, which depends on the quality of rock, the type and quantity of explosives, and drilling conditions, has been a target of challenge to many blasting engineers because it directly affects construction cost. Drilling is generally known as one of the primary factors to generate overbreak. This study presents a real working model to reduce overbreak based on the analysis of drilling accuracy and overbreak generated from various working methods related to drilling. As the first step of the study, 45 experiments have been performed. The factors investigated are: marking contour line, the position of perimeter holes, the change of look-out with drilling rig position, and the proper space between perimeter holes. It is concluded that workers and engineers＇ will and efforts are the most important factors to reduce overbreak and that improving drilling method and pattern could reduce overbreak to a considerable amount.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.9 no.1
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• pp.17-25
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• 1991

A foundation excavation is necessarily included in construction works of structures. Involving the dangers of collapse, large-scaled excavation walls require periodic deformation measurements. As only relative displacements and acquired and surface measurements can not be made with the conventional measuring methods, the up-to-date method which can overcome these weaknesses is required urgently. Terrestrial photogrammetry is the method by which absolute deformation amounts of many points can be taken out at a distance from object in short time. The objective of this study is to suggest application propriety of terrestrial photogrammetry to the measurement of excavation walls. For it, we devised same position photography(S.P.P) and possibility of SPP proved through basic experiment. SPP was very speedy photographing method. We found out the fact that as the degree of overlap increase, accuracies of results increase. As a result of applying to excavation side-wall, we detected consistent displacement in 3 dimension each direction within the limits expectional accuracy. If control surveying could be carried out more quickly and accurately, the deformation displacement could be analyzed more effectively.

• Journal of the Korea institute for structural maintenance and inspection
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• v.7 no.3
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• pp.215-222
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• 2003

Recently the deep and large excavations are performed near the existing buildings in urban areas for the practical use of underground space. The earth pressure due to the excavation are varied according to the conditions of ground, the depth of excavation, the construction methods, and the method of supporting the earth pressure etc.. In this study, not only the behavior of axial load and distribution of earth pressure on the flexible wall according to stage excavation depth but also magnitude and distribution of lateral deformation, and the equivalent earth pressure from strut axial loads were analyzed by the results measured from instruments such as, load cells, strain gauges, and in-situ inclinometer, on the field of subway construction. According to the results of this study in the case of stage excavation the earth pressure of soft clayey soil is compounded with Terzaghi-Peck and Tschebotarioff.

• Journal of the Korean Geotechnical Society
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• v.23 no.10
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• pp.121-131
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• 2007

This study is to investigate the damage assessment of adjacent structures due to excavation in urban environment. Model tests were carried out for 2 story masonry building and frame structures in various shapes and locations. The damage level of adjacent structures were very differently estimated in accordance with the shape ratio (L/h) of structures, construction stages, and various locations. Therefore the most weak part (bay) of structure must be heavily instrumented and monitored in more details at early stage of constructions. The progressive crack development mechanism at various construction stages was revealed through model tests and crack size indicated more conservative side of damage level on the damage level graph.

• Journal of the Korean Geotechnical Society
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• v.24 no.10
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• pp.25-32
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• 2008

Based on recent studies, the side resistance of rock socketed drilled shafts was affected by unconfined compressive strength of rock, socket roughness, rock types and joints, and initial normal stress. Especially, the socket roughness was affected by rock types and joints, drilling methods, and diameters of pile. In this study, a new roughness measurement system (BKS-LRPS, Backyoung-KyungSung Laser Roughness Profiling System) usable in water was developed. Based on the laboratory model tests, an EMD (Effective Measurement Distances) according to various turbidity was proposed as $EMD=1149.2{\times}T_{b}^{-0.64}$.

• The Journal of the Convergence on Culture Technology
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• v.10 no.1
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• pp.559-563
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• 2024

Currently, in Korea, large-scale, deep excavations are being carried out adjacent to structures due to overcrowding in urban areas. for adjacent excavations in urban areas, it is very important to ensure the safety of earth retaining structures and underground structures. accordingly, an automated measurement system is being introduced to manage the safety of subway tunnel structures. however, the utilization of automated measurement system results is very low. existing evaluation techniques rely only on the maximum value of measured data, which can overestimate abnormal behavior. accordingly, in this study, a vast amount of automated measurement data was analyzed using the Gaussian probability density function, a technique that can quantitatively evaluate. highly reliable results were derived by applying probabilistic statistical analysis methods to a vast amount of data. therefore, in this study, the safety evaluation of subway tunnel structures due to adjacent excavation work was performed using a technique that can process a large amount of data.

• The Journal of the Convergence on Culture Technology
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• v.10 no.1
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• pp.579-584
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• 2024

Currently, large-scale, deep construction is being carried out adjacent to subway tracks in korea. when excavating adjacent to each other, it is very important to ensure the safety of earth retaining structures and underground structures. therefore, we are managing the safety of the subway by introducing an automated measurement system. deformation of the subway track during adjacent excavation may affect train running stability. this is a factor that can be linked to train derailments. however, current subway track safety evaluation using automated measurement systems relies only on the maximum value of measured data. therefore, a method to improve the usability of automated measurement system results is needed. in this study, we utilized a technique that can quantitatively evaluate the measurement results of a large amount of subway track deformation. a safety evaluation was conducted on subway track deformation due to adjacent excavation using a vast amount of data using probabilistic statistical analysis techniques.

• Proceedings of the KSEE Conference
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• 2006.10a
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• pp.55-66
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• 2006

일반적으로 현장에서의 발파공법의 적용은 보안물건과 발파지점의 거리로 구분하여 설계한 종례의 방법에서 탈피하여 건설교통부에서 보안시설건물의 거리${\sim}$지발당장약량을 기초로 한 6가지의 타입으로 표준화한 방법을 제시하였다. 이는 시험발파를 통하여 발파공해 허용 기준치를 확보하고 회귀분석을 통한 발파영향권을 분석한 후 이격거리별 발파패턴 및 발파공법을 선정 및 설계를 기본으로 하는 것이며 이번 00대학교 민석도서관 건립공사에서 적용하여 타당성을 검토하여 실제 설계 시 적용을 하였으며 6 가지 타입의 기초적인 모델링을 기본으로 하여 시공설계 및 계측결과를 분석하였다.