• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.980-987
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• 2006

Recently, twin-tunnel is often designed considering the aspects of disaster prevention and economic reasons. However, the design cases and the studies are relatively insufficient. By the twin-tunnel excavation, deviate stresses of pillar between tunnels are increased and the increased stresses induce the instability of the twin-tunnel. In this study, numerical analyses about the twin-tunnel behaviour are conducted while varying ground strength, width of pillar and depth of earth cover and a series of regression analyses are carried out by using the results of numerical analyses for the twin-tunnel. Based on the numerical analyses, an estimation method of derived stresses is suggested though the regression analyses. Also, based on the results of regression analyses, an quantitative estimation method considering the reinforcement effects is also suggested. Then various parametric studies are conducted to be considered the reinforcement type and various design parameters. Finally, the efficiency of the suggested method is verified through the results of parametric studies.

• Tunnel and Underground Space
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• v.33 no.3
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• pp.141-149
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• 2023

Recently, as the demand for urban underground space increases, urban tunnel planning is actively progressing. In particular, the application of the roadheader excavation method, which has favorable applicability to urban tunnel, is increasing. However, it is known that the roadheader excavation method has a limitation in that excavation efficiency for high strength rock with a Uniaxial Compressive Strength (UCS) of 100 MPa or more is lowered. In this study, The pre-cracked method was presented as a method to improve the excavation efficiency of roadheader for high strength rock and its applicability was evaluated. The net cutting rate was evaluated using the Bilgin prediction formula, which can calculate the net cutting rate by considering the UCS and RQD (Rock Quality Designation). It was found that the net cutting rate increased as the RQD decreased under the rock condition with the same UCS. This is judged to increase the excavation efficiency of the roadheader in the jointed high strength rock. Additionally, the field applicability of the pre-cracked method for high strength rock was verified through field tests. It was confirmed that the crack zone was formed around the charging hole, and it is considered that the pre-cracked method can be applied to the high strength rock.

• Journal of Korean Tunnelling and Underground Space Association
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• v.11 no.2
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• pp.107-115
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• 2009

Lately, the length of tunnel, the number of large-long tunnel over three lanes are steeply increased because of the request for high speed and straight road. Therefore, the maximization of excavation efficiency is needed in tunnel construction. Bulk Emulsion explosives charging system is the spearhead equipment using the radio remote control $&$ mechanization system compare with a traditional method Cartridge type. This study introduced the bulk emulsion explosives which is new method in tunnel blasting and verified the efficiency of bulk emulsion explosives for long-large tunnel. And we tried to compare Cartridge type efficiency with bulk emulsion explosives efficiency by the field test.

• Journal of Korean Tunnelling and Underground Space Association
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• v.15 no.1
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• pp.49-57
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• 2013

The conventional blasting method generates serious blasting vibration and underbreak/overbreak in spite of its high efficiency for rock excavation. To overcome these disadvantages, this paper introduces an alternative excavation method that combines the conventional blasting process with the free surface on the perimeter of the tunnel face using waterjet cutting technology. This proposed excavation method has advantages of (1) reducing vibration and noise level; (2) minimizing underbreak and overbreak; and (3) maximizing excavation efficiency. To verify the effects of the proposed excavation method, field tests were performed with a smooth blasting method at the same excavation conditions. Test results show that the vibration is reduced by up to 55% and little underbreak/overbreak is generated compared with the smooth blasting method. In addition, the excavation efficiency of the proposed method is greater than that of the smooth blasting method. The proposed blasting method with a free surface using waterjet cutting can be applied to urban excavation construction as well as to underground structure construction.

• Proceedings of the KSR Conference
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• 2005.11a
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• pp.412-417
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• 2005

To ensure the safety of the tunnelling without the loss of economy, the tunnel seismic profiling(TSP) method for the prediction ahead of tunnel face, begins to be used routinely in these days. TSP method does not interfere the tunnelling works while the horizontal drilling does, and its prediction length is longer than that of the drilling. Yet the most frequently adopted technique of TSP in Korea is the multi-shot and 2 receiver array using in-hole receivers, even though this array requires as many as 26 drill-holes for receiver installation and ballasting, which results in 3-6 hours of suspension in excavation work. In this paper, multi-receiver and lesser shot array using side-wall attached 3 component geophones is to be described to prove the efficiency in terms of the survey time as well as the reliability of the method by comparison of the predicted weak points and the face mapping results. The predictions mostly agreed with the real fractures or joint developed zones which have been confirmed during the excavation. It also has been found that TSP method can be effectively applied to perform draining ground water ahead of tunnel face by imaging the geologic discontinuities.

• Geotechnical Engineering
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• v.11 no.1
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• pp.51-62
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• 1995

The use of TBM has been rapidly increased in recent years since TBM has been introduced to Korea in 1985 and Korea came to occupy 27% of TBM holding ratio in the world. Despite a lot of experience, study on promoting the efficiency of TBM excavation is insufficient. The factors that influence the efficiency of excavation are the mechanical farttor geotechnical factor and management factor. The study on the efficiency of excavation has focused on the improvement of mechanical factor. But geotechnical factor is also very important and by this factor engineer can estimate the applicability of TBM. The purpose of this paper is to understand the effectiveness of TBM excavation for vari orts rock quality by analysing relations between rock quality and TBM excavation.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.4
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• pp.242-247
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• 2017

Over- and under-excavation are factors that increase construction cost of tunnels, which makes management essential. Total stations have been used for tunnel surveying because GNSS is difficult to use in tunnels. However, it takes much time to acquire data using total stations. In this study, a total station was integrated with a 3D laser scanner and used for tunnel surveying in Namyangju-si, Gyeonggi-do. The scanning total station reduced the work time compared to the conventional method. Furthermore, reports were effectively generated for overbreak and underbreak for each section and compared with the design. In addition, we could analyze both the cross section and scanned area effectively by using the scanning data. This method can improve the efficiency of tunnel surveying work by combining the advantages of a conventional total station and a 3D laser scanner.

• Tunnel and Underground Space
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• v.5 no.1
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• pp.48-56
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• 1995

Recently, most of the underground excavation works are adopting heavy duty mobile diesel equipments which have outstanding merits in view of efficiency. However, these equipments are causing hygienic problems to the workers due to the various hazardous exhaust contaminants. Considering that there are always dead end workings in underground excavation sites, it is very important how to supply enough airflow to the workings to dilute diesel exhaust contaminants. This paper introduced the theoritical mechanism and actual trends of exhaust contaminants of diesel equipments under operation at local mines and suggested the design method of intake air volume in underground excavation workings using diesel equipments.

• Proceedings of the Korean Geotechical Society Conference
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• 2000.03b
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• pp.93-100
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• 2000

In this study, we used photoelastic coating method which is a kind of model test for examining the stress condition of rock masses around underground structures. Using this method, we could know adaptability and usefulness of photoelastic coating method for various shape of tunnel models. And, in spite of higher cross section efficiency, square shape model showed unstable status because of high stress concentration. So, we cut the slits at the each corner of tunnel, and we could make more stable stress condition by means of moving high stress concentration to rock mass.

• Journal of Korean Society for Geospatial Information Science
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• v.14 no.3 s.37
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• pp.31-37
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• 2006

The existing tunnel survey method contains many problems of taking much measuring time, increasing construction expenses, and delaying a term of construction. Therefore the site survey system for an improvement efficiency is developed. This system will be able to solve the ewer factor and the problem of curtailment of time and expenditure. In order to solve these problems it connected a measurement equipment and a notebook computer, and developed the system which simultaneously with tunnel measurement it will be able to decide locations and errors from site at real-time. The development or the tunnel survey system minimize the error occurrence as measuring tunnel, and the probability of more or less excavation. Therefore this site survey system leads to the effect of the improvement execution quality of work, the cost reduction and the construction term reduction.