• Journal of Korean Tunnelling and Underground Space Association
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• v.15 no.2
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• pp.113-122
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• 2013

Recently there has been increased interest for the portal and shallow tunnel for an eco-friendly tunneling method. Semi cut & cover tunnel excavation techniques applied to concrete slab and construction and a growing number of cases, but there is no load combinations and arch concrete cross section for the applicable standards. Therefore, in this study, ground conditions and tunnel overburden thickness, thickness of backfill, overburden surface slope angle changes to a variety of conditions in order to propose standards for the semi cut & cover method was performed numerical analysis. Regression analysis method to the analysis of the results of numerical analysis, and linear regression equations derived to classify and organize a rational, economical, and safe semi cut & cover tunneling method based proposed.

• Tunnel and Underground Space
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• v.15 no.3 s.56
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• pp.177-184
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• 2005

The Sapaesan tunnel, the longest twin tube tunnel (4km) in Korea with 4 lanes each, is under construction with two years of delayed schedule because of the strong opposition from environmental bodies. Therefore, maximizing the construction efficiency was needed in tunnel project to compensate for time delay. This study includes improvements in the construction of the Sapaesan tunnel such as increasing excavation length and changing excavation sequence. In this paper the system for predicting tunnel face ahead is also introduced. Bulk-Emulsion explosive and Cylinder-Cut method were adopted in tunnel blasting to increase the excavation length. Optimum tunnel excavation step was designed to make up delayed time. Tunnel foe mapping, TSP survey and geological prediction system using computerized jumbo-drill were performed fnr safe construction of long and large twin tube tunnel.

• Tunnel and Underground Space
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• v.31 no.4
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• pp.211-220
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• 2021

Tunnel collapse often occurs during deep underground tunneling (> 40 m depth) in South Korea. Natural cavities as well as water supply pipes, sewer pipes, electric power cables, artificial cavities created by subway construction are complexly distributed in the artificial ground in the shallow depths of the urban area. For deep tunnel excavation, it is necessary to understand the properties of the ground which is characterized by porous elements and various geological structures, and their influence on the stability of the ground. This study analyzed geological factors for risk assessment in deep excavation in South Korea based on domestic and overseas case study. As a result, a total of 7 categories and 38 factors were derived. Factors with high weights were fault and fault clay, differential stress, rock type, groundwater and mud inrush, uniaxial compressive strength, cross-sectional area of tunnel, overburden thickness, karst and valley terrain, fold, limestone alternation, fluctuation of groundwater table, tunnel depth, dyke, RQD, joint characteristics, anisotropy, rockburst and so forth.

• Explosives and Blasting
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• v.21 no.3
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• pp.61-71
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• 2003

최근 도심지 굴착공법 선정시 주변환경에 대한 관심이 높아지면서 민원발생을 감안하여, 발파공법이 아닌 기계굴착공법(TBM, SHIELD 등) 등이 부분적으로 적용되고 있다. 그러나 이들 굴착공법들은 굴착조건의 변화에 따라 적용 한계성이 있고, 한계구간이 직면할시 시공성이 극히 떨어지거나 적용 자체가 불가능하게 된다. 이에 따라, 공사기간의 연장, 공사비의 증가 및 적용자체가 불가 할 경우는 공사중단에 이르게 되어 시공과정에서 다른 굴착공법으로 전환되는 사례가 빈번히 발생되고 있다. 따라서 본 사례는 도심지 터널구간으로 당초 할암공법으로 설계되었으나 암반의 강도가 높고 굴착단면적이 협소하여 할암공법이 적용될 수 없었다. 이에 대한 대안공법으로 TBM이나 기타 장비에 의한 기계굴착공법을 검토하였으나, 터널연장이 짧고 터널노선의 곡선부 반경이 작아 대형장비의 투입이 어려운 굴착조건 때문에 최종적으로 폭약을 이용한 발파굴착 공법을 선정하였다. 그러나 발파공법은 진동 및 소음이 필연적으로 수반되기 때문에, 주변 환경공해가 허용하는 범위 내에서 최대한의 시공성과 안전성 여부를 판단하기 위하여 발파진동 및 소음의 허용수준을 설정한 후 시험발파를 실시하였으며, 그 결과에 따라 진동제어발파공법을 적용하였다.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.115-120
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• 2003

In this study, smoke movement in tunnel fires was investigated with various aspect ratio(0.5, 0.667, 1.0, 1.5, 2.0) of tunnel cross section. Reduced-scale experiments were carried out under the Froude scaling using 8.27 kW ethanol pool fire. Temperatures were measured under the ceiling and vertical direction along the center of the tunnel. Smoke front velocity and temperature decrease rate were reduced as higher aspect ratio of the tunnel cross-section. Smoke movement was evaluated by analysis of vertical temperature distribution 3 m downstream from the fire source. Elevation of smoke interface according to N percent rule was under about 60% of tunnel height.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.1014-1019
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• 2003

It seems inevitable for residential buildings to be high-rise and allocated near traffic roads due to the overcrowding in urban area. Acoustic environment in those area has been seriously deteriorated by the increase of traffic vehicles. Commonly used sound barriers have a limitation in controlling noise due to diffraction noise of sound barrier. Hence sound barrier is not effective to attenuate noise especially for the residential units in high level. This work aims at evaluating noise reduction according to the tunnel section shape by using 1/5 scale model. We carried out a number of field measurements for 1/5 scale model of Noise Barrier Tunnel with various sectional shape. The results from predictions and the measurement show generally good agreement.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.8 no.6
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• pp.614-619
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• 1997

In this paper, radio-wave propagation characteristics in a rectangular corridor are investigated using a tunnel model of reduced dimensions. Measurements were carried out on vertical polarization characteristics in the frequency range from 2 GHz to 10 GHz. The experimental results for the propagation constant in tunnel model agree satisfactorily with theoretical prediction. It is shown that model method is applicable in determining the propagation characteristics in tunnel.

• Journal of Korean Tunnelling and Underground Space Association
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• v.8 no.4
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• pp.345-354
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• 2006

During installation of face bolts, they are often deviated from the designed horizontal direction. In this study, a laboratory test and numerical analysis were conducted to examine the change of support effect by them. Also, the number of bolts to be added for achieving the designed support effect was considered. It was verified in this study that the horizontal installation is more effective. Under the test condition of this study, 1.5 bolts/section should be added in the face of which the installation density was 3 bolts/section when the bolts were installed with $R15^{\circ}$ angle from the horizontal position.

• Journal of Industrial Technology
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• v.26 no.A
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• pp.17-28
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• 2006

In underground drilling and blasting, particularly in small headings(generally under $20m^2$), the prospects for changes of blast parameters are usually more limited than those employed by large area tunnel(over $20m^2$). It is also well known that the consumption of explosives and specific drilling rate for small tunnel areas are exponentially increased also tunnel areas decrease. To confirm above results, some tests for two tunnels(irrigation water tunnel with $6.0m^2$ area, electric supplies tunnel with $15.0m^2$) are also carried out in this study. As a results, specific drilling rate and specific charge for irrigation water tunnel were decreased from 13.8 to $7.7m/m^3$ and from 4.88 to $2.56kg/m^3$ respectively. Those for electric supplies tunnel were also decreased from 8.0 to $4.9m/m^3$ and from 3.46 to $2.22kg/m^3$.

• Journal of the Korean Geotechnical Society
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• v.18 no.1
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• pp.17-28
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• 2002

Tunnel construction is a complex three dimensional operation. Since, however, it is neither possible nor useful to simulate all conditions and parameters in detail, a simplified two dimensional model is commonly employed in practice. The simulation of three dimensional conditions by a two dimensional model should use empirical parameters. The numerical predictions indicate that analysis results are highly dependent on the parameters. An improved modelling method based on time was adopted to account for three dimensional effect at the tunnel heading and time dependent nature, and used to perform an analysis of tunnelling in decomposed granite. The effects of weathering degree, tunnel shape and multi-drift excavation were investigated by using the method. It is identified that a structural benefit can be obtained by adopting a horse-shoe-shaped cross section with multi-drift excavation in mixed-force ground condition.