• Title/Summary/Keyword: Underground cable tunnel

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A Study on the Stratum Thickness Arrangement and Roof Bolt Support Design using Robust Design (강건설계를 이용한 층서두께 배열과 루프볼트 지보설계에 관한 연구)

  • Jang, Myoung Hwan
    • Tunnel and Underground Space
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    • v.28 no.2
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    • pp.142-155
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    • 2018
  • The ${\bigcirc}{\bigcirc}$ mine has irregularly developed stratum around the ore body. The purpose of this study is to array irregular stratum thickness systematically for effective roof bolting and to implement a supporting system corresponding to it. The number of 81 cases combined with stratum thicknesses was limited to 9 cases by robust design. For each case, the load height which can act as a roof load was determined by the characteristics of stratum and RMR. The load range due to the load height is calculated assuming block shaped and arch shape. The support load of the roof bolt was considered as the average load of the two methods. Numerical analysis results of the support design showed that the cable bolt was more effective for the roof supporting fully grouted than the anchoring type. As a result of the construction, it was possible to control the roof, but all of the roof was gradually sinking downward due to the deformation of the side wall of the mine tunnel.

Refurbishment of a 3.6 m earth-pressure balanced shield TBM with a domestic cutterhead and its field verification (국산 커터헤드를 장착한 직경 3.6 m 토압식 쉴드TBM의 제작과 현장적용성 분석)

  • Bae, Gyu-Jin;Chang, Soo-Ho;Choi, Soon-Wook;Kang, Tae Ho;Kwon, Jun-Yong;Shin, Min-Sik
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.17 no.4
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    • pp.457-471
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    • 2015
  • A domestic cutterhead with the diameter of 3.6 m was designed and manufactured in this study. Then, it was attached to an existing earth-pressure balanced shield TBM to excavate a cable tunnel with the length of 1,275 m. Especially, the procedures for TBM cutterhead design and its corresponding performance prediction were also summarized. From field data analyses of the refurbished shield TBM, its maximum advance rate was recorded as 14.4 m/day. Penetration depths of disc cutters were found to be approximately 4 mm/rev, which is equal to the maximum penetration depth designed for the strongest rock strength condition in the target tunnel. Every TBM operating thrust and cutter normal force during TBM driving was much smaller than their corresponding maximum capacities. When cutter acting forces recorded in the field were analyzed, their prediction errors by the CSM model were very high for weak rock conditions. In addition, rock strength showed very close relationships with cutter normal force and penetration depth.

A study on the establishment of domestic criteria through analysis of shield TBM requirements in overseas ITB (Invitation to Bid) (해외 쉴드TBM 입찰안내서 분석을 통한 국내 발주 기준 정립에 관한 연구)

  • Kim, Ki-Hwan;Kim, Hyouk;Mun, Cheol-Hwa;Kim, Young-Hyu;Kim, Dong-Ho;Lee, Jae-Yong
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.19 no.6
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    • pp.985-997
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    • 2017
  • In many countries, most of the tunneling works have been ordered by the shield TBM, and also Korean companies are actively bidding and execute in this project. In case of Korea, refurbished machines are mainly using in power cable, gas pipelines, and water and sewage tunnel. Also in metro projects, shield TBM of over diameter 7m is required mainly by using brand new machine. Since the shield TBM is not easy to change once it is produced, it is necessary for the client to provide sufficient information on the production conditions so as to satisfy various characteristics of the construction. In this study, to manufacturing optimal shield TBM, the Client's TBM requirements of tunnel construction in Hong Kong and UK was analyzed and compared with the domestic requirements. The results are expected to provide as client's guidelines for bidding stage and manufacturing for shield TBM tunneling in Korea in the future.

Analysis of Induced Voltage on the Gas Pipeline at the Fault in a Underground Power Cables (지중전력케이블에서 고장발생시 인근 가스배관에 유도되는 전압 해석)

  • Bae J. H.;Kim D. K.;Kim K. J.
    • Journal of the Korean Institute of Gas
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    • v.4 no.3 s.11
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    • pp.26-32
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    • 2000
  • Because of the continuous growth of energy consumption, and also the tendency to site power lines and pipelines along the same routes, the close proximity of high voltage structures and metallic pipelines has become more and more frequent. Moreover, normal steady state and fault currents become higher as electric networks increase in size and power Therefore, there has been and still is a growing concern(safety of people marking contact with pipeline, risk of damage to the pipeline coating, the metal and equipment connected to pipeline, especially cathodic protection system) about possible hazards resulting from the influence of high voltage power system on metallic structures(gas pipeline, oil pipeline and water pipeline etc.). Therefore, we analyze the interference problems when the gas pipeline is buried with power cable in the same submarine tunnel. This paper present the results of the study about interference mechanism, AC corrosion limitation of safety voltage and analysis of induction voltage.

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An Experimental Study on the Fire Monitoring System for Tunnel Using SMA and Fiber Optic Cable (형상기억합금과 광케이블을 이용한 터널의 화재감지 시스템 개발에 관한 실험적 연구)

  • Hwang, Ji-Hyun;Park, Ki-Tae;Lee, Kyu-Wan
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.18 no.5
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    • pp.128-134
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    • 2014
  • Recently, design and construction of street tunnels tend to focus on cost reduction and preservation of nature. Accordingly, research is actively being carried out to quickly detect fires when they occur in tunnels, which have partially closed structures. Among such research, fire detection methods using optical fiber sensors have a wide bandwidth and fast transmission speed, while using light as a medium. Therefore, it does not receive electrical interference and there is almost no loss of information during transmission, while also having little noise as well. In relation to this, a fire monitoring system that can accurately detect the location of fires in real time using shape memory alloy and optical cables was developed in this study. In order to verify the developed method, light loss measurement test was conducted according to indoor temperature changes, while also conducting fire simulation tests by installing test beds in common underground zones with different external environments of temperature and distance. Upon carrying out experiments, the fire monitoring system developed in this study was found to be able to detect fires in long distance sections in real time.

A study on the utilization of abrasive waterjet for mechanical excavation of hard rock in vertical shaft construction (고강도 암반에서 수직구 기계굴착을 위한 연마재 워터젯 활용에 관한 연구)

  • Seon-Ah Jo;Ju-Hwan Jung;Hee-Hwan Ryu;Jun-Sik Park;Tae-Min Oh
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.25 no.5
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    • pp.357-371
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    • 2023
  • In cable tunnel construction using TBM, the vertical shaft is an essential structure for entrance and exit of TBM equipment and power lines. Since a shaft penetrates the ground vertically, it often encounters rock mass. Blasting or rock splitting methods, which are mainly used to the rock excavation, cause public complaints due to the noise, vibration and road occupation. Therefore, mechanical excavation using vertical shaft excavation machine are considered as an alternative to the conventional methods. However, at the current level of technology, the vertical excavation machine has limitation in its performance when applied for high strength rock with a compressive strength of more than 120 MPa. In this study, the potential utilization of waterjet technology as an excavation assistance method was investigated to improve mechanical excavation performance in the hard rock formations. Rock cutting experiments were conducted to verify the cutting performance of the abrasive waterjet. Based on the experimental result, it was found that ensuring excavation performance with respect to changing in ground conditions can be achieved by adjusting waterjet parameters such as standoff distance, traverse speed and water pressure. In addition, based on the relationship between excavation performance, uniaxial compressive strength and RQD, it was suggested that excavation performance could be improved by artificially creating joints using the abrasive waterjet. It is expected that these research results can be utilized as fundamental data for the introduction of vertical shaft excavation machines in the future.

Fabrication of Three-Dimensional Scanning System for Inspection of Mineshaft Using Multichannel Lidar (다중채널 Lidar를 이용한 수직갱도 조사용 3차원 형상화 장비 구현)

  • Soolo, Kim;Jong-Sung, Choi;Ho-Goon, Yoon;Sang-Wook, Kim
    • Tunnel and Underground Space
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    • v.32 no.6
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    • pp.451-463
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    • 2022
  • Whenever a mineshaft accidentally collapses, speedy risk assessment is both required and crucial. But onsite safety diagnosis by humans is reportedly difficult considering the additional risk of collapse of the unstable mineshaft. Generally, drones equipped with high-speed lidar sensors can be used for such inspection. However, the drone technology is restrictively applicable at very shallow depth, failing in mineshafts with depths of hundreds of meters because of the limit of wireless communication and turbulence inside the mineshaft. In previous study, a three-dimensional (3D) scanning system with a single channel lidar was fabricated and operated using towed cable in a mineshaft to a depth of 200 m. The rotation and pendulum movement errors of the measuring unit were compensated for by applying the data of inertial measuring unit and comparing the similarity between the scan data of the adjacent depths (Kim et al., 2020). However, the errors grew with scan depth. In this paper, a multi-channel lidar sensor to obtain a continuous cross-sectional image of the mineshaft from a winch system pulled from bottom upward. In this new approach, within overlapped region viewed by the multi-channel lidar, rotation error was compensated for by comparing the similarity between the scan data at the same depth. The fabricated system was applied to scan 0-165 m depth of the mineshaft with 180 m depth. The reconstructed image was depicted in a 3D graph for interpretation.