• Title/Summary/Keyword: 터널 지보패턴

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A study on the optimization of tunnel support patterns using ANN and SVR algorithms (ANN 및 SVR 알고리즘을 활용한 최적 터널지보패턴 선정에 관한 연구)

  • Lee, Je-Kyum;Kim, YangKyun;Lee, Sean Seungwon
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.24 no.6
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    • pp.617-628
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    • 2022
  • A ground support pattern should be designed by properly integrating various support materials in accordance with the rock mass grade when constructing a tunnel, and a technical decision must be made in this process by professionals with vast construction experiences. However, designing supports at the early stage of tunnel design, such as feasibility study or basic design, may be very challenging due to the short timeline, insufficient budget, and deficiency of field data. Meanwhile, the design of the support pattern can be performed more quickly and reliably by utilizing the machine learning technique and the accumulated design data with the rapid increase in tunnel construction in South Korea. Therefore, in this study, the design data and ground exploration data of 48 road tunnels in South Korea were inspected, and data about 19 items, including eight input items (rock type, resistivity, depth, tunnel length, safety index by tunnel length, safety index by rick index, tunnel type, tunnel area) and 11 output items (rock mass grade, two items for shotcrete, three items for rock bolt, three items for steel support, two items for concrete lining), were collected to automatically determine the rock mass class and the support pattern. Three machine learning models (S1, A1, A2) were developed using two machine learning algorithms (SVR, ANN) and organized data. As a result, the A2 model, which applied different loss functions according to the output data format, showed the best performance. This study confirms the potential of support pattern design using machine learning, and it is expected that it will be able to improve the design model by continuously using the model in the actual design, compensating for its shortcomings, and improving its usability.

Evaluation of Support Performance of Fiber-Net Integrated Shotcrete in Tunnel Support System (숏크리트용 섬유 그물망 일체형 터널 지보시스템의 지보 성능 평가)

  • Kim, Jiyoung;Choi, Seongcheol
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.8 no.4
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    • pp.545-552
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    • 2020
  • This study evaluated the support performance of fiber-net integrated shotcrete in tunnel support system developed for the purpose of improving constructability and stability while fully performing its mechanical performance as a tunnel support materials by four-point bending test, two-dimensional numerical analysis, and cross-sectional analysis. As a result of evaluating the flexural performance through a four-point bending test, in the case of fiber-net reinforced shotcrete, the tensile performance of fiber-net resulted in a continuous increase in load after crack occurrence, unlike steel fiber reinforced shotcrete. Also, the results of the tunnel cross-sectional structure analysis for ground conditions and the cross-sectional analysis of fiber-net and steel fiber reinforced shotcrete showed that sufficient support performance can be exhibited even if the thickness of fiber-net reinforced shotcrete was reduced compared to the previous one. Additionally, through these results, the support pattern of fiber-net integrated shotcrete in tunnel support system, which can be applied efficiently to the construction sections requiring higher stability among the rock mass class III, was proposed.

A tunnel rock mass classification technique and its applicability using electrical resistivity and seismic wave velocity (전기비저항 및 탄성파속도를 이용한 터널암반의 정량적 평가수법과 적용성)

  • Park, Sam-Gyu;Kim, Jung-Ho;Cho, Seong-Jun;Yi, Myeong-Jong;Son, Jeong-Sul
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.5 no.3
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    • pp.291-299
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    • 2003
  • Electrical resistivity prospecting has been recently increased in the application to tunnel, landslide and other investigations in the civil engineering field. Therefore, it is essential to establish the rock mass classification technique using electrical resistivity data. In this paper, the authors, try to propose a technique which can classify tunnel rock mass using seismic wave velocities derived from electrical resistivity data. In addition, the applicability of the proposed tunnel rock mass classification technique is discussed, by comparing estimated support patterns with actually performed ones.

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A Study on Quantity of Shotcrete Sprayed in a NATM Tunnel Based on Field Measurements (현장 실측자료 분석을 통한 NATM 터널의 숏크리트 투입량에 관한 연구)

  • Lee, Cheol Ju
    • Journal of the Korean GEO-environmental Society
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    • v.12 no.9
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    • pp.47-54
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    • 2011
  • This study has analysed overbreaks, shotcrete rebound and the ratio between the actual quantity of shotcrete sprayed compared to designed quantity measured during a NATM tunnel construction. Based on the measurements of size of the excavated tunnel faces, an average overbreak was about 28.5 cm, which is about 260% of allowable overbreak. The measured shotcrete rebound was about 7.2% in average which is about half the allowable rebound(15%). In addition, due to overbreaks and rebound the actual quantity of shotcrete used in the tunnelling work was about 116.5 % of the designed value. It has been found from the field measurements that the quantity of shotcrete showed some relation with rock mass rating(RMR) and the standard guideline of tunnel supports, but the size of overbreak showed less correlation with RMR and the standard guideline of tunnel supports. Hence, the current tunnel design specifications stating the size of overbreak based entirely on the standard guideline for tunnel supports should perhaps be reestablished. The insight into the design guideline regarding overbreak and actual quantity of shotcrete will be reported and discussed.

Rationalization of Gripper TBM Supporting System Pass through Serviced Subway Line (기존 운행선 직하부 통과 굴착에 따른 Gripper TBM 지보패턴 합리화 방안)

  • Hak-Young So;Kook Hwan Cho
    • Tunnel and Underground Space
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    • v.34 no.4
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    • pp.413-420
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    • 2024
  • When planning gripper TBM, which is highly applicable to urban areas, the excavation characteristics are not considered. In addition the excavation stability and constructability are degraded by installing reinforcements in the adjacent construction site considering the relaxation load theory of the pre-existing NATM. In this study, a rationalization plan for the support was proposed considering the excavation characteristics of gripper TBM when planning reinforcements for adjacent pre-existing construction. The effect of excavation on the surrounding ground was analyzed by conducting three-dimensional stability analyses considering the construction stage for each excavation phase. In NATM, relaxation phenomenon is concentrated in tunnel face due to non-supporting time occurring simultaneously with excavation, but gripper TBM supports the ground around the tunnel face through the cutter head and skin plate, simultaneously causing ground relaxation behind the skin plate. Considering these excavation characteristics, problems in reinforcement planning for adjacent construction at the study site were pointed out. A performance improvement plan for a reasonable supporting system was proposed.

Evaluation of Support Requirements for the Single Shell Tunnels from the Case Study of Rock Mass Classifications (국내 암반분류 사례를 통한 싱글쉘 터널 지보량 산정 연구)

  • Kim Hak-Joon;Lee Seong-Ho;Shin Hyu-Seong;Bae Gyu-Jin
    • The Journal of Engineering Geology
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    • v.16 no.3 s.49
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    • pp.283-291
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    • 2006
  • Shotcrete is used as a permanent lining in single shell tunnels even though shotcrete has been used as a temporary lining in NATM tunnels. Therefore, the accurate evaluation of strength parameters is very crucial because the reliable estimation of loads acting on the shotcretes is necessary to maintain the stability of tunnels. The evaluation of strength parameters of the ground far the single shell tunnels should be investigated to adapt the method in Korea because the geological condition of Korea is different from that of other country. Rock classification and strength parameters obtained from 25 tunnel sites were investigated for this study. Support types fur the different rock classes are suggested for the single shell tunnels in Korea based on the NMT because Q-system has been widely used in Korea. The support types in terms of both Q and RMR values are given based on the correlation of Q and RMR values obtained from the case studies.