• Title/Summary/Keyword: shotcrete tunnel lining

Search Result 102, Processing Time 0.022 seconds

Analysis of Reinforcement Effect of TSL (Thin Spray-on Liner) as Supports of Tunnel by Numerical Analysis (수치해석에 의한 터널 지보재로서 TSL(Thin Spray-on Liner)의 보강 효과 분석)

  • Lee, Kicheol;Kim, Dongwook;Chang, Soo-Ho;Choi, Soon-Wook;Lee, Chulho
    • Journal of the Korean Geosynthetics Society
    • /
    • v.16 no.4
    • /
    • pp.151-161
    • /
    • 2017
  • A TSL (Thin Spray-on Liner) has a higher initial strength and faster construction time than conventional cementitious shotcrete. Because of its high adhesion and tensile strength, the TSL reinforced concrete show a characteristic like composite materials. In this study, to consider an application to the conventional design method, ASD (allowable stress design), numerical study was used. In the numerical analysis, material and contact properties were adopt from previous studies. Then a thickness of concrete in the tunnel was evaluated with the TSL reinforced case by the ASD concept. In other words, bending compressive stress, bending tensile stress and shearing force of the concrete were considered to determine a thickness of concrete lining by the given boundary conditions. From the numerical analysis, there was no tendency to show by the ASD because the ASD is based on the elastic theory while the TSL typically contributes to reinforcement after yielding.

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
    • /
    • v.24 no.6
    • /
    • pp.617-628
    • /
    • 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.