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Geomechanics and Engineering
  Volume 21, Number 2, April25 2020, pages 201-206

Quantitative assessment of depth and extent of notch brittle failure in deep tunneling using inferential statistical analysis
Kang-Hyun Lee, In-Mo Lee and Young-Jin Shin

    A stress-induced brittle failure in deep tunneling generates spalling and slabbing, eventually causing a v-shaped notch formation. An empirical relationship for the depth of the notch to the maximum tangential stress assuming an equivalent circular cross-section was proposed (Martin et al. 1999). While this empirical approach has been well recognized in the industry and used as a design guideline in many projects, its applicability to a non-circular opening is worth revisiting due to the use of equivalent circular profile. Moreover, even though the extent of the notch also contributes to notch failure, it has not been estimated to date. When the estimate of both the depth and the extent of notch are combined, a practical and economically justifiable support design can be achieved. In this study, a new methodology to assess the depth as well as the extent of notch failure is developed. Field data and numerical simulations using the Cohesion Weakening Frictional Strengthening (CWFS) model were collected and correlated with the three most commonly accepted failure criteria (
Key Words
    deep tunneling; brittle failure; spalling; inferential statistical analysis
Kang-Hyun Lee: Research Institute, Korea Expressway Corporation, Hwaseong-si 18489, Korea

In-Mo Lee: School of Civil, Environmental and Architectural Engineering, Korea University, Seoul 02841, Korea

Young-Jin Shin: R&D Center, Hyundai Engineering & Construction, Seoul 03058, Korea

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