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A quantitative approach to predict tunnel overbreak based on the Q-system

Author(s):


Medium: journal article
Language(s): English
Published in: IOP Conference Series: Earth and Environmental Science, , n. 1, v. 833
Page(s): 012165
DOI: 10.1088/1755-1315/833/1/012165
Abstract:

Overbreak can be a significant challenge in tunnelling and is usually assessed on a project-by-project basis. This paper attempts to quantify tunnel overbreak in jointed rock masses by producing a predictive model that practitioners can utilize at the preliminary design stage. Discontinuum numerical analysis of a circular-shaped tunnel is performed using the combined finite difference – discrete element method to generate a database of rock masses prone to overbreak. The Q-system, rock mass quality index, is used to classify the rock masses that are expected to overbreak in various tunnelling environments. The results are scrutinized to identify trends between overbreak and: i) Q, ii) average joint spacing and, iii) in-situ stress conditions. It is observed that overbreak increases when Q < 4 and is uniform when Q ≤ 4. A predictive model is generated through multiple regression analysis and can be used to identify and highlight the maximum likely overbreak or scenarios where overbreak is expected to occur.

License:

This creative work has been published under the Creative Commons Attribution 3.0 Unported (CC-BY 3.0) license which allows copying, and redistribution as well as adaptation of the original work provided appropriate credit is given to the original author and the conditions of the license are met.

  • About this
    data sheet
  • Reference-ID
    10780993
  • Published on:
    11/05/2024
  • Last updated on:
    05/06/2024
 
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