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<p>In the early stages of deep tunnel design, identifying potential hazards, such as significant deformations around the tunnel after excavation, is crucial. The abacus introduced by Hoek &amp; Marinos (2000) remains a widely used tool for estimating such deformations. This article aims to clarify the assumptions of the original abacus and updates it using numerical modeling, supplemented by a Monte Carlo simulation on input parameters to address a broader range of geological scenarios. Unlike the original approach based on analytical expressions, the new curves incorporate a generalized Hoek and Brown failure criterion, revised parameter intervals, and enhanced practical applicability. To address uncertainties in input parameters at early design stages, a “3-point method” was developed. This method propagates uncertainties through the updated curves, enabling the estimation of the median radial strain, a confidence interval—reasonably associated with a 95% range under certain assumptions—and the parameters of the probability density function. The method and updated curves were validated through a case study of the Yacambu–Quibor tunnel, demonstrating their effectiveness in estimating squeezing potential and uncertainty impacts. The updated curves offer three key advantages: (1) they eliminate the need to estimate the uncertain rock mass strength; (2) they account for variability in the elastic modulus using three modulus ratios (200, 400, 600); and (3) they rely exclusively on input parameters from laboratory tests and field investigations (σ<sub>ci</sub>, m<sub>i</sub>, σ<sub>0</sub>), with GSI iso-values introduced. These improvements provide a more reliable tool for assessing tunnel deformation risks while maintaining the qualitative recommendations of the original abacus.</p>

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Improved Squeezing Prediction of Deep Tunnels Within Highly Fractured Rock Mass: Update of the Hoek & Marinos Curve Under Uncertainties

  • 期刊论文

  • 发表日期：

    2025年4月29日

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  • B. Fenneteau,
  • O. Deck,
  • R. Mehdizadeh,
  • F. Laigle

摘要

In the early stages of deep tunnel design, identifying potential hazards, such as significant deformations around the tunnel after excavation, is crucial. The abacus introduced by Hoek & Marinos (2000) remains a widely used tool for estimating such deformations. This article aims to clarify the assumptions of the original abacus and updates it using numerical modeling, supplemented by a Monte Carlo simulation on input parameters to address a broader range of geological scenarios. Unlike the original approach based on analytical expressions, the new curves incorporate a generalized Hoek and Brown failure criterion, revised parameter intervals, and enhanced practical applicability. To address uncertainties in input parameters at early design stages, a “3-point method” was developed. This method propagates uncertainties through the updated curves, enabling the estimation of the median radial strain, a confidence interval—reasonably associated with a 95% range under certain assumptions—and the parameters of the probability density function. The method and updated curves were validated through a case study of the Yacambu–Quibor tunnel, demonstrating their effectiveness in estimating squeezing potential and uncertainty impacts. The updated curves offer three key advantages: (1) they eliminate the need to estimate the uncertain rock mass strength; (2) they account for variability in the elastic modulus using three modulus ratios (200, 400, 600); and (3) they rely exclusively on input parameters from laboratory tests and field investigations (σci, mi, σ0), with GSI iso-values introduced. These improvements provide a more reliable tool for assessing tunnel deformation risks while maintaining the qualitative recommendations of the original abacus.