Abstract
The accurate characterization of in-situ stress states within rock masses is a critical prerequisite for the safe design and construction of road and railway tunnels. This paper synthesizes and extends the reservoir geomechanics framework developed by Zoback (2010, Stanford University) — originally conceived for petroleum wellbore applications — and rigorously adapts it to the problem of underground rock excavation in civil engineering contexts. The paper presents a new analytical methodology, the Integrated Stress Analysis Framework for Rock Tunnels (ISAF-RT), which combines in-situ stress characterization techniques (extended leak-off tests, hydraulic fracturing in pilot boreholes, wellbore breakout analysis) with classical rock mechanics tools (Kirsch analytical solution, Mohr-Coulomb and Hoek-Brown failure criteria, ConvergenceConfinement Method) within a unified probabilistic design workflow. The ISAF-RT framework introduces a novel six-phase sequential procedure that explicitly accounts for tectonic stress regime (normal, strike-slip, thrust faulting), anisotropic stress ratios (K₀), rock mass quality (GSI index), and time-dependent deformation, enabling the engineer to select appropriate support systems with quantified reliability. Application of the framework is demonstrated through numerical examples representative of Alpine railway tunnels and highway tunnels in folded mountain belts, where thrust-faulting regimes impose horizontal stresses up to 1.8 times the vertical overburden. The results highlight the importance of pre-excavation stress measurement campaigns and show that neglecting stress anisotropy can lead to underdesign of support by factors of 2-3. The ISAF-RT framework provides a rigorous, systematic, and practically applicable tool for geotechnical engineers engaged in subsurface infrastructure in challenging rock conditions.
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Published on 13/09/26
Licence: CC BY-NC-SA license
