| Summary: | Although quasi-rectangular tunnels have been widely used in underground projects, there is no related research work that was carried out to design this kind of tunnel excavated in the rock masses that followed the Hoek–Brown (HB) criterion. By transforming the strength parameters of the rocks that obey the HB failure criterion into equivalent strength parameters of the Mohr–Coulomb (MC) criterion, the lining internal forces of a quasi-rectangular tunnel are investigated in this manuscript in light of bending moments and normal forces using the Hyperstatic Reaction Method (HRM). After comparing with the values of a model test and verifying the present method, the influence of different tunnel depths, <i>H</i>, different rock unconfined compressive strengths, <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>σ</mi><mrow><mi>c</mi><mi>i</mi></mrow></msub></mrow></semantics></math></inline-formula>, and the geological strength parameter GSI on the lining internal forces of the quasi-rectangular tunnel is then investigated. The obtained results indicate that the parameters <i>H</i>, <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>σ</mi><mrow><mi>c</mi><mi>i</mi></mrow></msub></mrow></semantics></math></inline-formula>, and GSI have a significant effect on the lining internal forces of the quasi-rectangular tunnel. The work presented in this paper provides a theoretical reference for designing the quasi-rectangular tunnel support structure built in the rock masses following the Hoek–Brown criterion.
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