LAUSR

Abstract Circular tunnels are usually encountered when excavating in weak soil medium at shallow depth and using shield machines. However, special shaped tunnels such as squared tunnels and sub-rectangular tunnels are also recently used to improve the efficiency of underground space use. This paper focuses on improving the performance of the Hyperstatic Reaction Method (HRM), which is a numerical method, for the case of squared or sub-rectangular tunnels. Special attention is paid to the tunnel shape influence by using various tunnel wall radii. The numerical HRM model was validated based on a comparison with the finite element method (FEM). The results indicated that HRM can be effectively used to estimate the behavior of squared or sub-rectangular tunnels. Then a parametric study was conducted to highlight the influence of the earth pressure coefficient and of the soil Young’s modulus on the structural forces, and deformations induced by the excavation in the tunnel lining.