Based on the Hoek-Brown strength criterion and geological strength index (GSI) surrounding rock rating system

rock strength weakening behavior is analyzed

a method to determine the rock peak and the peak strength parameters is summarized

a simplified calculation method for the strain-softening model is proposed. By using FLAC3D numerical simulation software

and based on convergence constraint method

the stability of surrounding rock and the support in buried large section tunnel are analyzed

and the safety factor for supporting structure is calculated. The results show that: with the release of the rock stress

rock softening parameter decreases and strength weakening behavior becomes severe. Although the high GSI (GSI = 75) for rock

strength weakening is serious

the deformation is still small. For low GSI (GSI = 25) of the rock showing the perfect elastoplastic behavior. The proposed simplified Hoek-Brown strain-softening model is suitable for the tunnel close to the rock section of the surrounding rock. The convergence constraint method is applied to analyzing the stability of surrounding rock and support

which could provide a reference for initial support to optimize the design and safety evaluation in tunnels.