exploration and verification of tunnel stability evolution law under jointed rock mass with various attitudes

Studies show that weak structural faces in jointed rock masses can easily result in large deformations in tunnels, which significantly affect the safety and stability of supporting structures. to address this issue, the present study considers the linpanshan tunnel in a layered joint stratum as the case study, focusing on joint inclination and joint spacing. numerical simulations and field monitoring were conducted to investigate the displacement and stress evolution in the surrounding rock and tunnel structure under various attitudes of the jointed rock mass. the results indicate that the stability of surrounding rock and tunnel structures is more influenced by joint inclination than joint spacing. the maximum surrounding rock displacement reaches its maximum value, measuring 1.889 mm, for the joint attitude of 0° + 0.5 m; the maximum shear stress occurs at the right arch foot of the lining and reaches 11.44 kpa under the 60° + 1.5 m joint attitude. when joint inclination varies within the range of 0–60°, the rock formations slide significantly along the structural faces, leading to higher tensile stresses on the arch apex, arch spandrels, and arch feet of the lining. consequently, the tunnel structure becomes prone to asymmetric deformation and cracking. the present study analyses the deformation mechanism in surrounding rock and the cracking of lining structures in the 55° joint formation by incorporating the characteristics of the lining cracks in the linpanshan tunnel. as a reinforcement measure, the installation of additional anchors in the weak zone of the lining was proposed. meanwhile, the performance of the proposed technique was verified through field monitoring data. the research results provide a technical reference for large deformation control in jointed rock masses. © the author(s), under exclusive licence to the iran university of science and technology 2023.