An Analysis of Loess Tunnel Failure and Its Mechanism

A series of changes mechanical properties such as fracture development, relaxation, collapse deformation, and strength decreasing the surrounding rock loess tunnels occur due to shearing immersing, will be prone engineering failures, including large fissure, ground collapse, landslide, lining cracking, seriously threatening construction operation safety tunnels. These problems are especially prominent for long-span Based on understanding features in tunnel project proceeding from perspective structural evolution loess, distribution shear deformation zone, instability excavation face, adverse effects geological conditions, predisposing factors damage supporting structure large-span tunnels, common types their formation mechanisms analyzed this paper. According relationship between law change, an improved Mohr–Coulomb elastic-plastic, tension-compression-shear, constitutive model, considering property, is established applied numerical calculation. The mechanism different failures course revealed by analysis, which property strata, excavating actions simulated method. reference provided prevention remediation a tunnel.