让压层对大变形隧道喷混结构破坏模式及力学行为的影响研究OA

Aiming at the problem that traditional supporting structures are prone to failure in large deformation disasters of high-ground stress soft rock tunnels,this paper studies the influence of yielding layers on the primary failure mode and mechanical behavior of large deformation non-circular tunnels through numerical calculation methods.Based on the background of a tunnel engineering in southwest China,a numerical model is established that considers shotcrete damage and the three-linear mechanical characteristics of the yielding layer.A comparative analysis of the damage evolution,failure modes,and mechanical responses of the lining is conducted for three support schemes:conventional support,rigid support,and yielding support.The results demonstrate that,compared to increasing support thickness,the yielding support significantly delays the damage initiation in the primary support.Relative to the conventional scheme,the yielding layer increases the maximum axial force in the primary support by 82.6%and reduces the maximum bending moment by 37.5%,shifting the primary support's mechanical mechanism from being predominantly"bending-controlled"to"compression-controlled".Furthermore,the installation of the yielding layer alters the failure mode of the primary support from local failure to excessive deformation failure.