Quantitative analysis of the influence of bedding planes on the deformation of layered carbonaceous slate around tunnel

Because of the effect of bedding planes, inaccuracy deformation prediction for thin-layered rock often results in severe damage to the tunnel support in high in situ stress zone. For deformation prediction of layered rock, a series of numerical simulations using a continuum-interface numerical model were conducted to investigate the influences of the bedding planes on tunnel deformation. The feasibility of the numerical model is first verified by the comparisons of deformation and failure behaviors of layered rock between numerical results and field observations. Then, according to the numerical results, a deformation prediction equation considering effect of bedding planes was proposed for layered carbonaceous slates. The application of proposed deformation prediction equation showed that when the bedded thickness exceeds 0.05 m, the relative errors between the prediction deformation and observed deformation are less than 10%, which can satisfy the requirement of engineering applications. While, when the bedded thickness is less than 0.05 m, the proposed prediction equation cannot be used directly due to underestimation of the deformation of layered rock.