Search

To investigate the stability of surrounding rock of bedding dolomite tunnels with different dip angles, this study considers the diversity of tunnels in different geological conditions. In the case of five different bedding angles, the effects of different dolomite rock thicknesses, contact interlayer thicknesses, contact interlayer elastic moduli, contact interlayer cohesive forces, and contact interlayer friction angles on tunnel stability are analyzed. When the bedding angle is 22.5°, the surrounding rock displacement is the largest, the peeling between layers is obvious. The plastic zone of the surrounding rock is concentrated in the unsupported area of the tunnel. The contact interlayer has a weakening effect on the displacement of the surrounding rock and the expansion of the plastic zone. The thickness of the dolomite and the thickness of the contact interlayer have different effects on the displacement of surrounding rock of different bedding angles. Increasing the elastic modulus of the contact interlayer can reduce the displacement of the surrounding rock, increasing the internal friction angle of the contact interlayer has less influence on the displacement of the surrounding rock, and increasing the cohesive force of the contact interlayer can reduce the displacement of the surrounding rock.

This study presents a theoretical solution on stress and displacement of the deep-buried tunnel surrounding rock in layered strata. Based on theory of Покровский equivalent layer method, we convert layered strata into homogeneous ones and then map the rectangular tunnel in the coordinate plane z to the unit circle of complex plane ζ, through using a complex variable method and calculating the analytic functions Φ(ζ) and Ψ(ζ) with Matlab, the study obtains that the stress of the surrounding rock of deep-buried rectangular tunnel in layered strata. Subsequently, we derive the strain and displacement of the surrounding rock. Finally, we study the effects of lateral pressure coefficient and grade of surrounding rock and height-to-width ratio of the tunnel on the stress of tunnel surrounding rock. Based on our analysis, we formulate valuable rules.