Impact Of Rigid Structural Plane On Stability Of Deep Buried Hard Rock Tunnel

In China, more and more long-large-deep tunnel appears, even tunnel group, people pay attention to the stability of deep buried hard rock tunnel under the control of rigid structural plane day by day. Using the finite element analysis software Midas/GTS, this paper simplified excavation into plane strain problem, analyzed the influence of structural plane on the stability of tunnel with different lithology& high crustal stress conditions and its own characteristics, made a simulation experiment about size effect of structural plane under geostatic stress, as well as analyzed quantitatively the effects of rigid structural plane on the surrounding rock deformation and plastic zone with different conditions. This study has the certain reference value in the practical work.From the research, the following conclusions were achieved:(1) according to the surrounding rock deformation as the main index, the important data was obtained, including the maximum impacted distance and the effective impacted distance of rigid structural plane influence deep buried hard rock tunnel, as well as its characteristics changes impact on the surrounding rock deformation; (2) through the analysis of structural plane effects on the stability of tunnel with lithology changes, we can see good lithology reduces the adverse effect; conversely, weak lithology enhances the adverse effect; in the separately analysis of lithologic parameters, we found that tensile strength of rock mass has no effects on structural plane, while elasticity modulus, internal friction angle and cohesive force affect the structural plane in their own ways;(3) analysis of the effects of structural plane with different high crustal stress conditions shows that the instability of tunnel will be aggravated when side pressure coefficient k0 or geostatic stress increasing; (4) this study obtained the most unfavorable layout of small size structural plane in certain dip angle and distance and put forward the concept of the maximum effective impacted size; through analyzing the size effect of structural plane with high crustal stress and hard rock, the relationship among the maximum effective impacted size, dip angle and distance in the the effective influence distance was obtained, at last the size effect formulas were derived by curve fitting when 0°,45°nd 90°structural planes are apart from the tunnel 1 metre.