Three-Dimensional Elastoplastic Analysis on the Stability of Tunnel Anchorage in Soft Rock

Based on the physical and mechanical properties test results of tunnel anchorage′s surrounding rock, geological conditions, mechanical parameter analysis and mechanical parameter selection of the rock; and through the three dimensional elastic-plastic simulation of tunnels anchorage and surrounding rock interaction system, deformation mechanism, failure mode and the safety factor of the surrounding rock have been studied. Research shows that deformation of the tunnel anchorage and plastic zone of the surrounding rock increase obviously with the increase of load. 7 P (P is the design load) is the cut-off point of displacement-load curve and plastic zone size-load curve. It is critical load of the tunnel anchorage, that is to say, the overload safety factor of the tunnel anchorage is 7. Under the condition of overload, the instability failure of anchorage system starts from the shear failure of excavation damage zone, and then the anchorage’s base slab excavation damage zone acts as the bottom sliding surface, plastic zone runs along the anchorage roof arch and sidewall rock through the earth surface. Results of this study can provide theoretical basis for the construction of tunnel anchorage.