Comparative analysis of different strength criteria for deep-buried rock roadway under seepage

The selection of strength criterion will directly affect the stability evaluation and control of surrounding rock. In order to study the effect of strength criterion on the surrounding rock stability of deep-buried circular roadway con- sidering seepage,under the plane strain condition,a unified yield equation was firstly summarized for four commonly used strength criteria of rock materials,such as Mohr-Coulomb (MC) criterion,Drucker-Prager ( DP) criterion,Uniform strength Theory and Mogi-Coulomb (MO) criterion. Then,an ideal elastic-plastic model was established for the deep-buried circular roadway under the action of pore water pressure. With the considerations of seepage body force, intermediate principal stress effect,dilatancy and different elastic strains in the plastic zone,the unified analytical solu- tions of stress field,displacement field and radius of plastic zone of surrounding rock under seepage were deduced based on the elastic-plastic theory. Finally,some comparative analyses were conducted on the various influence factors of the new solutions by a specific example. It was found that the new solutions proposed not only have the form of con- ciseness,but also can flexibly match various commonly used rock strength criteria. The results of MC criterion and DP criteria without considering the effect of intermediate principal stress are relatively conservative. When considering the effect of intermediate principal stress,the circumcircle DP criterion and the uniform strength theory with a weight coef- ficient of 0. 5 can be prioritized,and the unified strength theory with a weight coefficient of 1 should be chosen careful- ly. Intermediate principal stress has interval effect on surrounding rock strength. The strength criteria without consider- ing the effect of intermediate principal stress are generally conservative. The dilatancy of geomaterial is not only related to the dilatancy angle of surrounding rock,but also related to the plastic potential function. The dilatancy does not change the radius of plastic zone,but it will affect the displacement distribution of plastic zone. The actual deformation of surrounding rock will be underestimated without the consideration of dilatancy. The effect of the stress redistribution in the plastic zone should be considered,and the generalized Hook’s law should be used for the analysis,instead of re- garding the elastic strain in the plastic zone as a constant.