Deformation division for surrounding rock of circular roadway by considering rheology and the intermediate principal stress

With consideration to rheological behavior, surrounding rock mass in roadway is divided into elastic zone, plastic hardening zone, plastic softening zone and plastic flowing zone. And the paper derives the stress, displacement and radius of each area based on the Drucker-Prager criterion by considering the influences of pre-peak strain hardening, post-peak strain softening, dilatancy property and the intermediate principal stress. Then discusses the influences of surrounding rock deforming on the basis of a case study. Study results show that both the intermediate principal stress and surrounding rock's rheology have great impact on plastic zone and displacement and the former has a significant interval effect. It can control roadway deforming and plastic zone extending effictively to enhace the intermediate principal stress in a specific range. In theoretical research and engineering practice, ignoring the influences of surrounding rock's rheological behavior is actually overrating the feature of surrounding rock. It is bad for long-term stability evaluation and supporting quantitative design of surrounding rock. And in consideration of the intermediate principal stress, the Drucker-Prager criterion can ensure the safety of engineering better than the Mohr-Coulumb criterion to some extent. This study can provide some theoretical reference for related theoretical research and engineering design in roadway. © 2017, Editorial Office of Journal of China Coal Society. All right reserved.