Elastic-plastic analysis of surrounding rock in deep roadway based on four-stage stress-strain model

In order to analyze the extent of the roadway rupture zone,a four-stage stress-strain model of the surrounding rock elastic zone-plastic zone-softening zone-fracture zone of the deep roadway was established based on UST criteria and non-associated flow law,considering the influence of intermediate principal stress and the expansion coefficient. Then the closed analytical solution of stress,displacement and plastic zone radius has been deduced. Combined with engineering cases,the effects of different strength parameters,stress-strain models,dilatancy angles,and residual cohesion on the state changes of surrounding rock were analyzed. The results show that strength parameters have a significant influence on surrounding rock stress,strain,and range of post failure. With the continuous increase of strength parameters of surrounding rock,the peak stress and post-peak failure range of circumferential stress increase to varying degrees,and the stress curve shifts to the left,and the expansion coefficient is positively correlated with the strength parameters and the dilatation angle. With the increase of residual cohesive force of surrounding rock,the range of post failure and surface displacement show the non-linear decrease characteristics with a decrease of rate reducing. Compared with other stress-strain curve models,the displacement in post failure zone shows a variation characteristic with EBM>EPBM>ESM> the suggested model in this paper>EPM. Moreover,with the continuous increase of rock dialtancy in post-peak failure zone,the displacement in surface surrounding rock also increases to varying degrees. The dilation angle in the fracture zone has the most significant influence on it,followed by the dilation angle in the softening zone,and the dilation angle in the plastic zone. The analysis results can provide an important theoretical basis for the stability analysis of surrounding rock and the design of support parameters.