Creep experiment and nonlinear disturbance creep model of gneiss under dynamic and static loads

The stress state of surrounding rock in deep roadway is within the limit of rock strength limit,and the sur- rounding rock will produce large creep deformation,especially the deep disturbance load is more sensitive to the influ- ence of creep deformation of roadway surrounding rock. In order to study the nonlinear creep behavior and creep dis- turbance effect of deep rock under disturbance load,the self-developed rock triaxial disturbance creep test bench is used to use gneiss rock as rock sample and graded loading method. The uniaxial compression perturbation creep test of rock under static load axial pressure,different disturbance amplitude and different disturbance frequency is obtained, and the influence of disturbance load on rock creep characteristics is obtained. The test results show that the axial compression is the dominant factor of creep deformation of rock. With the increase of axial compression,the creep deforma- tion of rock increases gradually. The creep deformation of rock increases with the increase of disturbance amplitude and disturbance frequency. Under the same axial pressure and action time,the disturbance amplitude is more obvious than the disturbance frequency of creep creep deformation;under the same disturbance condition,with the increase of axial pressure,the impact of rock creep damage is more affected. When the axial pressure is greater than 40 MPa,the creep of rock creep is affected by the disturbance. After each disturbance loading,the rock creep strain has a stepped sudden increase,and the creep curve also appears steep,with the disturbance amplitude. And the increase of the dis- turbance frequency,the larger the mutation value. Based on the analysis of the test results,the nonlinear viscoplastic perturbation creep element and the damage original were introduced,and the composite model of rock nonlinear dis- turbance creep damage was established by series connection with Burger. The improved nonlinear least squares method based on pattern search is used to invert the creep parameters,and the results of the creep equations are fitted with the experimental results and the effect is good.