Influence Study Of Anchorage On Creep Characteristic Of Discontinuous Fractured Rock Mass

Intermittent fractured rock mass is a kind of common structure in engineering,which has the characteristics of discontinuity,inhomogeneity and anisotropy.These characteristics determine the mechanical complexity of intermittent fracture rock mass,especially its rheological properties.Creep is a kind of rheological,and the existence of creep greatly increases the difficulty of long-term stability of engineering.Bolt support technology can not only effectively ensure the progress of the project,but also has a good effect on maintaining the long-term stability of the project.However,the mechanism of anchor support is not clear,and the research on the effect of anchor on the creep behavior of intermittent fracture rock mass is also very few.Therefore,the influence of anchoring on the mechanical properties of intermittent fracture rock mass,especially on creep property,is studied from two aspects of laboratory test and numerical simulation.The main work is the instantaneous uniaxial compression test and uniaxial compression creep test of intermittent fracture specimens,and the effects of fracture inclination angle and anchoring angle on the mechanical properties of intermittent fracture specimens are analyzed.The laboratory test is simulated by FLAC3 D,and the simulation results are compared with the laboratory test results.The main research results of this paper are as follows:(1)Based on the instantaneous test results of uniaxial compression.Adding anchor can obviously improve the strength of intermittent fracture specimens,and the peak strength and elastic modulus increase with the increase of anchoring angle,but the application of anchor rod can not change the trend that the peak strength and elastic modulus of the specimen increase with the increase of fracture inclination angle.The application of anchor rod changes the trend that the initial stress of expansion increases with the increase of fracture inclination angle,and the ultimate compression increases with the increase of fracture inclination angle,and the initial stress of expansion of anchor specimen is larger than that of unanchored specimen.The initial stress of capacity expansion decreases with the increase of anchoring angle,and the specimen with anchoring shows that the specimen has better stretchability,and the failure lasts longer,and the degree of failure is deeper.(2)Based on the results of uniaxial compression creep test.When the specimen appears obvious creep characteristics,the stress threshold is generally 20%instantaneous peak strength,when the creep failure occurs,the stress is generally 90%instantaneous peak strength or 95% instantaneous peak strength.The instantaneous strain decreases with the increase of loading stress level,and the creep strain and creep rate increase with the increase of loading stress level.When the loading stress level is low,the creep strain is smaller than the instantaneous strain,and when the loading stress is high,the creep strain is larger than the instantaneous strain.(3)Based on the laboratory test results,the numerical simulation is carried out by FLAC3 D.The simulation results show that the mechanical characteristics obtained by numerical simulation are basically consistent with the experimental results,and the final failure modes of the specimen simulation are consistent with the failure modes of the laboratory test specimen except for a few working conditions.