Uniaxial Compression Test And Numerical Simulation Of Like-rock Materials With Pre-crack

Rock mass is a structure with internal discontinuities such as faults,joints and beddings.Its complex structure makes its physical properties uneven and anisotropic,making the research work of cracked rock mass difficult.It is of theoretical and guiding significance to study the different mechanical characteristics and fracture mechanism of fractured rock mass in different state of crack.In order to study the failure mechanism of fractured rock under uniaxial compression mechanical characteristics and fracture,and the reality of cement mortar material for rock similar preparation of specimens,the crack of prefabricated by pull out test piece maintenance pre embedded steel plate to form the through crack specimens of different forms,maintenance is completed,with the help of RMT-150 B rock mechanics testing machine of prefabricated crack specimens subjected to uniaxial loading,the loading process using high-definition digital camera shot in real time on the loading process,and photographed the final failure mode.At the same time,the use of particle flow discrete element software PFC2 D to establish the numerical model is close to the experimental results of numerical simulation,combined with the experimental phenomenon in the process of test results and further analysis of mechanical characteristics of fractured rock mass and fracture failure mechanism.The following main conclusions are drawn:(1)the establishment of open crack under uniaxial compression stress model,calculate the change state of stress crack of I type and II type stress intensity factor,and that I type crack crack stress intensity factor decreases gradually with the increase of crack angle,the stress intensity factor with the increase of crack angle and then decreases II type crack crack crack in the open,the dip angle is 45 degrees maximum.Based on the maximum circumferential stress principle and strain energy release rate theory,the I and II composite fracture problems are solved,and the relationshipbetween the crack initiation angle and the initiation stress condition is obtained.(2)the single axial compression peak compressive strength of single through preformed crack increases with the increase of the crack inclination.In uniaxial loading,0 degrees angle crack crack initiation in the central form of prefabricated crack tensile crack was born in adorable,90 degrees angle crack specimen peak was not observed before crack initiation,crack specimens of other angle crack in the wing crack in the form of prefabricated crack initiation.The ultimate failure modes of single fracture specimens are mainly diagonal shear failure.(3)under the same crackle angle,the peak strength of rock like specimen shows the largest single crack specimen,the T type crack is the second and the cross crack is the smallest.T type and cross crack specimens under uniaxial compression failure mode with diagonal shear failure.The crack propagation mode,30 degrees,45 degrees and 60 degrees angle crack specimens are close to the initiation of wing tension crack prefabricated crack tip,and extend along the direction of the force,and with continued loading shear crack initiation,crack tip,shear crack growth rapidly,and the specimen edge lap through,therefore,the peak strength also demonstrated more close.The cross crack specimen with 0 degree and 90 degree inclination is closer to the crack initiation and propagation mode.The difference is that the 90 level inclination specimen has a compaction phenomenon during the loading process,and the peak strength is slightly higher than that of the 0 degree inclination specimen.(4)PFC2D numerical simulation results show that the acoustic emission phenomenon of model specimens is concentrated in the middle and late stage of loading.Especially after the peak strength of model specimens reaches peak value,acoustic emission events accumulate rapidly,and macro cracks appear on the surface of specimens.The tensile stress at the tip of the crack decreases with the increase of the crack inclination angle.The tensile fracture behavior at the crack tip is gradually suppressed with the increase of the crack inclination angle,which is close to the theoretical result.The model crack initiation and failure mode is basically consistent with the laboratory test,and the numerical simulation results are good,and thesimulation is more successful.