Triaxial Compression Test Characteristics And Crack Propagation Mechanism Of Phyllite

The anisotropy of rock has a significant impact on the stability of surrounding rock.The angle between the direction of tunnel axis and the bedding angle of layered rock has a great impact on the deformation and failure mode of surrounding rock and the stress mode of supporting structure after tunnel excavation.Therefore,it is necessary to study the anisotropy of layered rocks.In this paper,the mechanical properties of phyllite are studied by uniaxial and triaxial compression tests and particle flow numerical simulation.The main research work is as followsIn the indoor uniaxial and triaxial compression test,the grating sensor is creatively used to measure the strain of the sample.The experimental results are analyzed.The peak strength of phyllite shows significant anisotropy,and the peak strength increases first and then decreases with the increase of bedding dip angle.The failure surfaces of phyllite are compared,and the failure modes of phyllite with different bedding dip angles are analyzed.In uniaxial compression test,when the dip angle of bedding plane ? The failure mode of phyllite gradually changes from shear failure across the bedding plane to shear slip failure along the bedding plane,?= ninety ° There are two failure modes of phyllite.Under the condition of triaxial compression,there are usually one or more longitudinal fracture surfaces,which is the failure of through shear bedding.Then,the numerical model of phyllite samples was established by particle flow simulation program to simulate the whole failure process of uniaxial and triaxial compression tests.The fracture surface of phyllite in laboratory test is basically consistent with that of particle flow simulation,which can ensure the accuracy of simulation results.According to the simulation results,the whole evolution process of internal cracks in phyllite samples is analyzed,and the fracture mechanism of layered phyllite is revealed.Finally,by analyzing the displacement field of phyllite sample under compression,the movement direction of particle unit and the distribution position of microcracks,the fracture mechanism of phyllite is further revealed from the micro perspective.The displacement field of the specimen is small in the middle and large at both ends.By comparing the displacement direction and size of the particle element under three failure modes,the meso mechanism of different failure modes is revealed.