Study On Model Test Of The Process Of The Rocklike Materials Failure Based On Acoustic Emission And Image Processing Technology

Due to the complicated geological structure and occurrence conditions, rock is a typically discontinuous medium that always contains a large number of inner defects such as mineral joints, micro-fissures, spaces of particle and so on. Many scholars at home or abroad, have made some research and found that, under loading, some fissures would stretch propagation and coalescence leading to instability and even failure of the rock. Hence, there is great significance for practical engineering that conduct the similar model tests of specimens containing pre-existing fissures. Scholars have made a lot of shudies on specimens containing two pre-existing fissures. But, they have not taken space arrangement factors of fissures into comprehensive consideration for the failure of specimens. In order to study the impacts of space arrangement factors of fissures on the initiational mode、failure mode、mechanical property、acoustic emission characteristics and surface displacement change of specimens,the following work has been done and the corresponding results have been made based on the acoustic emission and image processing technology.①Describing the order of micro-cracks appeared on the tip of pre-existing cracks. The types of newborn cracks are summarized as wing crack, secondary coplanar crack and secondary inclined crack.Considering the impacts of the space arrangement factors of cracks on the initiational mode and failure mode,as follows:With the increase of the crack angle, the failure mode of specimens change from the shear failure to the tension failure when the crack spacing is small,but the failure mode change among the modes of the tension failure when the crack spacing is large;With the increase of the crack spacing, the failure mode of specimens change from the shear failure to the tension failure;With the change of the crack disconnect rate, the failure mode of specimens change among the modes of the tension failure.②Through analyzing the stress-strain curves of specimens under different spacing arrangement,considering the impacts of the space arrangement factors of cracks on the mechanical property of specimens,as follows:With the increase of the crack angle, the initiational stress of specimens decrease and then increase or increase constantly, the peak stress of specimens increase and then decrease or increase constantly;With the increase of the crack spacing, the initiational stress and peak stress of specimens decrease and then increase;With the decrease of the crack disconnect rate, the initiational stress and peak stress of specimens decrease and then increase.③In according to the acoustic emission data and stress-strain data collected in the experiment, analyzing the characteristics of acoustic emission in the failure process of specimens.Get the following conclusion: The level of acoustic emission events under the shear failure mode is low, and the change tendency is same to the stress-strain curve; The level of acoustic emission events under the tension failure mode is high, and the change tendency is different to the stress-strain curve.④In according to observe the displacement vector diagram of specimens and the results of numerical simulation,analyzing the displacement changes of the crack initiation and the specimen failure. Get the following conclusion: When the crack initiation, the deformation of specimens is compression deformation in general, and the specimens have a tendency to move to the bottom; When the specimens fracture, the displacement changes of specimens is large, and the specimens have obvious relatinve slip; The specimens slip along the principal diagonal or counter-diagonal.