Influence of arch shaped notch angle, length and opening on the failure mechanism of rock like material and acoustic emission properties: Experimental test and numerical simulation

Abstract

The uniaxial compressive failure mechanism of rock like specimens with arched shaped notches was studied experimentally and numerically considering the effects of cracks’ properties on the mechanical behavior of the rocks. The rock like material specimens were provided in laboratory in form of cubes with dimensions of 150 mm × 150 mm × 50 mm containing one arch shaped notch at the center of the specimen where, the notch diameter was changed as 20 mm, 40 mm, and 60 mm. the notch apperture was also varied as 2 mm. 4 mm and 6 mm. The axisymetric axis of the arched notch made angles changed from 0° to 90° by increasing the 15°. In this research 63 different models of the compression tests were made by the two-dimensional particle flow code (PFC2D). The experimental tests and their numerical simulations performed simultaneously to compare them for the arch shaped notch tests under compression. The results of these analyses revealed that the geometric characteristics of the arch shape notch such as the notch diameter, angle and its opening (aperture) governe the failure process of the models and tests under compressive loading conditions. It is also shown that the failure mechanisms of the arch shaped notches and their fracture modes are associated with the compressive strengths of the testing samples. The changes in notch diameter, notch angle and notch opening may make some significant changes in AE hits during the failure process of the specimens. The AE hits grow rapidly after the loading process and before the peak load. Any stress drop may be detected by changes in AE hits during the test. It is concluded that the fracture pattern and failure of the experimental tests and their corresponding numerical simulations are similar to one another which verify the validity and accuracy of the proposed approaches in this research.