A uniaxial compressive dynamic damage model for rockmass considering the crack roughness

The influence mechanism the crack on the dynamic mechanical property of the rockmass is always an important and difficult problem in the field of rock mechanics. However, the establishment of the dynamic damage model for the fractured rockmass is the key to solve this problem, which has attracted much attention. At present, most of the dynamic damage models for the fractured rockmass are aimed at the flat cracks, which cannot take into account the influence of the crack roughness. To address this shortcoming, on basis of the calculation model for the rockmass macroscopic damage variable which can take into account the crack geometry parameter, strength parameter and deformation parameter, a calculation model for the rockmass macroscopic damage variable is proposed by introducing the JRC-JCS shear strength model for the rough crack established by Barton, which can consider the crack roughness. Secondly, the proposed calculation model is introduced into the uniaxial compressive dynamic damage model for the rock mass with the non-persistent crack, which both considers the coupling of the macroscopic and microscopic defects, and then a uniaxial compressive dynamic damage model for the rock mass with the non-persistent crack is established which can consider the crack roughness at the same time. Finally, the effect of crack roughness JRC and crack basic friction angle φb and crack length 2a on rockmass dynamic mechanical property is studied with the parametric sensitivity analysis. Taking the rockmass dynamic climax strength as an example, the calculation example shows that the rockmass dynamic climax strength increases from 26.42MPa to 27.28MPa and 28.37MPa with JRC increasing from 0 to 10 and 20 respectively. The rockmass dynamic climax strength increases from 26.42MPa to 27.28MPa and 28.80MPa with φb increasing from 0º to 15º and 30º respectively. The rockmass dynamic climax strength decreases from 31.37MPa to 27.28MPa and 23.90MPa with 2a increasing from 1cm to 2cm and 3cm respectively. At the same time, in order to describe the influence of the crack roughness more accurately, the crack fractal dimension is introduced into the dynamic damage model for the rock mass, which not only improves the calculation accuracy of the model, but also broadens its application range, which is more convenient for practical engineering application.