Experiment And Particle Flow Simulation On Mechanical Properties Of Marble Specimen Containing Oval Holes

After long-term geological tectonization,the rock mass contains multi-scale and multi-shape geological structures such as fissures and holes which have a marked impact on the rock mechanical properties.According to theoretical analysis and engineering practice,stress concentration exits obviously around the hole and it will lead to crack initiation,propagation,coalescence and ultimate failure of the rock specimen.Therefore,it is valuable and meaningful to conduct research on the strength,deformation and the cracking behavior of the rock specimen containing holes.In this research,marble specimens containing elliptical holes are chosen and a series of systematic researches combining uniaxial compression tests and particle flow simulation are carried out.A detailed description can be drawn as follows.(1)A bunch of marble specimens containing one or two oval holes are designed and machined by high pressure water jet.Then uniaxial compression tests are performed by rock servo-controlled testing system with acoustic emission technique and digital photography technology.On the basis of experimental results,the strength,deformation characteristics and crack propagation of marble specimens containing elliptical holes were detailed analyzed.(2)Based on mesoscopic fracturing mechanism,a contact model reflecting progressive damage processes is proposed and discrete element model of intact marble specimen is built.Through ‘trial and error' method and parameter sensitivity analysis,a set of meso-parameters are calibrated in Particle Flow Code(PFC).(3)Numerical simulation of uniaxial compression tests on marble specimen containing oval holes is carried out.The laboratory experimental results on hole-defect marble specimens are verified by PFC modeling.Finally,the distribution of stress field and displacement field is analyzed in order to reveal the meso-mechanism of crack propagation and coalescence.