A Study On The Mechanical Behavior Of Three-dimensional Irregular Ore-rock Particle Fracture

After the mine is exploited,the ore exists in the form of particles.The ore particle crushing conditions are complex,and there are many factors should be considered in analyzing.For explore the influence of irregularity on rocks rupture mechanical response characteristics and failure characteristics,author relies on the National Natural Science Foundation(51774101)and existing researches,using the lab test,numerical simulation and theoretical analysis methods,to explore the mechanical response characteristics and failure mode which are impacted by varying loading rate and shape indexes.Furthermore,author successfully build the three-dimensional irregular sandstone particle model based on digital image processing tech.It's for purpose of demonstrating that what a role is played by the axial coefficient and overall contour coefficient in the model's mechanical response characteristics,rupture mode and acoustic emission characteristics.Besides,author corrected the Dimensional Effect and Shape Effect in Rock Particle Strength Calculation Formula.The main research conclusions are as follows:(1)The different shape on the rock mechanics and rupture characteristics were carried out in different loading rates.The loading rate effect is showed in regular and irregular rock sample.The stress drop down in the lower loading rate condition,peak strength,residual strength,and elastic modulus have a good fit relationship with the loading rate,which is positively correlated.When the sample at a low load rate(0.0005mm/s),its rupture mode is a complicated mode of the compression belt and the high shear mix.When the load rate is greater than 0.0005mm/s,the sample is highly cut down or longitudinally split.destruction mode,the failure form is simpler.And this feature is also reflected in irregular test pieces.(2)Numerical experimental study on the axial coefficient,overall contour coefficient varying on sandstone mechanical properties,rupture characteristics and acoustic emission characteristics.When the axial coefficient of samples increasing,it's peak strength and residual strength are decreased.When the axial coefficient L=3,the two strength have the lowest value.In contrast,the relative regular,smooth sample's failure mode is pulling the mixed destruction mode,and producing more stretching units.The damage strength is positively correlated with the overall contour coefficient,and the linear correlation is strong;the stress concentration of the general contour coefficient increases is more obvious,and the damage mode is turned from the mixed destruction mode,pulling,shear,longitudinal splitting and more mixed damage mode.With reduction in the overall contour coefficients will causes the number of inside of the test piece to increase,and the damage unit is stiffly degraded to generate a large amount of stretching unit.(3)Author pickups the experiment of predecessors,screening the Dimensional Effect parameters in the intensity calculation formula,correct,and obtaining a tablet compression intensity calculation formula that does not rely on the volume of the test piece.Then,author also analyze the Shape Effect index parameters on particle strength,resulting in a particle rock strength empirical formula q_ua=167.5728-55.7460 which depended on single-panel compression test.