Mechanism of crack arrest by peripheral holes during mine rock roadway excavation under blasting

LI Meng; ZHU Zhe-ming; XIAO Ding-jun; HU Rong; SHI Ze-bin

doi:10.13225/j.cnki.jccs.2016.1226

Abstract：In smooth blasting at rock roadway the peripheral holes to a certain extent can achieve a relatively smooth and complete section,and also may play a role of crack arrest to rock mass' s native and blasting cracks.In order to explore the crack arrest mechanism of peripheral holes,in this paper,aiming at the crack arrest of the different spacing peripheral holes to native cracks propagation during the explosion excavation process some experiments and numerical simulation study were carried out.Experiments with a center hole charge,pre-existing cracks (native cracks) and a simplified two peripheral holes plexiglass round specimens,were conducted to observe the effect of native crack's initiation-propagation-arrest under the action of peripheral holes.AUODYN code was applied in the numerical simulation,the linear equation of state (EOS) was applied to the PMMA material.The strength model was elastic and the major principal stress failure criteria was used to predict material status.Along the crack propagation route,a group of target points were designed in order to record the stress histories of those points.Experimental and numerical simulation show that ① between two peripheral holes the compressive stress occurs perpendicular to the direction of crack propagation,the peripheral holes do have the function of crack arrest;② with different peripheral holes spacing,the compressive stress generated between the holes results in different crack arrest effects;③ the smaller the distance,the larger the compressive stress and the crack are more easily arrested.