期刊名称：Eastern-European Journal of Enterprise Technologies
印刷版ISSN：1729-3774
电子版ISSN：1729-4061
出版年度：2017
卷号：3
期号：1
页码：53-62
DOI：10.15587/1729-4061.2017.101444
语种：English
出版社：PC Technology Center
摘要：In the problems of high-speed impact, penetration, explosion, aerohydroelasticity and other non-stationary processes accompanied by high strain rates, program complexes using an explicit method for solving equations of continuum mechanics are widely used. At present, the most promising method for modeling and calculating such problems is the finite element method.Explosive or mechanical creation of initial cracks in the bottom part of the borehole makes it possible to reduce significantly amount of the load necessary for fracture contributing to a more effective development of the shoulder foot. This leads to a reduction in subdrilling. Presence of the subdrilling increases drilling costs by 20...30 %, worsens crushing of the upper part of the rock body and increases fracturing of the upper part of the next shoulder. However, this method requires additional costs and complicates the process of charging wells. One of the possible ways to simplify this method is to form the borehole bottom with a minimum rounding radius of the zone of interface between the borehole bottom and the wall.It was established that the value of the relative radius of rounding between the bottom and the walls of the borehole significantly affects the character of the crack formation in the lower layers. It is possible to overcome the problem of obtaining rск→0 by creating borehole structures with a shock wave concentrator at the borehole bottom. The conical surface of these devices will ensure making the angle between the borehole bottom and the wall less than 90°.
关键词：borehole;subdrilling;stress concentrator;drilling and blasting operations;finite element method;AUTODYN
