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Shock and Vibration
Volume 2019, Article ID 1828313, 10 pages
https://doi.org/10.1155/2019/1828313
Research Article

Analysis of the Cavity Formation Mechanism of Wedge Cut Blasting in Hard Rock

1Key Laboratory of Ministry of Education on Safe Mining of Deep Metal Mines, Northeastern University, Shenyang 110819, China
2School of Resources and Civil Engineering, Northeastern University, Shenyang 110819, China
3Guangdong People Blasting Engineering Co. Ltd., Guangzhou 510000, China
4The First Engineering Co. Ltd. of CTCE Group, Hefei 230041, China

Correspondence should be addressed to Xiaowei Gu; nc.ude.uen.liam@iewoaixug

Received 18 December 2018; Revised 12 March 2019; Accepted 9 April 2019; Published 9 May 2019

Academic Editor: Fabio Minghini

Copyright © 2019 Zhongkang Wang et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The basic process of cut blasting is to break rock, throw fragments, and form a cavity. Based on the characteristics of cut blasting and the combined effect of stress waves and detonation gas, the evolution process of wedge cut blasting is divided into two stages, and a theoretical model is proposed to investigate the cavity formation mechanism by theoretical analysis and field tests. In phase one, rock breaking is caused by stress waves. By considering the dynamic strength of the rock, a computational model is built for the rock failure zone derived from the coupled cylindrical charge explosion. In phase two, the driving force of the detonation gas overcomes the total resistance of the surrounding rock mass, accelerates fragments, and then throws fragments to form a cavity. The criterion of cavity formation is established on the basis of the quasi-static loading of the detonation gas. The theoretical model provides an overall interpretation of the cavity formation mechanism, in which stress waves break rock and detonation gas throws fragments. A specific case indicates that the range of the failure zone is approximately 18 times the borehole radius in granite and that the hole-bottom spacing of the wedge cut can be designed as 50 cm; in addition, detonation gas is sufficient to overcome the total resistance, accelerate rock fragments, throw fragments, and form a cavity. Field tests present favourable blasting results, with a high utilization rate of boreholes and uniform fragment sizes. Therefore, the model could provide theoretical support and technical guidance for wedge cut blasting in hard rock.