Justification of cylindrical entry cut geometry in underground mine gallery

Geometry of a cylindrical entry cut in an underground mine gallery is justified using a stage-wise model of rock mass disintegration by blasting. According to this model, at the first stage, a strong blast-induced compression wave breaks the charge–rock interface (crushes and makes plastic), the explosion cavity is expanded, and the crushing zone changes into the radial fracturing zone. During this time, rock mass experiences basic disintegration, and the cylindrical explosion cavity reaches its ultimate limits. At the second stage, the gaseous explosion products (GEP) transmit accelerated motion to broken rock particles toward free surface. The third stage is fragmentation of rocks under the action of GEP and gravity, and blasted muck pile formation. The model determines the key blast parameters in the solid medium: strength characteristics of rocks under all-round explosive loading; relative limit radius of explosion cavity; radii of zones of fine crushing and radial fracturing; efficient blasting pattern design. Using these parameters, new approach to determination of the cylindrical entry cut geometry is justified. The analytical relations are obtained for designing blast patterns in faces. Based on the rational blasting pattern design, the parameters of production and perimeter blastholes are determined. The new drilling-and-blasting designs applied in underground mines of Kazakhmys Corporation made it possible to reduce explosive consumption by 8–12%, to increase broken rock yield per 1 m of borehole by 8–12%, and to ensure the desired grain size composition and the face advance. The cardinal difference of the new procedure from the known analogs is the use of the limiting explosion cavity radius as blast efficiency criterion in the solid medium, which is the first time in the mining science. This new criterion efficiently correlates the blast efficiency with the physical/mechanical properties of rocks, physicochemical characteristics of explosives, and blasting conditions.

Keywords: underground mine gallery, cylindrical entry cut, entry cut geometry, analytical determination of parameters, automated design.
For citation:

Rakishev B. R., Orynbay A. A., Musakhan A. B., Toleuov K. A. Justification of cylindrical entry cut geometry in underground mine gallery. MIAB. Mining Inf. Anal. Bull. 2021;(12):31-46. [In Russ]. DOI: 10.25018/0236_1493_2021_12_0_31.

Issue number: 12
Year: 2021
Page number: 31-46
ISBN: 0236-1493
UDK: 622.235
DOI: 10.25018/0236_1493_2021_12_0_31
Article receipt date: 10.06.2021
Date of review receipt: 04.10.2021
Date of the editorial board′s decision on the article′s publishing: 10.11.2021
About authors:

B.R. Rakishev1, Academician of NAS of the Republic of Kazakhstan, Dr. Sci. (Eng.), Professor, e-mail: b.rakishev @mail.ru,
A.A. Orynbay1, PhD Student, Senior Lecturer, e-mail: asfa_orin@mail.ru, AUES University, Almaty, Kazakhstan,
A.B. Musakhan1, PhD Student, Junior Researcher, e-mail: a_mussakhan@yahoo.com,
K.A. Toleuov, Chief Specialist for Drilling and Blasting Operations, PA ZhCM LLP «Corporation Kazakhmys», Zhezkazgan, Kazakhstan, e-mail: kasiymhan.toleyov@kazakhmys.kz,
1 Satbayev University, Almaty, Kazakhstan.

For contacts:

B.R. Rakishev, e-mail: b.rakishev@mail.ru.


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