Journal of Minerals and Materials Characterization and Engineering, 2021, 9, 499-511 https://www.scirp.org/journal/jmmce ISSN Online: 2327-4085 ISSN Print: 2327-4077 DOI: 10.4236/jmmce.2021.95033 Sep. 9, 2021 499 J. Minerals and Materials Characterization and Engineering Analysis of Roof Failure at the Intersections on a Coal Mining Andre C. Zingano, Marcelo Andrade Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil Abstract The objective of this paper is to understand the behavior of the roof and the cause of roof failure of a coal mining. Eleven roof falls occurred in the mine section in sequence. All the roof falls were surveyed, and the geological fea- tures were determined which include rock type, mechanical properties, and thickness. The immediate roof thickness was interpolated to determine the cause of the roof failures which was the inappropriate roof support where the immediate roof is thicker. The average thickness of the immediate roof was determined by the drilling log in 1.2 m (3.9 ft.). The roof support was design based on the average thickness, and the bolt length is 1.5 m (4.9 ft.) in sus- pension. The challenge was to estimate where the immediate roof gets thicker and to design the support considered to maintain the regular bolt length. This is because the cost and productivity of support operation could increase if the bolt length changes as the roof thickness changes. The idea was to adjust the support for beam building with a fully grouted bolt and rearrange the bolt geo- metry to keep the roof stable. It means, with the same bolt length the type of roof support would change from suspension to beam building depending on when the roof gets thicker. Two empirical approaches were considered to de- sign the roof support: 1) CMRR and 2) RMR. The entry width is 5 m and the roof support was designed with four bolts per row. Where the roof support must change to beam building, the number of bolts per row changes to five or six. The results of the design and application on underground showed that the approach keeps stable. Keywords Roof Failure, Coal Mining 1. Introduction Most coal mines in the southern states of Brazil are room-and-pillar underground How to cite this paper: Zingano, A.C. and Andrade, M. (2021) Analysis of Roof Fail- ure at the Intersections on a Coal Mining. Journal of Minerals and Materials Charac- terization and Engineering, 9, 499-511. https://doi.org/10.4236/jmmce.2021.95033 Received: July 28, 2021 Accepted: September 6, 2021 Published: September 9, 2021 Copyright © 2021 by author(s) and Scientific Research Publishing Inc. This work is licensed under the Creative Commons Attribution International License (CC BY 4.0). http://creativecommons.org/licenses/by/4.0/ Open Access