Numerical Simulation on Pillar Design for Longwall Mining under Weak Immediate Roof and Floor Strata in Indonesia

Hiroto Hashikawa, Pisith Mao, Takashi Sasaoka, Akihiro Hamanaka (), Hideki Shimada, Ulaankhuu Batsaikhan and Jiro Oya
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Hiroto Hashikawa: Department of Earth Resources Engineering, Kyushu University, Fukuoka 819-0395, Japan
Pisith Mao: Key Laboratory of Deep Coal Resource Mining (CUMT), Ministry of Education of China, School of Mines, China University of Mining and Technology, Xuzhou 221116, China
Takashi Sasaoka: Department of Earth Resources Engineering, Kyushu University, Fukuoka 819-0395, Japan
Akihiro Hamanaka: Department of Earth Resources Engineering, Kyushu University, Fukuoka 819-0395, Japan
Hideki Shimada: Department of Earth Resources Engineering, Kyushu University, Fukuoka 819-0395, Japan
Ulaankhuu Batsaikhan: Department of Earth Resources Engineering, Kyushu University, Fukuoka 819-0395, Japan
Jiro Oya: Mitsui Matsushima Holdings Co., Ltd., Fukuoka 810-8527, Japan

Sustainability, 2022, vol. 14, issue 24, 1-13

Abstract: In Indonesia, the adoption of the underground coal mining method is discussed to extend coal production. However, the geological conditions in Indonesia are very weak. In particular, the mechanical properties of the immediate roof/floor in shallow depths are weaker than those of coal. Therefore, the control measures to maintain stability around the developing area should be discussed for safe longwall mining operations. This study discusses the design of safety pillar width in longwall mining under weak geological conditions by using FLAC3D. The study reveals that the conventional equations for the determination of the pillar width, i.e., Obert-Duvall, Holland-Gaddy, and Bieniawski equations, can be adopted to maintain the stability of the pillar itself but are not suitable for the stability of the longwall face because of the influence of the extracted neighboring panels. Additionally, the increase of the pillar width can significantly reduce the fracture zone around the longwall face. Also, increasing the setting load of the powered support can slightly improve the stability. In the pillar design, both the pillar strength and the stability of the longwall face under weak geological conditions need to be considered.

Keywords: FLAC3D; longwall face; pillar stability; powered support; weak rock strata (search for similar items in EconPapers)
JEL-codes: O13 Q Q0 Q2 Q3 Q5 Q56 (search for similar items in EconPapers)
Date: 2022
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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