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Effect of Humidity on Tensile Strength of Rocks in Selected Underground Coal Mines in Malawi

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Please use this identifier to cite or link to this item:http://hdl.handle.net/2115/66650

Title: Effect of Humidity on Tensile Strength of Rocks in Selected Underground Coal Mines in Malawi
Authors: Yasidu, U.M. Browse this author
Fujii, Yoshiaki Browse this author →KAKEN DB
Fukuda, Daisuke Browse this author →KAKEN DB
Kodama, Jun-ichi Browse this author →KAKEN DB
Maneya, G. Browse this author
Keywords: Humidity
Tensile strength
Roof falls
Underground coal mines
Malawi
Issue Date: 27-Jun-2017
Publisher: American Rock Mechanics Association
Journal Title: Proceedings of US Rock Mechanics/Geomechanics Symposium 2017 (ARMA 2017)
Start Page: ARMA 17-0217
Abstract: One of the major challenges facing coal mines in Malawi is occurrence of hanging roof falls during the rainy season. Following this, the effect of humidity on the tensile strength of coal bearing rocks, arkose sandstone and fine-grained sandstone from Mchenga underground coal mine, was studied aiming to clarify the mechanism of roof fall in the underground mines and proposing countermeasures against the roof falls. Rock samples from the mine were treated in varying humidity levels. Some specimens were oven dried at 80C and a desiccant was used to attain low humidity. Moderate humidity was obtained using magnesium-nitrate-hexahydrate, high humidity was achieved by pure water and some specimens were vacuum saturated. Subsequently, Brazilian test was carried out to obtain indirect tensile strength along the sedimentary plane. For comparison, Neogene tuffaceous Kimachi sandstone from Japan was also tested, following the same conditions. It was confirmed that indirect tensile strength of the rocks decreased with increase in humidity. The sensitivity of indirect tensile strength to humidity for arkose and fine grained sandstones was 12% or 29% larger than that for Kimachi sandstone. The stronger sensitivity for Mchenga roof rocks would be because the rocks contain illite, whose strength is very sensitive to water, while Kimachi sandstone contains only less sensitive zeolite for clay minerals.
Conference Name: US Rock Mechanics/Geomechanics Symposium
Conference Sequence: 51
Conference Place: San Francisco, California
Rights: Copyright 2017 ARMA, American Rock Mechanics Association This paper was prepared for presentation at the 51st US Rock Mechanics / Geomechanics Symposium held in San Francisco, California, USA, 25-28 June 2017.
Type: proceedings (author version)
URI: http://hdl.handle.net/2115/66650
Appears in Collections:工学院・工学研究院 (Graduate School of Engineering / Faculty of Engineering) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)

Submitter: 藤井 義明

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