Title: Experimental study on the influence of moisture content on soft coal strength characteristics

Authors: Chen Wang; Yuwen Gao; Chenye Guo; Kun Wei

Addresses: School of Mining, Guizhou University, Guiyang 550025, China; Chongqing Energy Investment Group Science and Technology Co., Ltd., Chongqing 400060, China ' School of Mining, Guizhou University, Guiyang 550025, China ' Chongqing Energy Investment Group Science and Technology Co., Ltd., Chongqing 400060, China ' Zaozhuang Energy Bureau, Zaozhuang 277100, China

Abstract: The strength characteristics of soft coal are influenced by moisture content. The 8# seam is pretty soft in panel II 883-1 a top slice fully mechanised mining working face in Luling Mine of Huaibei Mining Group. To obtain the influence of moisture content on strength characteristics, corresponding laboratory tests were carried out. With the increase of moisture content in the range from 1.01% to 6.29%, following conclusions are obtained: 1) uniaxial compressive strength and elastic modulus of coal samples decrease gradually; 2) peak strain and maximum axial strain firstly increase and then reach stable at moisture content 4% and 5% respectively; 3) when shear angles are respectively 45° and 55°, peak shear stress and strain increase continuously; 4) cohesion increase gradually; 5) the internal friction angle increases at first and then decreases; 6) additionally, maximum internal friction angle is obtained when moisture content is 4.23%, as well as comprehensive shear strength. In engineering practice, soft coal shear strength and plastic deformation can be raised by increasing moisture content. In this way, the plastic zone width of coal wall in the working face can be reduced. It has a positive significance to prevent rib spalling.

Keywords: moisture content; strength characteristics; soft coal; uniaxial compression; shear tests with variable angles.

DOI: 10.1504/IJMME.2021.119204

International Journal of Mining and Mineral Engineering, 2021 Vol.12 No.3, pp.163 - 180

Received: 19 Jun 2020
Accepted: 23 May 2021
Published online: 29 Nov 2021 *

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