Abstract
Water injection in coal seams will lead to the increase of moisture content in coal, which plays an essential role in the physical and mechanical properties of coal. In order to study the influence of moisture content on the mechanical properties of soft media, the forming pressure (20 MPa) and particle size ratio (0-1 mm (50%), 1-2 mm (25%), and 2-3 mm (25%)) during briquette preparation were firstly determined in this paper. Briquettes with different moisture contents (3%, 6%, 9%, 12%, and 15%) were prepared by using self-developed briquettes. Uniaxial and triaxial compression tests were carried out using the RMT-150C rock mechanics test system. The results show that the uniaxial compressive strength and elastic modulus of briquette samples increase first and then decrease with the increase of briquette water, while Poisson’s ratio decreases first and then increases with the increase of briquette water. When the moisture content is around 9%, the maximum uniaxial compressive strength is 0.866 MPa, the maximum elastic modulus is 1.385 GPa, and Poisson’s ratio is at the minimum of 0.259. The compressive strength of briquettes increases with the increase of confining pressure. With the increase of moisture content, the cohesion and internal friction angle of briquettes first increased and then decreased.
Highlights
Coal and gas outbursts, and roof hazards in coal mines seriously threaten the mining of underground coal seams and the lives of workers [1,2,3,4]
Coal seam water injection is a common technical means to effectively ensure the safe production of coal mines
It is necessary to investigate the influence of coal moisture content on the mechanical properties of coal
Summary
Coal and gas outbursts, and roof hazards in coal mines seriously threaten the mining of underground coal seams and the lives of workers [1,2,3,4]. Water injection in coal seams will increase the moisture content of coal, reducing the elastic modulus and uniaxial compressive strength [5,6,7]. Chen et al conducted uniaxial compression acoustic emission experiments on coal and rock assemblages with different moisture contents [18]. Yao et al conducted a uniaxial compression test of coal samples and discussed the influence of moisture content on the strength and deformation characteristics of coal samples [19]. They pointed out that the peak strain increased with the increase of moisture content and the tensile strength decreased with the increase of moisture content. The research content is hoped to provide some basis for further understanding the mechanical properties of coal
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