Abstract
The uniquely soft and fragile nature of tectonic coal makes it difficult to obtain core samples suitable for laboratory experimentation. Preparation of reconstituted tectonic coal (RTC) samples generally adopts the secondary forming method. Reliable coal samples are needed to obtain credible permeability and mechanical parameters that can guide Coalbed Methane (CBM) extraction and improve mining safety. In this study, the compaction mechanism of coal particles is analyzed based on the Kawakita model, and optimal sample preparation conditions are systemically investigated, particularly particle size and particle size distribution, forming pressure, and moisture content. The density and P-wave velocity of coal samples were used to test whether the RTC samples were realistic. Finally, the mechanical properties and deformation characteristics of the RTC samples were determined. The results indicate that RTC samples prepared for laboratory testing of mechanical properties require (1) the original particle size of the tectonic coal to be retained as much as possible; (2) a forming pressure that compacts the sample similar to the original tectonic coal; and (3) an optimum moisture content.
Highlights
As like most coal seams in China, coal seams could have experienced numerous tectonic events, including folding, faulting and slipping over a long geological history [1,2,3]
Tectonic coal exhibits a low-strength, weakly cohesive morphology compared to intact coal, and is prone to coal and gas outburst accidents, causing casualties and economic losses, and the exploitation and utilization rate of coexisting Coalbed Methane (CBM) is low [6,7]
Thi aimed to investigate the compaction mechanism of reconstituted tectonic coal (RTC) and the problems that sh considered in the preparation of coal samples, thereby putting forward a more rea sample preparation method
Summary
As like most coal seams in China, coal seams could have experienced numerous tectonic events, including folding, faulting and slipping over a long geological history [1,2,3]. When considering gas drainage borehole drilling and CBM utilization, the research object is the tectonic coal body rather than coal particles, such that the properties of coal particles are of little use [7]. The compaction and mechanical characteristics of RTC samples made form compressed coal particles are closely related to the material properties and forming conditions. It is necessary to systematically analyze the compaction mechanism of tectonic coal particles and prepare more reliable standard samples to make the testing. Thi aimed to investigate the compaction mechanism of RTC and the problems that sh considered in the preparation of coal samples, thereby putting forward a more rea sample preparation method. FFiigguurree11. .StSrtartiafitciafitcioantiaonndamnodrpmhoolorpgyhoofloingtayctocfoianl taancdt tceoctaolnaicncdoatleacttNonoi.c12c1o6a(1l)awt oNrkoi.n1g2fa1c6e(1) work iinn ZZhhaannggjijciocaol amlinme.ine
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