Experimental Study on Dynamic Response and Damage Evolution of Coal under Shocks by Multiple High-Pressure Air Blasting

Table 1

Physical properties and functions of test materials.

Classification	Samples	Physical parameter	Function
Aggregate	Sand	With the particle size is less than 6 mm	Control the mechanical properties of simulated coal
Cementitious material	P.O.32.5 Portland cement	With the density of 3.0~3.15 g/cm^3
	Gypsum	With the Mohs hardness of 3~3.5, the density of 2.8~3.0 g/cm^3, and the fineness of 400 mesh
Other materials	Mica	With the particle size of 10~15 mesh, which is a flake thin layer structure	Control the random distribution of cracks in simulated coal
	Perlite	A natural silicate mineral with the particle size of 2~3 mm and a unit weight of 80~200 kg/m^3	Control the formation of weak surface structure in simulated coal
	Foaming agent (NaHCO3)	The white crystalline powder with the density of 2.16 g/cm^3, which is easy to decompose and produce gas in a humid environment	Simulate the gas