Study on Damage Model and Damage Evolution Characteristics of Backfill with Prefabricated Fracture under Seepage-Stress Coupling

Table 1

Chemical composition of the main raw materials of backfill specimen.

Major element	Coal gangue (%)	Cement (%)	Fly ash (%)
SiO2	56.1	22.95	52.35
Al2O3	18.6	5.32	32.60
Fe2O3	4.6	3.90	2.51
CaO	2.34	62.58	8.13
MgO	1.31	2.06	0.95
SO3	0.12	2.33	0.51
LOI	10.23	2.58	11.62