The Effect of Acid Mine Drainage Corrosion on the Creep Deformation of Cemented Gangue Backfill

Acid mine drainage (AMD) is a hazardous by-product of coal mining, which may intensify the creep deformation of cemented gangue backfill (CGB) in solid backfill mining. In this study, the long-term stability and creep property of CGB soaked in AMD were quantitatively measured by experimental and theoretical analysis. The uniaxial compressive strength, elastic modulus, and mass of CGB soaked in AMD, with pH of 5.56 and soaking time of 30 to 360 days, were tested. The change trend of compressive strength, elasticity modulus, and mass first increased, then decreased, and finally ended at 94.37%, 96.68%, and 98.00%, respectively. The respective creep processes of CGB soaked in AMD and untreated CGB were similar, initial creep stage lasted only for a short time, and no creep deformation occurred in the steady creep stage. Moreover, the long-term strength of CGB soaked in AMD was 98.6% of the untreated CGB. The creep law of the CGB soaked in AMD was accurately fitted by using the Kelvin model. The theoretical analysis revealed that the final creep deformation of the CGB column soaked in AMD was only 4.4 mm. The results of this paper show the possibility of using CGB in AMD-accumulating goaf.

Engineering design of selecting particle size of gangue under solid backfill mining for protecting water resources

In view of the ecological environment damages caused by the loss of water resources and the gangue accumulation during coal mining, this paper proposed a solid backfill mining method to recover the coal seam under the water body, which could fundamentally reduce the sinking space of the overlying strata, and better prevent water-flowing fractures expanding. Consequently, according to the deformation characteristics of the overlying strata of the solid backfill mining, a mechanical model was established for superimposed beams on elastic foundation with simu?lating the expansion water-flowing fractures under solid backfill mining. A method of calculating the height of the water-flowing fractured zone was provided, and the mechanical mechanism of the development of water-flowing fractures in the overlying strata under solid backfill mining was expressed. Meanwhile, the backfill rate of the experimental working face was designed as 80% to avoid the ecological environment damages caused by gangue accumulation. The stress-strain characteristics of gangue samples under different grading size schemes were further studied.