As solid wastes are generated during coal mining, waste rocks can be backfilled into goaf so as to reduce geological hazards and environmental damage caused by coal mining; however, under different stress regimes, the sensitivities of factors influencing compression-induced deformation (CID) of waste rocks for backfilling (WRBs) are different. In order to control the compression-induced deformation of waste rocks for backfilling more efficiently, compression characteristics of waste rocks for backfilling under four different stress levels were tested by using a homemade loading test system for granular materials based on an orthogonal experiment. The influences of lithology, particle size distribution (PSD), lateral stress, and number of lateral loading cycles on compression-induced deformation of waste rocks for backfilling and sensitivities ranks of the four factors were analysed. The test results showed that: (1) under an axial stress of less than 10 MPa, lateral stress was considered the main factor influencing compression-induced deformation of waste rocks for backfilling; when the axial stress ranged from 10 to 20 MPa, particle size distribution was the main influencing factor; (2) under four different axial stress levels, the optimal combination of influencing factors is sandstone, a particle size distribution from 0 to 10 mm, 3 MPa lateral stress, and 7 lateral loading cycles; (3) to control the compression-induced deformation of waste rocks for backfilling, it was necessary to optimise the lateral stress under an axial stress of less than 10 MPa; while the axial stress was between 10 and 20 MPa, it was essential to optimise the particle size distribution.
Keywords: Factors influencing compression-induced deformation; Orthogonal experiment; Sensitivity analysis; Waste rocks for backfilling.