WITHDRAWN: Fracture evolution of fiber-reinforced backfill based on acoustic emission fractal dimension and b-value

Abstract

To investigate the fracture evolution process of fiber-reinforced backfill, uniaxial compression tests were conducted on different fiber types of reinforced backfills. The fracture evolution law of the fiber-reinforced backfill is explored by analyzing the trend of acoustic emission (AE) fractal dimension and b -value with time during the fracture of the backfill. The results show that both amplitude time series values and RA (rise time/maximum amplitude) time series values have good fractal characteristics, but the amplitude time series values have better fractal characteristics compared to RA time series values. In the whole stress change process, the value of the RA correlation dimension ( D ) is relatively small, but at the occurrence of a major event, the reduction and fluctuation of the RA D is larger than the amplitude D . Compared with the fiber-free backfill, the fiber-reinforced backfill has a more pronounced symmetry in the amplitude D and RA D curves and a denser distribution after the peak, and its AE b -value is smaller. At the initial compression stage, there are more small-scale cracks and the D values are large and densely distributed; at approximately 75% or 90% of the peak stress, the D values drop; at the residual deformation stage, the D values rise and fall steeply. The results of the study provide a theoretical basis for the stability control of fiber filling in mines.