Association analysis of expansion crack development characteristics and uniaxial compressive strength property of sulphide-containing backfill

The cemented backfill body with sulphide-containing tailings exhibits a swelling phenomenon with an extension of curing age. The test results from the uniaxial compressive strength test of the backfill specimen with an obvious fracture are very discrete, and the mechanical parameters of the filling body will not be obtained effectively. The fractured surface image of the backfill were binarized by the digital image processing technology. Additionally, its fractal dimension was calculated and analyzed. Then, the relationship between fractal dimension and uniaxial compressive strength was established. The results indicate that the cracks on the surface of the backfill specimen exhibite self-similarity. The fractal dimension increases with the development of surface cracks. There is a negative correlation between fractal dimension and uniaxial compressive strength for the sulphide-containing backfill. It is of practical significance to determine the research value of the compression test using the fractal dimension. When the fractal dimension of the surface cracks is less than a certain threshold, the results of the specimen strength tests would be reliable.