Mechanical Properties and Fracture Evolution of Layered Gangue-cemented Backfill

This study prepares two types of layered cement filling specimens composed of different strength materials, including gangue, cement, fly ash, and water, to examine the impact of layered structure on the physical properties of gangue cement filling and fracture evolution law. It conducts the uniaxial compression test on a layered filling body by combining acoustic emission, digital image correlation, and others. In addition, this research uses the PFC2D software to analyze the layered filling body’s fracture evolution pattern and damage mode. The results showed that the specimen’s strength and modulus of elasticity reduce, while the cumulative ringing number rises as the height ratio of the layered filling body and the number of layers increase. When the stress is between 74 and 82% of the peak, the layered filling body enters the plastic damage stage, and the AE ringing number sharply improves, which can be regarded as the precursor of filling body instability damage. The complete filling body’s failure mode is mainly a shear failure, and fractures are generated in the weak layer and layered surface of the layered filling. As the height ratio grows, the specimen’s damage gradually changes from shear to tensile. The damaged area is primarily concentrated in the specimen’s weak middle layer and the lower part. Fracture density inside the specimen increases and concentrates at the layers as the number of layers rises.