Abstract: The No.2 ore body in the western district of Baoshan mine is deep-buried and hard to be mined out, thus, the filling method is adopted by using the backfills of cemented waste rock. In this paper, to ensure the mining safety, the compressive strengths of the backfills with seven different mixture ratios at different solidification durations were measured by using RMT-150B rock mechanics testing machine. In addition, the mechanical parameters for the backfills at the solidification duration of 28 days were used to simulate the mining and filling processes of test stop by using FLAC3D. Based on the simulation results, the backfills of cemented waste rock with type C mixture ratio was used to filling in the test stope, and the stress measurements were conducted for the backfills and surrounding rocks. The results show that the water cement ratio and cement sand ratio are the key factors to control the compressive strength of the backfill, and the compressive strength of the backfill with type C mixture ratio at the solidification duration of 28 days was larger than 2 MPa. Meanwhile, the maximum principal stress and maximum vertial displacement decrease with the increase of backfill strength, while the minimum principal stress is the contrary. The stress measurements of the backfills and surrounding rocks in the test stope are in good agreement with the simulation results, which means that the backfills with type C mixture ratio can be used to effectively control the ground pressure in deep stope mining.

Key words: deep mining, cemented waste rock backfills, mixture ratio, compressive strength, FLAC3D simulation