Abstract:In order to study the variation law of the influence of rainfall and slurry drainage on the strength of backfill during the construction of open pit backfill discharge, based on the engineering background of Dagushan open pit in Anshan City, Liaoning Province, two different slurry ratios were immersed in water tests and seven different types of rainfall were applied to obtain the compressive strength and strength reduction law of backfill under different conditions. The results show that when the immersion time is 1h, the compressive strength of backfill decreases most obviously, but the reduction range of compressive strength decreases with the increase of immersion time. Rainfall intensity has a significant effect on the early compressive strength of the backfill body (3d, 7d). The greater the rainfall intensity, the higher the reduction degree of the early compressive strength of the backfill body, and the lower the compressive strength. When the rainfall exceeds 7mm/d for three consecutive days, the discharge construction should be stopped.