Abstract: Daye is an underground mine turned from an open-pit one that adopts caving mining method.The serious air leakage from the surface ground during mining process has led to the difficulty in underground ventilation.It was planned to form a capping layer by backfilling with the fragmented rocks and the discarded tailings so as to control the ground air leakage.Based on the laboratory analogue simulation tests, the porosity of the rock particles of four sizes and the air leakage characteristics of the capping were studied and the relationship between the porosity and the cappping height was found, providing not only a theoretical basis for determining the capping height of Daye Iron Mine but also the reference to other similar mines.

Key words: Capping, Analog simulation experiment, Air leakage characteristic