Abstract:To study the halogen corrosion mechanism of artificially filled pillars in underground mining area and provide technical reference for improving the corrosion resistance of materials, mechanical properties and fine microstructure of materials under different corrosion time conditions were studied. Uniaxial compression test and computer tomography scan test were carried out to obtain the damage law of backfill strength and microstructure, and the microscopic mechanism of halide corrosion was analyzed combined with the microscopic images. The results show that as the corrosion time increases from 0d to 360d, the compressive strength and elastic modulus of the cemented backfill gradually decrease, and the rate of corrosion slows down first and then increases. The meso-crack of the backfill expands gradually with the increase of corrosion time, and the surface crack rate calculated by CT scan images shows an exponential growth trend, indicating that the structural damage degree of the backfill is constantly increasing. Appropriately increasing the mass fraction of filling slurry is beneficial to improve the mechanical properties of materials and reduce the crack rate. The negative linear correlation between the compressive strength and the surface crack rate obtained from the test indicates that it is reasonable and feasible to use CT image to predict the strength reduction law of cemented backfill in the process of halogen corrosion. Through the morphological analysis of microstructure, it is found that the invasion of corrosive halide ions and chemical action reduce the bonding degree of cemented body, which is the fundamental principle leading to the strength weakening of Sanshandao cemented backfill body.