Loose Gangues Backfill Body’s Acoustic Emissions Rules During Compaction Test:Based on Solid Backfill Mining

In fully mechanized solid backfilling mining(FMSBM),the loose gangues backfill body(LGBB)that filled into the goaf becomes the main body of bearing the overburden load.The deformation resistance of LGBB is critical for controlling overburden movement and surface subsidence.During the process of load bearing,LGBB will experience grain crushing,which has a significant effect on its deformation resistance.Gangues block will be accompanied with obvious acoustic emissions(AE)features in process of slipping,flipping and damaging.Under confined compression test,monitoring the AE parameters of LGBB can reveal the impact mechanism of grain crushing on LGBB deformation.The study is of great significance for obtaining an in-depth understanding of the mechanical properties of LGBB,and providing guidance to the engineering practice of FMSBM.In order to study the rules of acoustic emissions(AE)of graded Loose gangues backfill body(LGBB)in confined compression test,this article introduces the AE systems to conventional confined compression test to monitor AE signals resulted from the friction and fragmentation among LGBB.The test results show that in the process of LGBB compaction,AE parameters are highly correlated with the strain-stress curve.AE events of balanced-sized graded gangues are more inactive than other two graded samples in different compression stages,AE events of large-particle-dominated graded gangues are most active.In the spatial distribution,AE events are the most active on the edges and the middle part of test samples and the phenomenon of grain crushing is the most obvious in these positions.