Study Of The Stain And Displacement Law Of Backfilling Of Floor

Starting with the filling mechanism, this paper summarizes the mechanical properties, load-bearing role of backfill and its affection to surrounding rocks, and based on the above, it reveals the functions of backfill mining to floor water burst prevention using numerical simulation software FLAC^3D to contrast and analyze floor stress and displacement variation between backfill mining and caving mining. On the one hand, stress absorption and transfer of backfill bear the upper rock load together. In this way, it improves the stress distribution and status of floor surrounding rock body, increases bearing capacity of floor itself and maintains floor stability jointly. On the other hand, backfill puts stress to the floor of crushing floor heave and then makes it compact for restricting deformation and displacement to maintain floor stability. Through theoretical study of rock mechanics, consideration of mechanical properties of backfill and some simplification, a mechanical model is abstracted to express the work characteristics of the mutual influences between backfill and surrounding rock. From the method of mathematical derivation and the description of the function relation between backfill and surrounding rock, the floor abutment pressure range in backfill mining is obtained. With or without the consideration of periodic weighting, respective analysis of coal seam floor's failure depth is made, and the theoretical formulas are studied. With different simulation schemes, corresponding analysis of how lagging distance and suspending roof height affect the failure depth of floor's plastic zone are made, and a conclusion that backfill suspending roof height and lagging distance are bad for the control of floor's plastic failure zone is obtained. In the progress of backfill mining, temporary support should be strengthened, and the stability of roof and floor should be maintained before and during the backfilling procedure till the backfill can work effectively.The content of this subject is to research floor stress and its failure law of backfill mining. With means of theoretical analysis and numerical simulation, the paper summarizes the floor failure law in backfill mining, and provides theoretical guidance for the next filling operation, floor water burst prevention and safe production of mining.