Studies on gravity backfilling method for blind backfilling of abandoned coal mines

Abstract

In this paper a new, simple and low cost gravity backfilling method for stabilization of ground above abandoned underground mines is proposed. Laboratory investigations carried out on this simple gravity hydraulic blind backfilling method to fill up a fully transparent model of a section of a bord and pillar mine, have indicated that deposition of the filling material surrounding the inlet hole occurs in a regular shape with full packing up to the roof. Some empirical relationships on maximum volume of sand throughput and spread of sand around the inlet hole have been developed with a view to help the practicing engineers. In the field trial the spread of sand in different directions has been witnessed using an ROV camera fitted with a sonar imaging system. The shape and nature of deposited sand bed surrounding the feeder hole in field and laboratory studies are alike. The empirical relationships developed under field conditions have also been found to be similar to those of laboratory model.