A study on the bearing effect of pier column backfilling in the goaf of a thin coal seam

The pier column backfilling method in the goaf of a thin coal seam introduced in this paper is the latest backfilling technology in China, which has the combined advantages of high efficiency and low cost. In order to fully verify the load bearing effect of this backfilling method, a comprehensive evaluation model which combined the actual measurement, numerical simulation and physical simulation is implemented in this paper. First, the stress bearing formula and backfilling volume rate of a pier column backfilling body is obtained by theory analysis. Then, through field monitoring, it was concluded that the bearing capacity when the backfilling body reached a stable state was similar to the results of theoretical calculation, and no obvious deformation occurred by observation the roadway deformation with the site. Finally, based on the drilling columnar and lithological parameters of the site, corresponding physical and numerical models were established and used to study the bearing effect of this backfilling method. It could be found that the stresses and displacements data that resulted from the simulation relatively confirmed data obtained from the site. After comprehension of above researches, it is concluded that the pier column backfilling method in a goaf has good bearing effect and a good economic benefit for mining thin coal seams.