Compaction Properties Of Gangue And Its Application In Backfilling Coal Mining

Fully Mechanized Solid Backfilling Coal Mining (FMSBCM) is a new coalmining method well developed in recent years. FMSBCM fills solid waste such asgangue, fly ash, construction damp, etc. densely into goaf, so that the coal whitch isdifficult to mine in conventional methods (e.g. coal under buildings, water bodies andrailways) can be extracted safely and effectively, and the problems caused by coalmining such as geological disasters and environmental pollution, etc. can be reducedor prevented, those advantages make FMSBCM a major research area in Green CoalMining. Compaction properties of backfill materials (e.g. gangue and fly ash, etc.) andstrata movment in backfilling coal mining is an important basis of implementingFMSBCM technology. In this dissertation, methods of theoretical analysis,experimental test, numerical simulation and field measurement are comprehensivelyused to systematically research the meso-scale mechanism, macro-scale laws ingangue compaction and theory of strata movement in FMSBCM, and the innovativeachievements are as follows:(1) Based on the compaction tests of gangue, the fractal breakage of ganguegrains in lateral confined compaction was studied, and fractal diemsions of sizegradation with different lithologies, initial gradations, and stresses were gainded; bytaking consideration of fractal crushing, the relation between grain breakage andmacro deformation was established from the aspect of energy dissipation.(2) Random Gravel Model (RGM), a program to randomly generate geometricmodel of accumulated gravel grains with given size gradation, were developed basedon computational geometry. Crushed gangue samples with irregular shaped grainswere modeled in the Particle Flow Code software PFC3d by importing the randomgeometric models generated by RGM program, and the effective conversion ofmechanical parameters from macro-scale to meso-scale were realized, then thenumerical compaction tests were implemented, and laws of grain breakage,strain-stress relation and lateral pressure coefficient K0with different lithologies wereobtained.(3) The double-parameter Winkler foundation supported plate model of stratamovement in FMSBCM were established based on gangue’s compaction propertiesand characteristics of strata movement in bacfilling coal mining. The analyticalsolutions of deflection, internal bending loads and stress distributions of backfilling coal mining panel’s main roof were calculated, and the condition which maintainoverlaying strata don’t breake and its varation with compaction properties ofbackfilling material was derived.(4) Compaction strain-stress ralations of gaungue were successfully used innumerical simulation of bacfilling coal mining panel’s strata movement of a coal mine,and the overlying strata subsidence, stress distribution, plastic zone distribution andstress within bacfill during the retreaing of the face were simulated, and comparasionof numerical and field measured results proves rationality of the double-parameterWinkler foundation supported plate model of strata movement in FMSBCM.