Study On Broken Depth Of Damage Floor Based On The Group A Coal In PanBei Mine

Based on the systemic analysis on the research status about the broken depth of stope floor strata and damage theory, taking NO.3 coal seam mining of 11113 working face in Panbei mine as an example, rock stress state law of the floor in the process of mining coal seam have been analyzed, rock stress variation characteristics of No.3 coal seam floor of 11113 working face in the condition of integrate floor and damage floor have been simulated through using FLAC3D software, and stress variation characteristics of 11113 working face No.3 coal seam floor have been gained. Making a system description of the floor rock’s initial macroscopic damage and microscopic damage, then according to the crack initiation criterion of damaged rock and underground pressure theory, calculation formula of broken depth under the state of stope floor rock damage have been derived. According to the related parameters obtained by rock mechanics test, combining with FLAC3D simulation, damage variable are derived as 0.574. Then damage variable is used to derive for the calculation formula of broken depth, the broken depth of No.3 coal seam floor on 11113 working face has been calculated to 16.147m. Similar simulation monitor study on the floor damage development process and its depth has been conducted through utilizing the parallel electrical method, and its result is 16m. The result shows that calculative result based on broken floor depth calculative formulas is consistent with the monitor result, which show that using damage mechanics to study broken floor depth of A group coal of 11113 working face in PanBei mine is a scientific and effective method, and it has popularization value in the condition of group A coal mining in PanXie mine area. The research results have important theoretical value and practical significance for the floor water-inrush prevention.