| The direct roof of the gentle dip bedded ore stope of Guizhou Kaiyang phosphate mine is weak and easy to fall, so the stability of roof is studied through field investigation and ideal elastic-plastic numerical calculation. The following works have been done:1Obtaining stratigraphic information, crustal stress information and rock physical and mechanical parameters and calculating the rock mass mechanical parameters.2Writing Java programs to structure initial stress document for different ANSYS versions, and putting forward EXCEL simple method for high version; Summaring the simulation process of three dimensional stress field.3Establishing the ANSYS finite element model of gentle dip bedded rock mass; Comparing the stresses, displacements and plastic strains of roofs in different depths, and exploring the failure modes and mechanisms of thick and thin direct roofs.4Evaluating the stability of the direct roof with safety coefficient which is defined by the strength reduction method base on displacement mutation criterion. Establishing ordered sample regression assorts class methods to obtain the precise displacement-reduction coefficient curve’s mutation point; Finding out the safety factor of each key point with different depth and thickness combinations and analyzing the influence of depth, thickness and both. |
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