| Rock burst refers to the dynamic phenomenon of sudden and violent destruction of coal(rock)body around coal mine tunnel or working face due to the instantaneous release of elastic deformation energy.It is often accompanied by the instantaneous displacement,throwing,loud noise and air waves of coal(rock)body,which seriously affects the safe and efficient production of the mine.In this paper,the bursting liability of coal and rock mass in Bishan mine is taken as the research object,and the parameters of bursting liability of coal and rock mass are tested and analyzed by combining theoretical analysis,numerical simulation and laboratory test,and theoretical research is carried out on the calculation method of bending energy index of roof strata in different stages of mining face.The evolution law of surrounding rock stress,displacement and plastic zone under different stress environments was simulated,and the following conclusions were drawn:(1)Based on the production geological conditions of the 21-12090 working face of Bishan Mine,the spatial structure characteristics of the roof blocks in the initial mining stage,the initial pressure stage and the periodic pressure stage of the stoping working face were analyzed,the corresponding mechanical models of fixed beam,simply supported beam and cantilever beam were constructed,and the calculation formula of the bending energy index was deduced.By comparing the bending energy index of roof calculated by different models,it is found that the bending energy calculated by simply supported beam is the largest,and the bending energy calculated by cantilever beam is the smallest.And the shear stress and bending moment of beam energy than have nothing to do with load size,only with the beam of the poisson’s ratio and the thickness of the beam is related to length ratio and poisson’s ratio,the greater the shear force and bending moment accumulation energy ratio is higher,the thickness of the beam,the greater the shear force and bending moment accumulation energy ratio is higher,the thickness of the beam as the main factors influencing the bending energy index.(2)Roadway floor lies in whether the horizontal stress of rock bursts occurred in up to the buckling failure of floor strata minimum axial stress,bottom bearing horizontal stress depends not only on horizontal tectonic stress,also affected by the two vertical stress is at the same time,when the bottom bearing horizontal stress reaches bottom Yan Liang buckling minimum axial stress,The strata beam structure of roadway floor will buckle and break,which will lead to floor impact pressure.FLAC finite element numerical simulation software and C-M plastic failure constitutive model were used to simulate and analyze the stress,displacement and plastic zone of surrounding rock under different stress environments.The results show that the plastic failure zone of surrounding rock expands with the increase of lateral pressure coefficient.The horizontal stress of roadway floor decreases gradually with the increase of elastic modulus of coal seam.The horizontal stress of roadway floor decreases gradually with the increase of roadway size.(3)According to the laboratory test data of the bursting liability parameters of the coal samples sent from Bishan Mine,the calculated average dynamic failure time of the coal samples in Er1 coal seam is 357 ms,the elastic energy index is 1.98,the impact energy index is 2.52,and the uniaxial compressive strength is 5.35 MPa.According to the analysis of the most dangerous state,the bending energy index of er1 coal roof is11.53 k J,and that of er1 coal floor is 8.56 k J,using the mechanical model of simply supported beam.There are 45 figures,20 tables and 65 references. |
PDF Full Text Request