Study On Dynamic Mechanical Properties Of Coal Based On SHPS Test

Coal reserves are abundant in Western China,and it is the main producing area of coal production at present.However,due to the coal forming characteristics and production process(including mining,transportation,machine reproduced)effect,to the user when coal is broken,coal powder,block rate is low,seriously restrict the use of coal value.In view of this,people have begun to carry out all aspects of research,in order to increase the percentage of raw coal,the long deep hole blasting in coal seam is one of the effective technical means,and the study of the dynamic mechanical properties of coal is the foundation.Therefore,the coal Yanghuopan coal mine as an example,using laboratory impact test combined with numerical simulation,the mechanical characteristics of the dynamic impact of coal.Using the separate Hopkinson pressure bar(SHPB)experimental equipment,the impact test of coal was carried out by using 50mm taper rod,The dynamic mechanical characteristics of coal under different pressures(0.15MPa,0.20MPa,0.30MPa,0.40MPa and 0.50MPa)are investigated.The tests were carried out without confining pressure and passive confining pressure respectively,speed is 2m/s to 7m/s.Through the collected data,The stress,strain and strain rate are obtained by three wave method;Then the stress,strain and strain rate time history curves and stress-strain curves are obtained by processing and analyzing the data processing software.Experimental results show that:(1)The correlation between strain rate and loading rate is obvious,Obtained by fitting:?= 3.750v2-3.624v?43;With the increase of loading speed,the stress-strain curve of the overall rise curve at the early stage of loading,the elastic stage has a short period of time,after the obvious plastic deformation,and reached the peak,in a very short period of time,the strain stress continues to increase,remain unchanged,and finally into the unloading stage,the strain will appear rebound phenomenon;Under passive confining pressure,the resistance to failure of coal increases,and the stress-strain curve increases,Axial stress increases 1.0?1.3 times than without confining pressure,The strain resilience is obvious,which shows that the sleeve can enhance the anti deformation ability of the coal specimen.The dynamic mechanical properties of coal are simulated by using ANSYS/LS-DYNA,and the results show that the failure of coal begins at both ends and center,and gradually penetrates until it is broken.According to the stress and strain data of numerical simulation,the dynamic stress-strain curve of coal is obtained,The corresponding loading speeds are 3m/s,4m/s,5m/s and 6m/s.By comparison,the variation trend of the stress and strain agrees with the experimental curve,which proves the validity of the experiment.