Study On Mechanical Properties And Energy Dissipation Law Of Coal Measures Sandstone Under High Strain Rate

In the process of mining,the surrounding rock is in a complex environment with high strain rate,such as mine lane blasting operation,coal cutting machine,coal cutting operation,etc..The study of rock mechanical properties and energy dissipation law of coal measures under high strain rate is an important theoretical basis for ensuring the stability of surrounding rock,effective control and safety production.This paper takes coal measures sandstone as the object of study,with the aid of split Hopkinson pressure bar(SHPB)test system,systematically study the mechanical characteristics and size effect of coal measures sandstone under high strain rate,and systematically analyze the energy dissipation characteristics during sandstone failure.The main research results are as follows:(1)Conduct uniaxial compression mechanical properties test of coal measures sandstone under impact loading,stress-strain curves of sandstone with different strain rates and different aspect ratio are obtaine by using the three wave method,and analyze the basic characteristics of stress-strain curve;Obtain the variation laws of dynamic mechanical parameters with strain rate and size effect,such as dynamic modulus of elasticity,dynamic peak stress and dynamic peak strain.(2)Analyze the macroscopic morphology of sandstone specimens after failure,and qualitatively study the failure modes of sandstone under different strain rates and size effect;screen the fragmentation of sandstone samples after failure,and obtain the change law of fragmentation distribution with strain rate and aspect ratio is;Calculate the fragmentation distribution parameter and fractal dimension of sandstone samples after failure,quantitatively study the strain rate effect and size effect of sandstone failure under impact loading.(3)Based on the principle of energy dissipation,calculate the energy of sandstone in the course of failure under different strain rates and different ratio of length to diameter,includes radiation energy,reflection energy,transmission energy and dissipation energy;study the strain rate and size effect of energy dissipation during sandstone failure,and explain the difference characteristics of sandstone failure.The research results can provide important reference for structural failure rule and engineering stability analysis of coal measures strata under high strain rate environment.