Study on pore evolution and porous elastoplastic deformation characteristics of anthracite after high temperature

In order to study the pore development characteristics and deformation law of anthracite after pyrolysis, anthracite is pyrolyzed at room temperature -500 ℃, and then uniaxial compression tests are carried out on Ф50 mm×100 mm samples and stress-strain curves are obtained.The characteristics of pore evolution and deformation of anthracite are analyzed by mercury injection experiment.The results show that the development of macropores dominates the whole process of deformation and pore evolution, and the threshold is 300 ℃.Medium and large pores control the destruction mode of anthracite, and the destruction mode changes from brittle failure to ductile failure at 300 ℃.The conventional macroscopic elastic modulus method considers that the coal body is completely elastic deformation, but the experimental results show that the deformation is both elastic and plastic.The higher the porosity is, the more porous plastic compression deformation is.The true elastic modulus is defined and the calculation method is given.The complete elastic deformation and the porous plastic compression deformation are separated.The hardening model of porous plastic deformation is established and verified by numerical calculation with good coincidence.