Random gravel model and particle flow based numerical biaxial test of solid backfill materials

Fully mechanized coal mining with backfilling (FMCMB) has become a major solution of “green mining”. The mechanical properties of backfill materials are key factors of ground control in FMCMB face. To study the strength behaviors of the solid backfill materials, we developed a method of generating random gravel model by using computational geometry algorithms, then coded the generating method into a program with MATLAB software, and implemented several numerical biaxial tests under different confining stresses by using a generated random gravel model and the Particle Flow Code PFC2d. Peak deviatoric stress, post-peak softening, initial contraction and dilation and the relations between them and confining stress can be observed. And the initial elastic modulus of the samples, Poisson’s ratio, frictional angle and cohesion can be derived from the numerical biaxial test results. The results indicate a good feasibility study of mechanical properties of the solid backfill materials by random gravel model and particle flow based numerical biaxial test.