Abstract: In numerical simulation of uniaxial compression, the loading rate is controlled by the variation range of boundary conditions
and the balance time after each change of boundary conditions. At the same loading rate, different combinations of the two factors will
have a great different on the loading effect. Therefore, exploring the influence mechanism of the above two factors on the numerical
simulation test of rock uniaxial compression can play a positive role in doing the efficient and high-precision numerical simulation test
under various loading rates. Using the MatDEM software, based on the loading area and standard equilibrium iteration which set by the
software automatically, changing the division number Nd and balance rate Rb to alter the loading rates of the uniaxial compression
numerical simulation tests. Through the analysis of the simulation results, the following conclusions can be obtained: (1) After one-step
loading, the more number of equilibrium iterations are, the more sufficient the propagation of the stress wave and kinetic energy
equals 0.8), the kinetic energy will decay sufficiently in each step, and the quasi-static simulation results can be obtained with the
lowest amount of calculation. (2) The smaller the stress increment of single-step loading is (the greater the Nd), the more accurate
numerical simulation results are. (3) When the loading rate is fixed and the amount of calculation is the same, loading schemes with low
single-step stress increment and lower balance iteration times (large Nd and small Rb) after single-step loading should be adopted to
ensure the accuracy of numerical simulation test. This paper provides a reference for quantitative study of rock loading rate and related
numerical simulation.

Key words: Discrete element method, MatDEM, uniaxial compression, loading rate