Abstract: Among factors which affect the stability of granular mixtures slope, external factors play an inducing role while internal factors dominate, but the natural angle of repose of the slope plays a controlling role. In view of this, granular mixture materials of four different compositions (1＜C_u≤7) were prepared and model test was conducted to simulate the instability of granular mixtures slope caused by heap. Results indicate that 1) the angle of repose increased with the increase of non-uniform degree of particle; 2) with the increase of round degree, the angle of repose also tended to increase, but the growth rate was low when round degree was between 1.14-1.40, and higher when greater than 1.40; 3) along with the increase of m, the angle of repose increased at first and then reduced, and finally gradually stabilized; 4) the angle of repose increased with the increase of c and φ in general, but the change was slow in the initial stage. Finally, formula of estimating the natural angle of repose of granular mixture slope was established by fitting the five factors using linear regression theory, and was verified to be correct.

Key words: granular mixtures slope, multiple linear regression theory, angle of repose, influence factor, estimation formula