The sand pile avalanche model simulates the occurrence of avalanches in sand and plots the frequency of these avalanches. With the increase of sand particles, the shape and size of sand pile are easy to model. But even though the shape of the pile is conical, a new grain of sand can also trigger avalanches. Some sand particles fall off the cone. And because these avalanches are unpredictable, it's impossible to predict whether the next grain of sand will lead to avalanches.