Abstract: Due to nonlinearity of ground material’s behavior, the error will be induced using traditional superposition method to calculate bearing capacity. The main cause of superposition error is that the bearing capacity factors based on failure mechanism of weightless soil is not applicable for weight soil. Based on slip line method, variation trends of error induced by superposition method is analyzed; and bearing capacity factors which could reduce the error effectively or eliminate the error completely are calculated. The investigation results show that, bearing capacity calculated by traditional superposition method is conservative; the error increases with increasing of internal friction angle and decreases with increasing of cohesion. Error induced by superposition method will be reduced effectively or eliminated completely if bearing capacity factors considering soil weight.

Key words: bearing capacity, bearing capacity factors, superposition method, slip line method, error analysis