Based on the upper bound limit analysis

the functional program about the slope stability problem was developed by MATLAB. The stability factor (Ncr) and graph of critical slip surface can be visually shown in the program window. The solutions of stability factor (Ncr) were obtained through the calculation results of nonlinear and sequential quadratic programs (SQP)

combined with the method of exhaustion to avoid sticking at the local optimization. The results demonstrated the effectiveness of the program. The influence on the stability of slope was evaluated by analyzing the factors in terms of the internal frictional angle ?

slope angles ? and ?. The calculation results show that the stability factor (Ncr) is more sensitive to the frictional angles ? and ? than ? . In addition

if the frictional angles ? and ? are close to each other and the values of ? and ? fluctuate in the narrow range

the slope stability is sensitive to the stability factor (Ncr). In other words

when the low values of ? and ? are inputted in the program

the slip surface would cross below the slope toe

while the slip surface would intersect at the slope toe for the case of steep slope.