5Chen Zuyu, Wang Xiaogang et al, A three dimensional slope stability method using the upper bound theorem--part Ⅰ:theory and methods, International Journal of Rock Mechanics & Mining Sciences 38(2001) 369 - 378
6Sloan, S.W., Upper bound limit analysis using finite elements and linear programming, International Journal for Numerical and Analytical Methods in Geomechanics, 13:263- 282(1989)
7Chen, W. F., Limit analysis and soil plasticity, Elsevier,Amsterdam, 1975
