5Ghaboussi J R, Barboosa R. Three-dimensional and Dis- crete Element Methods for Granular Materials [J]. Im J Nomeranal Methodes Geomech, 1990,14(7) :451-472.
6Duncan J M. Factors of Safety and Reliability in Geotech- nical Engineering[J]. Journal of Geotechnical and Geoen- virortmental Engineering, 2000,126(4) : 307-316.
7Dawson E M,Roth W H.Drescher A Slope stability analysis by strength reduction[J].Geotechnique,1999,49(6):835-840.
8Griffiths D V,Lane P A.Slope stability analysis by finite elements[J].Geotehnique,1999,49(3):387-403.