This paper describes the influences of soil parameters on bifurcation analysis，using a non-coaxial Camclay model of normally consolidated cohesive soils during undrained shear under plane strain condition. The soil parameters are estmated from plasticity index. The soils exhibited a wide range in plasticity index，from lO−50．
The results indicate that bifurcation behavior using a soil with lower plasticity index occurs at a larger stress ratio and a smaller strain compared to soils with higher plasticity index. It is possible to predict the pattern of slip surfaces from the distribution of maximum shear strain derived from the results of bifurcation analysis．