A new slice block force-displacement method for slope stability analysis is established on the basis of current research on slice method. In the traditional slice method, mechanical parameters of the limit equilibrium state are applied to describe behaviors of the sliding surface of slope, which means the sliding plane of each slice block reaches the limit equilibrium stress state, and it is suitable for the residual stress state. An ideal elastic-plastic model and a new constitutive model are employed to characterize mechanical properties of the slip face of slice block. Taking the unbalance thrust method as an example of model application, a new method is proposed for determining critical state slice block. The possible failure types of slope are explored. The methods to determine stress and displacement of slice block are presented during the progressive failure progresses. The corresponding stability coefficients are obtained by traditional strength deduction method, comprehensive sliding-resistance method (CSRM), main thrust method (MTM), comprehensive displacement method (CDM) and surplus displacement method (SDM). It is found that, when mechanical parameters have not been changed, the ideal elastoplastic model is hard to describe the processes of progressive failure of slope, but the newly proposed constitutive model is capable of predicting mechanical behavior of each slice block. The proposed slice block force-displacement method can be used to calculate the stability factors under various loading and displacement conditions, to acquire the thrust force and the movement of sliding surface, and furthermore to forecast the stresses, displacements and stability of slope.
