The breaking of natural or synthetic dams often causes significant disasters, and the related research is in high demand. Estimation of the dam-break flood is of prime importance in such research,especially when dam safety emergency responses are concerned. In most of the existing dam breach analytical methods, the lateral enlargement of the channel is modeled using slope stability analysis methods. In these methods, the planar wedge failure mode is used in which the slip surface is assumed to be a straight line (Singh and Scarlatos, 1988; Osman and Thorne, 1988; Fread, 1988; Peviani, 1999; Mohamed et al., 2002; Zhu et al., 2006; D’Eliso, 2007; Huang, 2008; Morris et al., 2009b; Wang et al., 2008; Wu, 2013; Chang and Zhang, 2010; Viero et al., 2013; Peng et al., 2014; Dou et al., 2014). However, the geotechnical profession has widely accepted more rigorous analytical methods with circular slip surfaces, such as Bishop’s simplified method (1955) and the method proposed by the U.S. Army Corps of Engineers (1970). The procedure for calculating the factor of safety F is repeated among a variety of possible slip surfaces until a critical one associated with the minimum factor of safety Fm is found. This can be achieved by use of the grid methods, then followed by a procedure to find the critical depth of toe-cutting that makes Fm =1. The calculations can be performed by a computer program DBS-IWHR2015.（download...）