With 3D nonlinear finite difference method

the influences of deformation

stress

corrosive rock masses and loose strips on dam safety are researched. The result indicates the surface safety degree of bedding is low due to the great water pressure and the bedrock loose effect; the tension plastic zone of dam heel rock masses is closed to the impervious certain

which must be regarded and such measurement is necessary. Elastic and elastoplastic model are adopted respectively on dam material in the overload analysis; Xiaowan arch dam’s safety degree caused by upstream overloading water pressure is 6.5 and 3.5 respectively. So the global safety degree is 3.5 and controlled by the dam strength. Through the distribution and spread process of plastic zone

the rock masses between the elevations 1 160 m and 1 190 m are in transfixing plastic due to the existing of deepl valley and corrosive when the overload coefficient reached 5.0.