The mechanism of permeation and hydrochemical action resulting in failure of loaded rock mass has heen analysed by hydrogeochemical and catastrophic theory

as well as the method of pseudotraction. The criteria that can predict the orientation of the fracture of the macro failure under permeation were derived. lt is found that the permeation may aggravate the interaction and coalescence between cracks in rocks under the compression and may change the orientation on the fracture. The rock strength can be lowdered by the hydrochemical action and the tensile stress of the propagation of cracks will be increased owing to clay minerals. The condition of the fracture in rocks will be satisfied more easily as a result of the synthetic of permeation and hydrochemical action. In view of the above mentioned

some problems of slope instability are discussed.