Abstract:Based on the principle of the composite element method(CEM),the composite element model of seepage-normal stress coupling for rock fractures is built firstly,with the preprocessor being simple and convenient and containing one or more sets of fractures with specified orientations. The CEM model can further take into account the exchange of the flow rate between fracture and the adjacent rock masses. Secondly,the seepage-normal stress coupling analysis for rock fractures is realized by applying the iterative algorithm between the two fields. The rock fractures are assumed as a filled medium in the model,which enables to treat the rock fractures with or without fillings in a unified way. The relationship between the aperture and the normal effective stress is deduced. The coupling mechanism can be described as follows:in one hand,the normal stress leads to the change of the aperture,which further leads to the change of the conductivity of the rock fracture;on the other hand,the change of the conductivity of the rock fracture brings change of seepage field causing changes of the stress field correspondingly. The numerical example indicates that the normal stress results in the non-uniform hydraulic behavior of fractured rock masses:the hydraulic gradient,the uplift,as well as the seepage speed in local area where the normal stress acts on increase remarkably. Therefore,the importance of the seepage-normal stress coupling analysis in fractured rock masses is emphasized.