This work is concerned with the numerical representation of the structural behaviour of fractured rock masses. Numerical models have been developed with two main objectives: to represent a dry, blocky type rock mass to represent a blocky type rock mass coupled with water flow along fractures The possibility of occurrence of particular deformation mechanisms in a fractured medium such as slip, large rotations and separations along fracture walls demands that special formulations should be used in order to properly model them. The computer programs presented in this work are based on an already existing model that considers the blocks composing the rock mass as rigid elements (rigid block model). The numerical technique involved in the rigid block model is known as the dynamic relaxation method and the model is in principle able to represent the deformation mechanisms described above. In the present work, an extension to the rigid block model is presented whereby the deformabi1ity of the blocks is taken into account by means of finite elements (deformable block model). The deformable and rigid block models have been coupled with finite element routines that model flow along fractures. In the last part of the work, the developed codes are applied to specific problems involving a blocky type foundation subjected to surface loads. First of all, a dry foundation is considered. Comparisons between the block model and the so-called equivalent continuum representation suggests that the latter is not able to properly model a fractured rock mass when low values of fracture shear stiffnesses are considered. Subsequently, a coupled blocks-flow situation is analysed for a hypothetical dam foundation system. Comparisons are made between the coupled and uncoupled situations. The differences encountered between both formulations are shown to be dependent on the initial fracture apertures.