Prediction of hydro-mechanical responses of a long – term pump test in Sellafield site

Under the auspices of the DECOVALEX II international project, the coupled hydromechanical responses, in the fractured volcanic rocks at Sellafield site, to a pump test and shaft sinking were studied. The aim of this paper is to describe the methodology for analysing the hydromechanical responses of a long-term pump test in borehole RCF3 drilled on the centreline of one of the proposed shafts. This methodology is based on the Discrete Fracture Network (DFN) approach for hydraulic analysis and the discrete approach, where the main discontinuities are explicitly represented in model. The principal advantage of using the DFN approach is to change easily the scale of the study without important modifications of the network. Hydraulic properties of the different types of discontinuities were evaluated by calibration of the flow rates measured in the site.