Trial excavation for underground caverns at Dinorwig power station

At the start of construction of the nine main caverns for the Dinorwig power station, a heavily instrumented trial opening of one section of the Machine Hall roof was excavated under controlled conditions as part of the overall design of the rock-support measures. Following excavation, incremental reductions in the installed support loads were made to provide data for assessing support pressures. Observations of rock-mass behaviour were compared with the results of theoretical studies. The results of the trial were used to assist in the assessment of the design of the remainder of the caverns; they enabled significant economies to be made by increasing the rate of excavation and by reducing the overall quantity of support required. Lors du commencement des travaux pour construire les neuf cavernes principales pour la centrale electrique de Dinorwig, un agrandissement d'essai, equipe d'une gamme grande d'instruments, d'une section du toit de la Salle des Generateurs comme faisant partie de l'ensemble du pr...