CHARACTERISATION OF FRACTURE GEOMETRY USING SPECIFIC CAPACITIES: NUMERICAL AND EXPERIMENTAL STUDY OF A FRACTURE REPLICA

Abstract

In view of the difficulties in determining the void geometry of a fracture by direct measurements, the present study was undertaken to better understand rock characterisation as related to tunnel sealing by grouting, where data must be obtained and utilised in a short time. A fracture replica (295×445 mm-2as constructed and hydraulic tests were performed to evaluate whether the specific capacity (Q/dh) is a robust parameter for estimating the geometry of a fracture. Modelling facilitated the design of the experimental equipment. The study shows that the variations in geometry within the replica were well identified using the specific capacity. Furthermore, the median specific capacity both from the experimental study and from modelling was found to be a fairly good estimation of the effective transmissivity. This was also valid for the hydraulic aperture.