Improvement of hydro mechanical behavior knowledge of rock joint from laboratory tests and in-situ experiments

A wide study of the medium (roughly 20 m by 20 m by 20 m) sized superficial sandstone bedrock reservoir, namely Coaraze natural site, France, is planned. Laboratory and site experiments will be compared and the data set will be used for simulations with 3DEC/3Flow ITASCA code implemented with later models. A part of the laboratory experiments is presented here. The BCR3D (3D direct shear box) with its hydraulic sectorized device, and its portable laser beam from 3S (Soil, Structure, Solide) Laboratory, France, is used. The interpretation of the rock matrix characterization tests, of the cyclic mechanical compression test, and the cyclic hydro mechanical compression tests show that the normal stiffness is stress dependent, the initial normal stiffness value, kn0 = 122MPa/mm, dependent on the initial fitting of the two joint walls, and the maximum normal stiffness value, knimax = 164.3 MPa/m, is reached at Smax = 0.5 mm of normal displacement.