#LE ROCK DES BLOCS SERIES#

Le comportement géomécanique de la roche fracturée en 3D en réponse aux contraintes in-situ est. construit en extrayant le motif d’affleurement 2D d’un niveau calcaire qui présente une structure en échelle consistant en un ensemble de joints parallèles contigu à des fractures courtes d’un stade ultérieur. Une étude sur l’influence des tensions polyaxiales (triaxiales véritables) sur la perméabilité d’une couche de roche fracturée en 3D est. groundwater, petroleum) in subsurface and upscaling permeability for large-scale assessments. The results of this study have important implications for understanding the heterogeneous flow of geological fluids (e.g. The role of the overburden stress suggests that the conventional 2D analysis that neglects the effect of the out-of-plane stress (perpendicular to the bedding interface) may provide indicative approximations but not fully capture the polyaxial stress-dependent fracture network behaviour. The shear dilation of pre-existing fractures has dominant effects on flow localisation in the system, while the propagation of new fractures has minor impacts. The fractured layer tends to exhibit stronger flow localisation and higher equivalent permeability as the far-field stress ratio is increased and the stress field is rotated such that fractures are preferentially oriented for shearing.

#LE ROCK DES BLOCS SERIES#

A series of numerical simulations is designed to load the fractured rock using various polyaxial in-situ stresses and the stress-dependent flow properties are further calculated. Geomechanical behaviour of the 3D fractured rock in response to in-situ stresses is modelled by the finite-discrete element method, which can capture the deformation of matrix blocks, variation of stress fields, reactivation of pre-existing rough fractures and propagation of new cracks. The 3D fracture system is constructed by extruding a two-dimensional (2D) outcrop pattern of a limestone bed that exhibits a ladder structure consisting of a 'through-going' joint set abutted by later-stage short fractures. Villaescusa (1991) has developed and compared four different methods to define the in-situ degree of fracturing and calculate the in-situ block size distribution, i.e.A study about the influence of polyaxial (true-triaxial) stresses on the permeability of a three-dimensional (3D) fractured rock layer is presented. The authors' experience suggests that individual joints are not infinite but obey typical joint size distributions and that joint terminations define rock bridges (Villaescusa & Brown 1991). Furthermore, these existing models ignore a fundamental characteristic of rock masses, the existence of intact rock bridges. Extensive calculations are required if a representative volume of rock is to be analyzed. Chords calculated through the blocks estimate their size distribution. In general explicit topological block definitions require that joint sizes be unbounded or infinite and that their intersections define explicit three dimensional blocks. intact block identification (Dinis Da Gama 1977) and global frequency calculations (Kleine 1988). In rock engineering several approaches have been used to estimate representative in-situ block dimensions, e.g. The size distribution, shape and degree of interlock of in-situ rock blocks are usually defined by at least three main discontinuity (joint) sets.Įstimates of representative in-situ block dimensions may be required for stability analyses and for rock fragmentation studies, for example. Geological discontinuities divide rock masses into an assemblies of potential (non-overlapping) blocks each of which is more or less an intact coherent rock unit.

Le rock des blocs