Equivalent stiffness tensor

Checking the effect of fictitious Joints on the equivalent stiffness tensor... 

We have evaluated the effect of considering the fictitious joints as real joints on the equivalent stiffness tensor T,ju. We can notice that the terms of the equivalent stiffness tensor terms are smaller if we consider 3DEC fictitious joints are real. For the WP3 case (where high joint stiffness values are considered) the differences remain small. It increased up to 30 % for Kn = 4.34 lO Pa/m. 

Table 3 Equivalent stiffness tensor for formation 1 at 2 m scale...

The equivalent stiffness tensor Tijn has been computed up to 5 m scale. No clear conclusion can be given for the mechanical REV. We have notice... 

In this work we have assumed no relation between the joint stiffness and the stress or with the fracture length. This assumption could be revisited later on. We have also considered an isotropic state of stress. Others stress conditions could be applied and would probably involve other kinds of evolution of the equivalent permeability tensor. 

The equivalent permeability tensor K j has been computed at 2 m scale considering the real length of the joint (we have shown the importance to avoid artificial joint prolongations). The REV could not be estimated due to code limitation reasons. The relation between permeability and stress (considering an isotropic state of stress) has been determined and is highly dependent on the joint stiffness value. 

Abstract A new upscaling method has been developed using 3D numerical tools (RESOBLOK 3DEC). This method has been successfully compared with standard analytical approaches in the case of a simple fracture network. This method has been applied to determine the equivalent permeability, stiffness and Biot tensor of a real fracture rock-mass at different scales. The effects of the fracture network properties and of the state of stress on the result have been investigated. 

A new upscaling method has been proposed by INERIS to determine the equivalent hydro mechanical properties of a fractured rock-mass. This method is based on the 3D numerical simulations of the behaviour of a "sample" of fractured rock-mass submitted to different hydromechanical boundary conditions. The simulations are defined in order to determine the equivalent permeability, stiffness and Biot tensor of a fractured rock-mass. 

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