Influence from geomodelling of a fractured rock mass on the mechanical assessment
Résumé
The paper deals with the geomodelling of a fractured rock mass and subsequent mechanical assessment. It is illustrated by the case study of the Saint Beat Tunnel (French Pyrenees). At first the different geomodels and the way they differ are presented. Some examples using gOcad and RESOBLOK Softwares are proposed, and more precisely several geomodels of the Saint Beat Tunnel located in marble limestone affected by four main joint families are discussed. The influence on mechanical computations is presented through RESOBLOK which allowed to run quick limit equilibrium stability analysis. For Saint Beat tunnel considering low mechanical characteristics, the number of unstable blocks can vary from 0 to 170 depending on the geomodel and the associated unstable volume varied from 0 to 61.8 m3 even though the average unstable volume remained less than 6 m3. This case illustrated the strong influence of fractured rock mass geomodelling on mechanical computations. Similar influence could also be transposed to hydraulic or thermal computations.