The effect of joint constitutive laws on the modelling of an underground excavation and comparison with in situ measurements
Résumé
The paper discusses the results of a numerical study which examines the influence of joint constitutive models on the response of a specific jointed rock mass mane up of an anisotropic rock (slate). It presents a comparison between predicted convergences and displacements of rock mass surrounding a pilot gallery, and those measured during field investigations. To perform this analysis, the two-dimensional Distinct Element Method code, UDEC, is used and three joint laws are compared. Based on field investigations for site characterisation, two models are constructed according to fracture density (MODEL A and MODEL B). For each of them, the influence of joint constitutive law on the stability of the gallery is examined, and comparisons between the investigations and predictions are made. Examination of the results shows that there is no noticeable change in stress magnitudes between laws. The displacement magnitudes depend on (1) the constitutive law, (2) the input model parameters and (3) the fracture density. A parametric study in the case of MODEL A indicates that a relatively good march between predicted and measured displacements around the gallery can be observed in certain areas.