Applicability of a joint constitutive model: correlation with field observations

Abstract

This paper presents the results of numerical studies that illustrate the performance of a new joint constitutive model developed for the stability analysis of large-scale jointed rock masses. The joint model features the reduction of stiffness and strength due to joint initial opening and scale effect, which has been demonstrated by performing a series of direct shear tests. The study thus focuses on the model’s applicability to field-scale rock joints. The movement of a real rock slope is first investigated numerically where the mechanical behaviour of joints is represented by the Mohr–Coulomb model and the proposed joint model. The slope is appraised to be much less stable by the simulation using the developed joint model, which agrees more with the qualitative observation on the site. The response of jointed rock masses to excavation is also examined by simulating two underground rock structures where the mechanical behaviour of joints obeys the developed model in the numerical modelling. Predictions from numerical simulations are in good agreement with field monitoring data surrounding the caverns. Thus, the new joint constitutive law can be utilised to evaluate the stability of large-scale rock structures with sufficient capability.