Abstract—In geomechanics, the knowledge and the characterization of the in situ stress state is required for applications encountered in Rock Mechanics; it may be obtained by measuring the strain response of the ground under the effect of a known stress. Actually, several technics have been developed to estimate the in-situ stresses. Among these methods, we are particularly interested in the overcoring test, which consists of measuring displacements and deformations generated to the borehole walled after the relaxation involved in the drilling of a coaxial ring. If the rock model behavior is irreversible, thus, the interpretation of overcoring test becomes delicate. The analysis presented in this document is devoted to the direct problem. The tridimensional modelling is used taking into account the drill progress. In this work, the process used in the overcoring test of elastoplastic isotropic rock is analyzed by a numerical approach, by using a tridimensional modelling via the perfect elastoplastic model of Drucker-Prager without hardening. The strains studied correspond to those given by the cell CSIRO gauges (Worotnicki and al, 1976). The tridimensional study put in evidence the difference in the time for the cases of hydrostatic and deviatoric loading.
Index Terms—Stress, overcoring, tridimensional modelling, numerical simulation, elastoplastic medium.
The authors are with the Laboratory of Environment, Water, Geomechanics and Structures (LEEGO), Algeria.& Faculty of Civil Engineering, University of Science and Technology Houari Boumediene, USTHB, Algiers, Algeria (e-mails: firstname.lastname@example.org, email@example.com).
Cite: Chikhaoui Mohamed and Nechnech Ammar, "Tridimensional Numerical Contribution of Displacements Evolution in a Rock Subjected to a Deviatoric Loading Using Overcoring Test," International Journal of Engineering and Technology vol. 5, no. 1, pp. 109-113, 2013.