CONSTITUTIVE EQUATION FOR NONLINEAR STRESS-STRAIN CURVES IN ROCKS AND ITS APPLICATION TO STRESS ANALYSIS AROUND A BOREHOLE DURING DRILLING.
Academic Article
Overview
Overview
abstract
The stress-strain behavior of Berea, Ohio, and Pecos sandstone was measured intensively under triaxial loading paths. Both compression and extension tests were performed at different pore fluid pressures. The characteristics of these modes were studied, and a nonlinear model was developed to represent the important characteristics, i. e. , the four modes, of the behavior of sandstones by means of a constitutive equation in such a way as to satisfy certain mathematical requirements. A finite element model using nonlinear stress-strain relationship was developed which simulates the stress state of a structure up to failure. The finite element model was used to predict fracture pressure around a borehole during drilling. The shape of the borehole is either circular or elliptic, and the tectonic stress is directional.
