Principal Investigator Herbert Einstein
Shales (in the widest sense) are the most common near surface rocks. Very often they cause problems in civil engineering due to their relatively low strength, high deformability and tendency to swell. Shales can cause significant problems in drilling, making them of strong interest to the petroleum industry. MIT research has concentrated on three aspects: swelling of shales in tunnels, the problems of evaluating shale due to the effects of taking samples out of the ground ("sample disturbance") and constitutive modeling. Based on an extensive series of triaxial tests using specially designed equipment, new insight was gained that formed the basis for a predictive model that can represent the time-dependent behavior of shales (e.g. cracks in samples may worsen over time). In this project, we will work with an analytical model that can represent the inherent anisotropy of shale under true triaxial conditions. Such models are very important to understanding borehole stability.