Effect of Lateral Stress on the Mechanical Properties of Rock Fracture and Its Implication on the Stability of Underground Oil Storage Caverns

Abstract

It is of great significance to study the mechanical properties of rock fracture for the stability of rock engineering projects. The mechanical properties, including the normal compression and shear properties of rock fracture, are studied by a series of shear tests considering the effect of lateral stress using the self-developed true triaxial test apparatus. The test results show that the initial normal stiffness and the maximum normal closure value of rock fracture increase with the increase of lateral stress, and the peak shear strength and the peak dilatancy angle increase with the increase of lateral stress, whereas the peak shear displacement decreases with the increase of lateral stress. Considering the effect of lateral stress, the improved normal loading model, peak shear strength model and peak dilatancy angle model of rock fracture are established. Using the equivalent parameters of rock fracture obtained based on the test, the hydro-mechanical coupling analysis considering lateral stress is carried out for an underground water sealed oil storage cavern project. It can be concluded that with the increase of lateral stress, the displacement of surrounding rock decreases, and the surrounding rock tends to be more stable.