Fatigue Behavior Of Granite-Laboratory Testing And Engineering Application

It is great important to establish the national petroleum reserve for protecting rapid and sustained economic development, safeguarding national security, stabilizing domestic oil prices, stabilizing the domestic market and ensuring the normal life of the civilization. The advantages of the underground petroleum storage caverns are low occupation of farmland, less investment, less wear and tear, less pollution, low costs of management, security and so on. Taking into account the advantages of the underground petroleum storage caverns, national petroleum reserve for China will adopt this style.In the background of a water sealed underground cavern project, fatigue mechanical behavior of granite was investigated using laboratory testing. A fatigue mechanical model of geometrical was proposed, and the operational performance of the water sealed underground cavern project were assessed using numerical analysis. The main contents of the thesis are as follows:Mechanical parameters of granite including cohesion, angle of internal friction, elastic modulus and Poisson ratio ware obtained in the conventional triaxial compression test. Triaxial cyclic loading tests ware performed to study the fatigue mechanical behavior of granite under cyclic loading. It was identified that the boundary point of granite from shear contraction and dilation zones is a critical point for the fatigue mechanical properties of rocks, which is also the fatigue damage threshold of the granite.Based on the metal kinematic hardening models in ABAQUS, a fatigue mechanical model suitable for Geomaterials was proposed. Compared with the existing model, in the fatigue model the influence of the mean stress on the yielding nature of geomaterials is considered, and it is more suitable for the description fatigue properties of geomaterials.The operational performance of a water sealed underground cavern project was assessed using finite element modeling. In the modeling, a user subroutine was composed, in which the influence of mean stress on the fatigue behavior of geomaterial was taken into consideration. Two representative cases were modeled to investigate the influence of crude oil storage and takeout for25cycles in50years, in which the crude oil was stored and takenout synchronously and asynchronously. The study shows that during the operation of the cavern stability and water seal maintain goodloading during injection and takeout affects the caverns. Synchronous injection or takeout exerts a more significant impact on the caverns than asynchronous ones.