Abstract
The study of the damage process of rock under external loads is good guidance for geotechnical construction design. The differences in rock damage processes and damage modes under different stress paths are rarely reported. To explore the effects of stress paths on rock damage processes, uniaxial compression experiments under three stress paths were conducted. Numerical simulation is also used to simulate the rock acoustic emission (AE) and fracture process. The results of the study indicate that the maximum acoustic emission events are at the peak of stress, and fractures are mainly formed at this stage. The peak of AE energy occurs before the peak of AE events. The damage pattern and fragmentation size of the rock are related to the way the stresses are loaded. It is noticed that there is appearance of a quiet period of AE events prior to the production of significant cracks. Minor damage to the rock is accompanied by the generation of bright white spots in the specimen, which is due to the high tensile or shear stress in the units. When the stress in these units exceeds their strength, the units break down and tiny cracks appear. As the external load increased, the cracks developed and penetrated, and the specimen was damaged. Under cyclic loading and unloading, the number of AE events increased significantly compared with the controlled displacement and controlled stress loading methods, and the radius of the AE circle became larger and the energy also increased, which indicates a greater degree of destruction of the rock under cyclic loading and unloading. The results of the study are of reference significance for rock crack propagation and fracture mode influenced by stress conditions and provide some guidance for construction design under different working conditions.
Highlights
Destabilization damage to rock plays an important role in the field of engineering geology, such as underground mining, petroleum engineering, and slope engineering
After entering the elastic stage, the acoustic emission (AE) events of the sandstone remained at a stable level, and the AE events were basically 0, indicating that there was no substantial damage to the rock at this stage
Peak AE energy is earlier than peak AE events
Summary
Destabilization damage to rock plays an important role in the field of engineering geology, such as underground mining, petroleum engineering, and slope engineering. The cracks produced during rock fracture have a great influence on the permeability of the rock, causing a fluid flow in underground rock, especially for fluid flow in oil and gas reservoirs. Understanding the rock damage process and its damage mode is very informative for geotechnical and oil and gas extraction engineering. Deformation and damage will occur when the rock is subjected to external loads, which is a process of the rock from the development of tiny damage in the intact medium to the formation of macroscopic cracks and eventually leading to global fracture. Xu et al [3] conducted a series of uniaxial compression tests and cyclic loading tests on sandstone samples and the results showed that the ratio of maximum stress and stress amplitude to uniaxial compressive strength is the most important factor affecting the fatigue life of sandstone
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
