Research About Post-Peak Deformation Features And Brittleness Index Of Granite

With the rapid development of global economy in recent years, the demand of energy source is more and more large. The mining depth and mining rate are increasing, more and more mines at home and abroad have successively entered into a state of deep resources exploitation, and engineering disasters are also increasing, for example:rock burst, strata pressure behavior, large deformation of surrounding rock of roadways, which take great threats into safe and high-efficient deep mining. This kind of disasters are related to the brittle failure process of rock and the post-peak mechanical properties. This paper uses distributed measurement method which is made up of the strain gauges to measure deformation of the brittle failure process in hard rock through static and dynamic measurement, and get the relevant law of rock local damage evolution and crack propagation. According to the local deformation measurement data, Linghai granite brittleness is evaluated accurately which is based on the post-peak energy balance theory. The main research works are listed as follows:1. This paper select Linghai granite as the research object, and conventional triaxial compression tests of granite are made through Rockman207 hard rock triaxial apparatus. The deformation, strength properties and relative threshold for progressive failure under different confining pressure are analyzed.2. This paper proposes and validates a distributed measurement system which is made up with multiple strain gauges, and local stress-strain information of different parts in different confining pressure is gain. Comparison relationship between local stress-strain information and failure mode is found, and strain distribution in load process is expressed intuitively through 2D/3D surface colormap. Damage calculation is applied to locality of rock, so that the local damage evolution law of rock is gain through the loading process.3. Through using dynamic strain gauge and the distributed measurement system with multiple strain gauges, the rock failure process is dynamically captured. Rock failure information is gain in different confining pressure and different control mode, then the deformation characteristics of the strain gauge are compared with rock crack morphology, so that several common failure mode of crack are obtained. The space-time relationship between deviatoric stress drop and rock crack propagation is obtained from stress drop curve of Linghai granite when the rock failures.4. This paper summarizes the relevant research results about rock brittleness evaluate, and relevant evaluation indexes of brittleness are systematically categorized, then feasibility of indexes are discussed and compared in under triaxial stress condition. Failure process energy balance theory (Boris Tarasov etc.) and the relevant evaluation method is improved to evaluate the brittleness of Linghai granite, then a good result is obtained.