Mechanical Characteristics And Mesotesting Investigation Of Heated Marble

Heated fracture rock mass is one of the common and complex rock masses encountered in nuclear waste bury, geothermic exploitation and underground development in big city. The strength and deformation characteristics of the fracture rock mass are critical to the design, construction and operation of the relevant projects.In the field of microscopic rock mechanics study, one of the hottest and most important topics is the proposal of the microscopic damage constitutive model, in which different mesoscopic damage mechanisms under different temperatures can also be figured out, to represent the mesoscopic damage evolution of rock mass structure.In this study, marble from Jinping First Stage hydropower station site will be tested; the evolution mechanism of microcracks in heated fracture rock mass will be investigated. The achievements are as follows:(1) Uniaxial compression tests are conducted to study the mechanical characteristics of heated rock. It is show that, compression strength and elastic ratio of heated rock are lower than that of room-temperature rock, and the threshold temperature of marble is about 100°C, the failure pattern and reason of rock samples are given.(2) Using the scanning electron microscopy(SEM), the fracture mesostucture investigation of heated marble is conducted. The fracture pattern and microcrack type of rock are analyzed in the mesoscopic scale, and the microscopic fracture model have transcrystalline damage, intercrystalline damage and coupled transcrystalline and intercrystalline damage.(3) The data of microcrack parameters in different temperature and cycle times is processed based on statistics theory and the regularities of distribution of microcrack parameters are obtained. The microcrack distribution in engineering rock is reappearance by means of the Monte-Carlo stochastic simulation.(4) The fractal dimension and the evolution characteristics of heated rock is studied by the fractal calculation to the two-dimension microcrack network models. The relationship of fractal dimension and temperature, damage variable, mechanics parameters is proposed and this can be a theory and reference for analysing the microscopic changes of inner medium by means of conventional mechanics method.