| Gypsum breccia has special physical and mechanical property, especially it is sensitive to water which has never been met in engineering field in our country. So it is significant to study its damage evolution and fracture appearance under the condition of different water contents.The stress-strain curves and macroscopic failure shapes of gypsum breccia are obtained through uniaxial cycling loading and unloading tests in different water contents. Then 3D views for fracture appearance and parameters of geometrical properties are achieved through 3D laser scanning tests. Based on the theory of rock damage mechanics, fracture mechanics and probability statistics, experimental results are analyzed and some valuable conclusions are summarized as the following:1. Through uniaxial cycling loading and unloading tests of RMT, real-time strain, elastic module and poisson ratio of gypsum breccia are obtained. The relations of water content and damage variable, critical damage are analyzed.2. The problem of rock isotropy damage is discussed and a damage model is build which is applicable to gypsum breccia on the basis of others achievements. And this model considers the important influence of water content in the process of damage development of gypsum breccia. In addition, double-scalar rock damage model is discussed and validated using the experimental results, which indicates that the model is fit for gypsum breccia.3. Through 3D laser scanning tests of fracture appearance of gypsum breccia, 3D parameters of geometrical properties such as asperity height and slope of rough surface and their change with the increase of water content as well as the fractal dimensions of appearance are analyzed by using GIS technique. The results indicate that water content is a significant factor to influence mechanical property of fracture appearance in gypsum breccia, which provides academic foundation to study rule of fractal dimensions in gypsum breccia. |
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