Abstract:By employing 3D laser scanning system,precise measurements of topography on fracture appearance in gypsum breccia under uniaxial compression are taken from which the fracture surface is visualized by using GIS technique. 3D parameters of the geometrical properties,such as asperity height and slope of rough surface are analyzed. The distribution of geometrical properties and its variation with increase of water content are analyzed according to frequency distribution of the histogram. At last,the fractal characteristics of fracture appearance under different water contents are studied. Therefore,the fracture dimensions of appearance under different loading directions and the variation with the increase of water contents are deduced. The test results show that the distributions of asperity height and slope match the normal distribution approximately,and the average of asperity height increases with the increase of water content linearly while the average of slope decreases with the increase of water content linearly. The fractal dimensions of appearance under different loading directions are correlative with water content;as a result,fractal dimension can be one of the important parameters to describe fracture appearance quantitatively. Based on the testing analysis of laser scanning of fracture appearance in gypsum breccia,there are close connections between fractal dimensions of the geometrical properties of fracture appearance and water content under uniaxial compression. The process and mechanics of fracture appearance under uniaxial compression are given as reliable testing basis to further analyze the process of damage evolution and failure mechanism of gypsum breccia.