Quantitative study on meso-damage characteristics of siltstone under triaxial compression

Abstract：The triaxial compression tests on siltstone from Datansha of Guangzhou City were done by the RMT-150B multi-function automatic rigid rock servo material testing machine.The loads with five different values of 2,4,6,8,10 MPa were adopted as confining pressures.A great deal of mesostructural images of Datansha siltstone were obtained by means of scanning electron microscopy（SEM）.The mesostructural images of siltstone were processed by regional growing theory based on the image processing technique.The meso-damage information of siltstone microcracks were obtained from SEM images.The mesostructural information of microcracks was analyzed by statistical theory and the distribution regularities of microcrack parameters including angle,length,width,area and number were proposed.It is concluded that the azimuth angle,length and width of Datansha siltstone＇s microcracks under triaxial compression obey the regularity of generalized extreme value distribution of variable parameters.The azimuth of microcracks mainly focuses on the angle of approximate 35°.With the confining pressure increasing,there is only a substantial growth along the length of the microcracks,while no development on the width.The energy dissipation approach of siltstone samples under triaxial compression has two ways which are the growth of the number and length of microcracks.