In order to investigate the effects of material porosity on mode Ⅰ fracture toughness (KIC),lacustrine silty clay was selected as the research object,and a semi-circular bend specimen with controllable porosity was prepared by consolidation test. The KIC values under different porosity were obtained through three-point bending test. Test results show that a smaller porosity leads to a greater peak load,and the crack propagates along the center line more closely with a better fracture uniformity. With the increase of porosity,the fracture toughness decreases obviously with a rapidly increasing rate of descent. The digital speckle image was used to analyze the whole process of crack initiation and propagation of the prefabricated cracks in specimens. The length of the fracture pro-cess zone was determined from the horizontal and vertical variation characteristics of the displacement cloud diagram,which con-firmed that the failure occurred in the specimen was tensile crack. The mode Ⅰ fracture toughness decreases with the increase of porosity,and the decrease rate increases when the porosity is greater than 38.3％. Finally,the correlation formula between porosity and fracture toughness was established. The formula can be used to estimate the mode Ⅰ fracture toughness of rock-like materials which depends on porosity.
万方数据
维普
