Abstract：Based on available test data and fracture criterion，by using probability fracture mechanics and mathematical statistical method，the distribution feature of fracture toughness， ，on rock-concrete interface is analyzed，and a method of defining the least number of specimens of fracture toughness is provided. Weibull distribution or lognormal distribution is often used to analyze lifetime problem，so the two models are preferentially considered in tis paper. The analysis shows that the fracture toughness is of lognormal distribution with degree of confidence ，relative deviation and the least number of specimens of 13. The study results can be used in the probability fracture analysis and construction quality control of rock-concrete interface.
