Abstract:Fractures are important factors that control the stability of rock masses and need to be properly studied as demanded by modern rock engineering. For many decades,scholars at home and abroad have paid much attention to the study of the properties of random fractures,especially the geometrical properties of random fractures. But how to represent the random fractures intuitively that can be easily understood by practicing engineers remains to be a problem. Based on accumulated experiences during recent years with important rock engineering projects,this paper discusses an accurate representation method for random fractures of fractured rock masses. A data set with 2190 fractures investigated from the field of the Three Gorges dam site is used to be a case study,a conventional method of contour map and scatter plot of Schmidt lower hemisphere projection is shown some shortages of representing the distribution and delineation for the data set,because of the poles of fractures are randomly distributed in the Schmidt lower hemisphere projection. A new method to delineate the dominant fracture orientation by probability and statistics method applies the rule of right hand to classify the fracture orientations in order to clarify the geometrical features of fractures with more precision without personal judgments. A computer program is developed to carry out the complicated calculation and the visualized diagrams of fractures orientation by right hand rule are represented in the paper so as to be used by practicing engineers.