Abstract: To study the distribution of structural plane within rock mass and implement cavability classification and block prediction of ore body，a new method to draw joint iso-intensity diagram with polar coordinate transformation and dynamic counting circle was utilized to identify the main joint groups and the range of occurrence.Quantile-Quantile diagram was used to determine the distribution of geometric parameters of joint surfaces.Then，maximum likelihood method was utilized to calculate the parameters of probability distribution function.The parameters of structural planes in JinChuan Mine Ⅲ were analyzed.Joint distances of Mine Ⅲ obey index distribution and its mean is 0.2 m.There are 4 main joint group in Mine Ⅲ and all obey normal distribution.

Key words: Block caving, Joint surface, Joint iso-intensity diagram, Distribution