Joint Sets Classification by 3-Parameters, Case Study: Neyriz Marble Mine (Fars Province, Iran)

Classification of discontinuities and fractures in rock plays an important role in study and problem solving in geosciences fields، especially in Engineering Geology and Rock Mechanics. Nowadays، joints are classified on the basis of two geometrical parameters of dip and dip direction، presented on stereonets. It is clear that the behavior of discontinuities cannot be thoroughly presented by these parameters in solving such related problems، as stability of geotechnical structures like rock slopes and tunnels. The present paper deals with the results of a research within which a new method of joint classification by 3 parameters has developed. This is done in 3D environment software، utilizing Matlab and SPSS softwares as supporting programs. Two employed parameters are conventional dip and dip direction، while the third parameter can be one of other joint characteristics such as infilling، length، aperture and so on. In order to check the validity of the method، it was applied in one of the Neyriz Marble quarries، where rock mass contains well defined and clear joints. In this research، the type of infilling of joints has been taken into account as the third parameter، and the results were compared to the traditional 2-parameters classification. This revealed that one joint system defined on stereonets، in new 3-parameter classification، is distinguished as two separate joint systems regarding their type of infilling، namely، iron oxides and non-filling. Field investigation shows the joint system with no infilling is contributing in instability of rock walls and also occurrence of spalling phenomenon in toes of some benches. Utilizing SPSS software، a regression analysis has been performed for each set of joint data، and it is shown that a better correlation factor exists between the values in the new 3D classification. It also shows that the more non-filling joints extend northward، their dips tends to 90°، and this can be a key in slope stability studies، as well as in mining design and planning.