PRODUCING JOINT POLYGONS,CUTTING JOINT BLOCKS AND FINDING KEY BLOCKS FOR GENERAL FREE SURFACES

This paper describes a process of cutting blocks from statistically generated finite joint polygons in 3D space.If the ratio of joint length divided by joint spacing is less than 10,the rock mass is likely connected.If this joint length ratio is greater than 10,the rock is likely to be blocky.An algorithm is also presented for finding all removable blocks along any given moving direction.The rock mass boundary can be any excavated and natural free surfaces.The algorithm works for both joint sets and for any joint system where each joint has its own direction.This is an application of polygon cutting code DC of 3D DDA.