Introducing a new method for calculating the blocks volume caused by joints effect in tunnels

Discontinuities within the rock mass can divide the rock into blocks with different sizes and shapes based on the geometrical parameters and pattern of existing joints. The volume of blocks created by cross-cutting of joints has a key role in underground works and selecting the proper supporting system. In this paper the possible shapes which a block can take as a result of the cross-cutting of the joints, as well as the general principles existing in block volume calculation methods are described, and a new method which concerns an especial focus on dip angel, strike, spacing and density of joints is proposed. By this method the block volume calculation is performed more accurately. The software used in this study is AutoCAD. This method proved an acceptable result on a case study performed on a part of horseshoe tunnel of Marvdasht railway having 8 (m) length and 5.35 (m) diameter. This tunnel has been drilled within limestone rock using blasting method. (A) This paper was presented at Safety in the underground space - Proceedings of the ITA-AITES 2006 World Tunnel Congress and the 32nd ITA General Assembly, Seoul, Korea, 22-27 April 2006. For the covering abstract see ITRD E129148. "Reprinted with permission from Elsevier".