Geotechnical description and JGS engineering classification system for rock mass

Abstract

This paper presents the new classification system which identifies and designates rock masses based on their fundamental engineering characteristics. The system encompasses the stepwise procedural classification with three steps and a sub-step. The first-step is to classify rock mass into two types; (1) hard rock mass and/or its weathered or altered rock mass, and (2) soft rock mass that is not lithified enough. The second and third steps are to further classify the rock mass based on their inherent structural and physical parameters such as discontinuities, strength of rock material and others that govern the engineering properties. Most of identification items and description terms for classification parameters are adopted from internationally recognized standard (ISO14689-1), and expressed quantitatively. Since, examples on the applicability of this classification system to the actual rock mass of typical infrastructures showed well that this system is suitable for the engineering classification of rock mass.