ABSTRACT:
Keyblock analysis plays an important role in the evaluation of the behaviour of jointed rock. Remote sensing technologies are nowadays frequently used to provide the basis for those analyses. Metric 3D images provide accurate and detailed data on the rock mass structure and topography. This contribution outlines the use of metric 3D images for keyblock analysis. First of all, the generation of a 3D image is discussed using the JointMetriX3D and ShapeMetriX3D systems. The following sections describe the evaluated data and its use for the identification of finite blocks in rock faces, the kinematical analysis of blocks and the calculation of block reaction curves. The importance of the use of data from 3D images is illustrated with two examples, a kinematical analysis of a block and the determination of a reaction curve of a block, subject to a rotational slide.
1 INTRODUCTION
Rock blocks and their behaviour govern decisions on engineering works in hard, jointed rock. Although block theory (Goodman & Shi 1985) is a well-accepted method for block analysis, investigation into the behaviour of blocks is still subject of many publications (Um & Kulatilake 2001, González-Palacio et al. 2005, Malmgren & Nordlund 2006). Block analyses rely on the quality of geological investigation results, the assumed loads and the constitutive relationships as well. This paper outlines a consistent sequence of analysis steps for block analysis starting with the acquisition of discontinuity data and ending with stability analyses. Discontinuities in a rock mass such as joints, foliation or faults form blocks. While the blocks usually consist of competent rock, discontinuities represent zones of weakness. The properties and the behaviour of the discontinuities are therefore critical for the analysis and assessment of block stability. The mapping of outcrops and drill cores is the traditional method for the determination of relevant discontinuity data.
