Defining a graphical basis for developing roughness model of discontinuity

Summary

Abstract

The paper shows how to create graphic backgrounds from photographs of actual discontinuous surfaces of soft rock mass samples. The need for this activity is based on the necessity of creating numerical models of roughness and their connection with traditional methods of assessing the roughness of discontinuities. This paper takes a part of experimental research of time-dependent deformation of soft rock along discontinuities. Experimental research of time-dependent shear strength along discontinuities involved testing of three samples of soft rock – marl, which were sampled from the mine basin Pljevlja (town in the north of Montenegro). The samples have equal geometric characteristics, regular prismatic shape, with an artificial crack formed on each sample of different roughness of discontinuity surface (smooth, waved and moderately rough). The samples were tested in the laboratory, using the existing equipment with necessary modifications and newly designed equipment to provide for proper conducting of the experiment. As known, behaviour of rock mass primary depends of their discontinuities characteristics. One of the most important characteristic is form and state of discontinuity surface. In this paper is presented the way how to define roughness model that could be useful for making numerical connection between shear strength and roughness of the discontinuity. For mentioned activities, it has been used professional photography techniques that obtained quality photos of each discontinuity surface, software Agisoft for quality loading photos and preparing model of surface and Autocad drawing format that could be used for making numerical equations for determinate connection shear strength and discontinuity roughness.