A New Approach to Rapid 3D Mapping of Rock Mass Structure

Alparslan TURANBOY
Seydisehir Voc. Sch. of High. Educ., Selçuk University, Konya, Turkey
Department of Computer Engineering, Selçuk University, Konya, Turkey

Key Words: Discontinuity, rock mass, mathematical transformation, isometric perspective, 3D mapping.

ABSTRACT: The prediction of rock mass behavior is an important task in many engineering projects, as the behavior of rock masses can be controlled by the presence of discontinuities. Being able to map the structure of a rock mass is crucial to understanding its potential behavior. This understanding can positively impact the safety and efficiency of an engineering project. In this research, rock masses were mapped and analyzed using
linear mathematical transformations and isometric perspective methods to achieve meaningful three-dimensional (3D) results. The rock mass fracture representation is based on explicit mapping of rock faces. The developed model can improve safety and productivity through its application in the determination and analysis of rock mass structure for geological and geotechnical assessment. Based on the methods explained here, a software system was developed for analyzing the geometric characteristics of discontinuities in a rock mass. In this model, discontinuities in a rock mass can be visualized both individually and in combination, and cross-sections can be generated at any desired location. In addition, intersection lines between discontinuities can be generated as dip direction vectors. The natural structure attained by using this developed model agrees well with field measurements.

  • Introduction
Visualization is the task of generating and understanding images that contain important features. Visual sight constitutes 70% of sense of object perception (Ming and Peter, 2006), which is valid in engineering applications, where the structural reconstruction of an actual object is a required step for accurate visualization. To comprehend, render, and reveal complex structural objects such as in open pit mines, appropriate geometric models must be designed. Two-dimensional (2D) models, including geological maps, cross-sections, sketches of strain and stress patterns, and stereographic nets, are used in mining operations. Normally, the set of observations and measurements supporting these models is small in relation to the complexity of the real objects from which they are derived. Therefore, these models need additional guidance and explanations. However, geological modeling techniques have evolved from highly conceptual methods to practical computing methods, which include three-dimensional (3D) approaches (Zhong et al., 2006). 3D models are accepted as promising tools for a better comprehensive understanding of engineering object characteristics. Accurate, detailed 3D representations of real objects are needed for successful engineering design. In addition, suitable representations can prove to be useful as strong communication tools between technical experts and nonspecialists. In designing large and risky engineering structures, it is advised to first conduct research on models to determine alternative solutions before deciding on the best alternative, and in order to reveal the optimum economical boundaries and the feasibility of the project. For these aims, one of the modeling methods used for technological purposes is geometric modeling, in which the similarities between the model and a scaled prototype of the model are considered. In other words, there is a fixed ratio between the corresponding points for any specific feature in a coordinate system. In rock masses, these models are made from discontinuity intersection lines as 2D and 3D networks. In many geomechanical models, the most commonly used geometrical features are spacing, orientation, and trace length of discontinuities, which have been defined in detail previously (ISRM, 1978). The discrete element method (DEM) is a widely used modeling technique in rock engineering applications. Thefoundation of the DEM was first developed by Cundall (1971). Several researchers (Hocking, 1977; Williams et al., 1985; Pande et al., 1990; Shi, 1996; Jing, 1998) then introduced additional aspects of the DEM in different related engineering problems. The key concepts of the DEM are that the domain of interest is treated as an assemblage of rigid or deformable blocks/particles, and that the contacts between them need to be identified and

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