8/8/2019 Abstract Geomin 2011 Gamboa Poetsch

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THE APPLICATION OF 3D IMAGING FOR ASSESSING THE GEOLOGIC

SITUATION IN OPEN PIT MINES AND UNDERGROUND EXCAVATIONS

Christian Manuel Gamboa Navarro 1 & Markus Ptsch 2

1. Support engineer at Geodata Andina, Diagonal Paraguay N403 Of 42, Santiago, Chile. Tel +56 02 6334598, email

chgamboa@geodataandina.cl2

. Support engineer at 3G Software & Measurement GmbH, Plddemanngasse 77, 8010 Graz, Austriatel. +43 316 464744, email m.poetsch@3gsm.at

Remote measurement systems have become widely accepted tools in engineering geology to acquire relevant data on rock

excavations and the joint system in the adjacent rock mass. Most of all, 3Dimages are especially suitable to support the

daily engineering geologic work in terms of speed, efficiency, quality, accuracy, and flexibility. 3Dimages comprise both,

a highly accurate, three-dimensional description of the rock surface and a digital photograph aligned with the surface.

This combination allows identifying geologic features visually and subsequently measuring their geometric properties,

such as the spatial orientation, position, spacing, persistence, roughness, etc.

This paper reviews the properties of an image based measurement system and its application in a mining environment,

both in open pit and underground excavations. It especially points out the benefits gained from the integration of

computer vision principles into the traditional stereo-photogrammetric approach including freehand photo-taking, use of

pre-calibrated cameras, use of zoom lenses, use of scale figures instead of control points etc.

3Dimages provide the geometric data which inputs to rock mass characterisation and classification. Apart of individual

measurements the 3Dimage can be assessed thoroughly and parameters such as number of joint sets, mean orientation of

sets, normal set spacing, etc. are provided with built in functions. 3Dimage provide a high number of measurements

leading to statistically significant conclusions, algorithmic assessments and thus objective results, and reproducible

measurements.

Individual measurements of distinctive features can be extrapolated and are used to determine isolated and movable

blocks in the free face of an excavation. The paper outlines the different approaches for using 3Dimages in the

engineering geologic practice.

New developments of the measurement system include merging of single 3Dimages, comparison of 3Dimages for

identifying changes in the rock mass with time, and scaling by a remote projection unit. The application of a remote

projection unit avoids working in the unsupported area of underground excavations.

Figure 2: 3D image of a tunnel face with joints intersecting in the tunnel crown and Figure 2, 3D image of two banks in a

open pit mine.