A New Method for In-situ Non-contact Roughness Measurement of Large Rock Fracture Surfaces |
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| Authors: | Q Feng N Fardin L Jing O Stephansson |
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| Institution: | (1) Engineering Geology and Geophysics Research Group, Department of Land and Water Resources Engineering, Royal Institute of Technology, Stockholm, Sweden, SE |
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| Abstract: | Summary
This paper presents a new method for in-situ non-contact measurements of fracture roughness by using a total station (TS).
The TS is a non-reflector geodetic instrument usually used for measuring control points in surveying and mapping. By using
a special-developed program, the TS can be used as a point-sensor laser scanner to scan a defined area of the fracture surface
automatically, in field or in laboratory, at a distance away from the target surface. A large fracture surface can be automatically
scanned with a constant interval of the sampling points, both within a defined area or along a cross-section of the exposed
rock face. To quantify fracture roughness at different scales and obtain different densities of the scanned points, the point
interval can be selected with the minimum interval of 1 mm. A local Cartesian co-ordinate system needs to be established first
by the TS in front of the target rock face to define the true North or link the measurements to a known spatial co-ordinate
system for both quantitative and spatial analysis of fracture roughness. To validate the method, fracture roughness data recorded
with a non-reflector TS was compared with the data captured by a high-accuracy 3D-laser scanner. Results of this study revealed
that both primary roughness and waviness of fracture surfaces can be quantified by the TS in the same accuracy level as that
of the high accuracy laser scanner. Roughness of a natural fracture surface can be sampled without physical contact in a maximum
distance of tens of meters from the rock faces.
Received May 24, 2001; accepted July 24, 2002; Published online November 19, 2002 |
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| Keywords: | : Roughness waviness primary roughness fracture surface geodetic non-reflector total station laser scanning large fracture surface in-situ measurement |
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