Investigations of a Hand-Held Laser Scanner to Estimate Fracture Apertures and Roughness of Natural Rock Formations

Portable Coordinate Measuring Machines (PCMM) are typically used in industrial environ-ments (e.g., for reverse engineering or quality assurance purposes). Accordingly, the captured data usually has to have a high resolution and a small uncertainty, e.g. in the range of micrometer. These requirements also apply to roughness determination of surfaces and volumetric flowrates in pipes and gaps/fractures, especially concerning natural rock formations for hydro-thermal applications. As sandstone is sensitive to tactile contact and shows significant abrasion, non-tactile methods using laser scanners are preferred.
In this context, a handheld laser scanner in combination with an articulated measuring arm is investigated to evaluate, if these requirements could be achieved. As the laser scanner design bases on the principle of triangulation, the related limitations are evaluated. For the determination of nonhomogeneous surface characteristics with high quality and resolution, resp., the sensor perfor-mance is enhanced by using special techniques and a particular hardware design.
Studies have been conducted to estimate the minimum fracture apertures in respect of eval-uating the complete measurement process, data analysis, and traceability to get a reliable result for the estimated value and the uncertainty. ... mehrFurthermore, investigations have been undertaken regard-ing the determination of roughness of a bedding joint and the results have been compared to an established and independent method.