Detection of Fabricated Macropore Networks Using 3-D Laser Scanning.

Recent applications of a new 3-D laser scanning technique known as multistripe laser triangulation (MLT) to detect macropore networks in field excavation walls have not yet been rigorously tested. The goals of this work, therefore, were to determine the sensitivity, detection limits, and reproducibility of MLT images of macropores. The macropores in this study were fabricated in acrylonitrile butadiene styrene (ABS) plastic using a 3-D printer in order to simulate and test situations encountered in ‘real-world’ excavation walls with respect to macropore thickness, angle, and depth. Macropores that represented a combination of four thicknesses (250, 500, 1000, and 3000 μm), four depths (250, 500, 1000, and 3000 μm), three vertical angles (30, 60, and 90°) perpendicular to the scanning plane, and three lateral angles (30, 60, and 90°) parallel to the scanning plane were fabricated and scanned. In addition, effects of excavation wall roughness on the detection of macropore networks was examined by scanning carefully prepared soil monoliths with a range of surface relief. The effects of various post-processing algorithms, procedures, and parameter values on the macropore information acquired were also investigated. Results and implications of this examination will be presented and discussed.