17 / 09 / 2012

Laser scanner technique to quantify randomness in cube and cubipod armor layers

Jorge Molines Llodrá, Maria P. Herrera, Vicente Pardo, Tomás J. Pérez, Josep Ramón Medina

Most concrete armor units (CAUs) are designed to be placed randomly; however, CAUs can also be placed uniformly, patterned or oriented (Dupray and Roberts, 2009). When CAUs are not randomly placed, special attention is given to the placement technique, construction monitoring and the differences between small-scale models and prototypes. When CAUs are placed randomly, less attention is usually paid to the placement technique, which might give the impression that random placement is easy to achieve, but it is not. In the case of randomly placed CAUs, armor randomness is not considered when testing small-scale models and it is not monitored at prototype scale; thus, model effects may be significant. What does “random placement” mean? Quantitative measurement of armor unit randomness is not available for small-scale models or prototypes. Conventional cube CAUs are supposed to be placed randomly, but it is obvious that cubes tend to position one face parallel to the underlayer slope and to the faces of neighboring units. In this paper, the methodology proposed by Medina et al. (2011) is used to measure the armor randomness, valid for CAUs with three orthogonal symmetry planes such as cube and Cubipod CAUs. The armor randomness is characterized by three Armor Randomness Indexes (ARIs) associated with the different orientations between CAUs and the underlayer slope plane.