Definition of potential volumes of breakage in rocky slopes.

The potential volume of breakage in a rocky escarpment usually addressed by rational or empirical methods (based on the frequency of events). Due to the extension of the rocky escarpments, a large number of data to manage, the range of guidance and strength seam and the interest to characterize the rock mass in an spatial distributed way, a statistical approach based on the treatment of high resolution images will be made.

It is not intended to eliminate all uncertainties in detachment susceptibility assessment, but reduce some of them. Especially those related to the size of the kinetically unstable masses and the spatial distribution of discontinuities.

The specific objectives are:

- Obtaining distribution of volumes kinematically unstable rock masses on a rocky escarpment. It is intended to work with three-dimensional models of the rocky escarpment obtained by photogrammetric techniques and TLS (Terrestrial Laser Scanning). The discontinuities that limit the potentially unstable rock volumes will be characterized on these 3D models.

- Characterization of the predominant failure mechanism in rocky cliffs. The simplest cracks are those that occur through a single surface (planar fracture) or by the intersection of two of them (breaking wedge). Other cracks are complex and take place through stepped surfaces, requiring prior or simultaneous bridges between existing rock discontinuities subparallel break. Complex cracks are less common and more difficult to predict. We intend to characterize the predominant failure mechanism from the analysis of detachment scars and holes in the surface of the cliffs.

- Determination of maximum size. The size of simple cracks, as the planar kind, determines the extent and persistence of unfavorable discontinuity. Many cracks develop in areas whose continuity is interrupted by the presence of another plane, reducing the volume of mobilized mass. Other times, even with the interruption, breakage develops into stepped surfaces, noticeably parallel planes. There are no indicators to provide the type of break (simple or complex). A detailed study about the role of rock bridges (areas where the seals lose persistence and remains relatively intact rock) will be necessary.

References:

Santana. D., Corominas. J., Mavrouli O., Garcia-Sellés, D. 2012. Magnitude-Frequency relation for rockfall scars using a Terrestrial Laser Scanner. Eng. Geology, 145–146: 50–64 Full Paper