Influence of morphological characteristics of heterogeneous moraine formations on their mechanical behaviour using image and statistical analysis

The study of landslide stability on mountain slopes becomes more difficult when the sliding materials. are heterogeneous. This is a current problem with the old glacial moraines now under study in the Aspe Valley, Pyrenees. Analysis of slope stability numerical models necessitates accurate data about mechanical and physical properties. Because moraines are very heterogeneous, a large sample is necessary, but, unfortunately, data acquisition costs a lot of time and money. Therefore, we would like to estimate mechanical properties from correlated variables that are easier to acquire (morphological variables using image analysis). Observations in the field and previous mechanical results in the laboratory have shown that differences between the behaviour of moraines seem to be related not only to their three-dimensional structure but also to the morphological and petrographical characteristics of their components. The moraines are classified based on textural characteristics at the sample scales based on the distributions of size and shape of their constitutive elements (blocks, matrix, etc.). Then, we study the statistical distribution of the variables to highlight the most significant variables. Next, we evaluate the results of the mechanical behaviour of the moraines, with the internal angle of friction and the effective cohesion. On seven specific moraines, we established relations between the effective internal angle of friction, the elongation factor and the roughness factor. (C) 2003 Elsevier B.V. All rights reserved.