Mass Rock Creep (MRC) process is one of the main factors responsible for damaging rock masses in transient tectonically active mountain landscapes. This process encompasses entire hillslopes or valley flanks acting on a large time-space scale, leading as a response to gravitational disequilibrium to slope failures that can generate huge rock avalanches.
Although the limit of theories is represented by the difficulty of accurately estimating the starting time of the process as well as of discriminating the distinct phases, reconstructing the morpho-evolutionary history of the river valley slope is a key to shed light on the evolution of the gravity-induced deformations. Experience in back-analysis of huge rock-failure confirms this requirement stressing the importance of a detailed 2D sequential evolutionary model.
The aim of this project is to set up a quantitative multi-modeling to reconstruct the nonlinearity of the time-displacements relationships as well as the accurate history of the past erosion rate evolution and its nexus with the deforming slopes.
The multi-modeling framework incorporates contributions from morpho-evolutionary modeling, detailed engineering-geological modeling, landscape evolution modeling, and time-dependent stress-strain numerical modeling to analyze the rheological evolution of river valley slopes. The methodological structure is cyclical in that the output of a model becomes the input for the next one.
Experiencing such a multi-modeling approach allows to include in a unique methodology the back-analysis of occurred landslide events and the forecast of slope evolution by considering possible scenarios of suitable destabilizing actions (forced modeling). Moreover, the computed strain rates can be considered to establish multi-hazard scenarios posed by potential evolution of ongoing gravity-induced deformations.
The here presented project allows testing a quantitative multi-modeling methodological approach. The aim is to reconstruct the nonlinearity of the time-displacements relationships as well as the accurate history of the past erosion rate evolution and its nexus with the deforming slope. Such an approach can fill the gap of the difficulty of precisely and accurately estimating the starting time of the MRC process, discriminating the different phases as well as inferring a more suitable evaluation of the elapsing time for failure in creep evolving slopes. Since the complexity of the topic is strictly related also to the rheological behavior of jointed rock masses due to their discontinuous, heterogeneous, and anisotropic nature, and then to the viscosity determination, it can be possible by assessing such parameters to back-analyze occurred landslide events and to forecast slope evolution by considering possible scenarios of suitable destabilizing actions (forced scenario modeling).
It, therefore, represents a useful methodology to analyze the space-time evolution of a slope, introducing the concept of ¿time-dependent risk¿, in which landform evolution allows us to assess multi-temporal hazard scenarios.
Furthermore, the originality of our contribution lies in giving a quantitative value to valley-slope evolution modeling and in a broad sense also to the multi-modeling approach, in which stress-strain analysis alone had this meaning.
The cyclical methodological structure is a great advance in modeling technique since it considers the morpho-evolutionary shaping of hillslopes due to tectonics and surface processes (fluvial and hillslope diffusive processes) and the gravity-induced deformations due to the MRC process.
The hereafter defined modelling cascade, will allow us to adequately consider the role of fluvial and slope waters morphogenesis in the gravitational evolution of mountain slopes and ridges, clarifying the importance of morpho-tectonic and erosional evolutions in slope-to-valley systems in predisposing and preparing (over time) the occurrence of slope failure.
Because of the possibility to achieve 3D reconstruction and the multi-temporal features derivable by LEMs they arise as one of the best tools for conditioning stress-strain numerical analysis and one of the outreaching methods for the comprehension of gravitational dynamics.
As optimum result, the link between LEMs and FEMs models will support multi-temporal seismic analysis of MRC processes, adding a piece of knowledge in the understanding of the causes of acceleration of steady-state creep processes involving slopes. More specifically, the role of recurrent earthquakes affecting deforming slopes over time will be assessed, weighting how and when they can turn the deformation process towards an irreversible end (i.e. a paroxysmal slope failure).