Runout Velocity Research Articles

Landslide susceptibility assessment in expansion areas of the rapidly growing city of Cuenca (Ecuador)

Landslides can have significant effects on settlements and human life, especially when mobilized volumes are large and runout velocity is high. In case of high- intensity events, landslide mitigation is not always possible so that the best way to prevent disasters is to reduce the exposed value in susceptible areas. Landslide risk assessment is a fundamental tool for reducing loss induced by landslides, especially considering the impact of high-intensity landslides on the socio- economic development of developing countries. Risk mitigation requires, at least, to be based on a susceptibility scenario and on inventory of existing settlements. On this basis, a study concerning landslide impacting settlements in the city of Cuenca (Ecuador) has been carried out using a landslide inventory database (LID) and supply energy contract database representing a proxy of buildings presence. The susceptibility analysis indicates that most of the slope surrounding the city of Cuenca, where the greatest urban expansion has taken place, is highly prone to instability. In addition, multi-temporal supply energy contract analysis highlights that expansion of urban areas is occurring at a steady rate and such extension is corresponding to an increase in areas susceptible to landslide.

Influence of flow resistance stresses on debris flow runout

The hydrodynamic modeling of debris flows is challenged by the complicated mechanism of debris flow and the large variability of material composition. Therefore, in the dynamic continuum modeling of debris flows it is essential to select suitable rheological and associated friction parameters. The quadratic rheological model is the most comprehensive approach because it considers the effects of viscous behavior, solid-particle resistance, turbulent properties, and friction characteristics of debris flow. Therefore, this study adopted the quadratic model as the governing flow resistance stress and analyzed the influence of various flow resistance stresses to evaluate the runout performance. The shallow-water equations with modified bottom friction were discretized and the developed model was validated against a dam break flow and a ‘spreading of circular cone’ problem. Then, to investigate the relationship between the flow resistance relations and the bottom shear stresses exerted by the cones and dry bed, the model was applied to runout in a rectangular domain with three cone-shaped obstacles. An actual field runout event that occurred in Korea in 2011 was replicated and the runout paths and flow patterns were analyzed according to the various resistance stresses. By considering both the extremely rapid runout velocity and the striking run-up height, the results obtained by the quadratic stress relation achieved the best performance. However, for the successful application of the quadratic approach, three parameters had to be adjusted with consideration to locality.

Study of Flow Balance and Temperature Evolution over Multiple Aluminum Extrusion Press Cycles with HyperXtrude 9.0

In this research, transient finite element simulations of the aluminum extrusion process have been performed in order to study how process parameters influence flow balance and exit temperature. This has been achieved by investigating the influence of billet taper, front billet temperature and ram speed on the run-out velocity and temperature of two separate outlets. Analysis of variance (ANOVA) has been employed to study the effect of each parameter on the velocity and temperature variation of the extruded section. Results show that increasing each of these three parameters results in an undesired increase in exit velocity and temperature. The front billet temperature is found to be the most significant factor affecting the variation. The finite elements software used was Altair HyperXtrude 9.0.

A Multidisciplinary Methodology for Hazard and Risk Assessment of Rock Avalanches

A quantitative procedure for hazard and risk assessment of large landslides that can develop as rock avalanches is discussed in this paper. Reference is made to the IMIRILAND project, where a multidisciplinary methodology has been developed paying particular attention to the landslide modeling process that leads to the quantification of the hazard, i.e. the prediction of the occurrence probability, the involved area and the run-out velocity. The risk assessment methodology is exemplified in the paper with reference to two cases: the Ceppo Morelli and Rosone landslides, both of which are located in the Italian Western Alps. The results of these applications show that, despite the development of sophisticated 3D numerical methods, many uncertainties still remain in the process of modeling large and complex landslides, related in particular to the definition of the probability of failure and the rheological parameters to be used for the prediction of rock mass behavior. However geo-mechanical models are found to be very valuable tools to verify, from a mechanical point of view, the assumptions introduced through the geo-structural and geo-morphological analyses concerning the volume and the kinematics of the unstable mass, and their role is fundamental for the determination of the involved area when mechanical parameters can be assumed with sufficient reliability.