KNOWING WHERE PROCESSES ARE HAPPENING
Process models are a mainstay of hazard assessment and action planning, whether it be for large-scale demarcation of process areas or for calculating the impact of a process on a structure. We can deploy a broad range of tried-and-tested process models. GEOTEST Ltd.'s services include:
- Rockfall modelling
- Debris flow modelling
- Unconfined debris flow modelling
- Avalanche modelling
- 1D and 2D hydraulics
Rockfall modelling - Where will the rock land?
Rockfalls and rockslides pose a significant risk to inhabited buildings and many types of infrastructure, not least transport routes. In critical areas, it is important that the potential pathways, jump heights and fall energy of falling rocks are known as accurately as possible. We can calculate these parameters using two different models:
- GEOTEST-Zinggeler model (left)
Over 20 years of experience with proven applications in many European countries and other projects in places such as Chile and South Africa.
Large-scale overview modelling (> 100 km2). Calculates fall trajectories, maximum jump heights and fall energy.
Strengths of model:
Block parametrisation with the three main axes. Simple, intuitive model parameters: ‘Surface roughness’ and ‘Soil elasticity’.
Very realistic modelling of forest influence
- RAMMS model: rockfall (right)
A module in the SLF/WSL software series, available as a beta version since 2014.
Detailed studies of single events with a very extensive range of results: jump heights, energy, speeds, barrier plots, 2D trajectory plots, statistical quantiles, etc.
Strengths of model: Ability to vary starting conditions: offset, block orientation, initial speeds. Very realistic block parametrisation: point cloud with convex hull. Complex approach to contact reaction between block and subsurface: slipping/scarring
Debris flow modelling - Knowing where and how debris flows will occur
Debris/mud flows are extremely dynamic, complex and menacing natural hazard processes. In the steep Alpine terrain, they present a major natural hazard risk, particularly in conjunction with climate change. This risk is of constant concern to the authorities. Geotest Ltd. has extensive experience in managing debris flow hazards.
In addition to the vital task of in-situ process assessment, we also use the two-dimensional RAMMS simulation model, particularly in the planning and design of protective measures. This model helps our experts to assess the flow and deposition characteristics of debris flows. The calculated parameters such as flow depths, flow speeds and dynamic load are then used, among other things, to work out the process intensities and to design the relevant structures.
Unconfined debris flow modelling - Where could a mud slide occur?
The unconfined debris flow process (also referred to as a slope-type debris flow) is calculated in two steps:
The starting zones are modelled using SLIDISP. Based on these, the depositional areas are modelled using SLIDEPOT.
- SLIDISP calculates the slope stability (degree of safety F) for each grid cell based on an infinite slope analysis. For all geological and/or pedological unit areas, the geotechnical parameters of critical friction angles as well as cohesion are first determined and digitalised. Together with the gradient, these values form the central input for the modelling.
- SLIDEPOT is a GIS modelling system that calculates the propagation of the material in the direction of flow based on modelled (or mapped) starting zones. The modelling is based on the reduction in the water content of the unconfined debris flow which occurs during propagation, ultimately bringing the propagation to a halt. For the flow paths, SLIDEPOT also uses an enhanced neighbourhood analysis (focusing on four grid cells in each stage of the propagation). Unlike with a simple single-flow approach, this allows SLIDEPOT to model the direction of propagation with a high degree of accuracy.
Graphic: The depositional zones are modelled based on the dark-red areas (starting zones). The final number of propagation stages and hence the maximum distance of propagation is usually calibrated based on known unconfined debris slope events.
Avalanche modelling - Where will avalanches occur and how powerful will they be?
Avalanches remain the most significant natural hazard risks in winter and spring.
Planners, transport infrastructure operators and tourism professionals want better and more accurate assessments and calculations. We offer the following services:
Hydraulik 1D und 2D - Auf Hochwasser gut vorbereitet sein!
In flachen Gerinnen und Talflüssen treten durch wechselnde Gerinnegeometrien, seitliche Zuflüsse und Fliesshindernisse komplexe Strömungsvorgänge auf, welche die hydraulische Abflusskapazität bestimmen. Durch Anwendung unseres 2D-Strömungsmodells Hydro_AS-2D ermitteln wir für Sie die Abflusskapazität im Gerinne und die exakte räumliche Ausbreitung von Überflutungen unter Angabe von Überflutungstiefen und Fliessgeschwindigkeiten. Mit dem Strömungsmodell können wir Sie zudem für die Berechnung der Flutwellenausbreitung nach Dammbrüchen beraten. Bei Bauvorhaben im Gerinnebereich kann zudem der Einfluss der Bauwerke auf die Überflutungsgefährdung ermittelt werden. Unsere Resultate prüfen wir ergänzend anhand des hydraulischen 1D-Modells HEC-RAS in Kombination mit Geländebegehungen.