2D Runout Analysis

DAN-W is a Windows-based geotechnical software tool used for dynamic runout analysis of rapid landslides and rock avalanches, based on a theory of runout analysis developed by Hungr (1995).

The program accepts user-input data in the form of path slope and initial sliding mass geometries, and material properties based on eight types of rheologies. For pseudo-three-dimensional analysis, the width of the slide can also be specified.

A Lagrangian solution of the integrated equations of motion is then implemented for thin elements of the flowing mass.

The sliding mass is animated on the screen as the calculation progresses. The model also simulates erosion and deposition of material.

Data input

• Streamlined problem setup
• Simple slope path and sliding mass input
• Up to 20 materials along slide path
• Choice of 8 material rheologies (Frictional, Plastic, Newtonian, Turbulent, Bingham, Coulomb frictional, Power Law, Voellmy)
• Uniform thickness sliding mass option

Analysis

• Fast 2 dimensional modeling with on-screen animation
• Pseudo-3d modeling option with variable channel width
• Entrainment of material along bed surface (erosion and deposition)
• Balistic trajectories possible to simulate slide launching off a drop
• Optional fixed front or rear end-conditions to simulate walls

Data output

• Isometric or 2d thickness and velocity profile animations
• Initial and final slide location, velocity, volume statistics
• Export profile and velocity plots compatible with Grapher and Excel
• Observe slide statistics at a given point along path

Equivalent fluid

DAN-W uses the "equivalent fluid," depth-averaging approach, as described by Hungr (1995). The flowing mass of the landslide is simulated as a mass of simple fluid which is always frictional internally, but with a basal flow resistance developed according to one of several alternative rheological models.

Back-analysis

The rheological properties of the "equivalent fluid" must be determined by back-analysis of real landslide precedents. Back-analysis involves the assessment of the model’s performance in terms of runout distance, length of deposit, deposit thickness distribution, flow duration and distribution of flow velocities, where known in the field, as described in Hungr (1996).

Shallow flow

DAN-W is based on shallow flow assumptions and is best suited to shallow mass movements, where the flow thickness is at least an order of magnitude less than the length of the moving mass and the movement vectors are approximately parallel with the bed.