Terrain Management With Shelly Higman Flashcards
What is a landslide? How are they classified?
Any downward movement of rock, categorized by material type and type of movement.
What is the most common slide?
A debris slide: fairly shallow, 1-2 m depth. Deposits debris as terrain flattens.
What is a the name for a bigger slide where the ground rotates as mass slumps downward?
Rotational slump: Classic features include failure plane, head, foot, toe, scarp, transverse faulting, transverse ridges (conversion of slump to flow).
What is a common cause of failure?
Plugged culvert
What is a common coastal slide triggered by heavy precipitation events?
Debris flow: no internal structure. Quick and violent with a long range. Gullies are at increased risk.
Gully definition
Defined channel with stream with at least 1 100 m reach
Fan to apex gradient of 25% or more
What soil instability factor describes slow movement of soil?
Soil creep: has not yet failed but can lead to future failure
What are the mechanisms that govern the safety factor system?
Driving forces
Resisting forces
Describe driving factors
Inherent factors: soil composition and structure
External factors: undercutting and seismic force
Explain resisting forces
Shear strength
Inherent factors: strong or weak soil, soil types
External: weathering, pore water pressure
What is the strongest material on the coast?
Till: sediment size from clay to boulders, compacted by years of ice, Unsprted
Another strong soil type?
Colluvial: Gravity deposition, sharp edges, Unsorted
Next strongest after collivial?
Glacio fluvial
Worst soil type for stability
Glacio- lacustrine
Contributing factors
Elevation: snow and rain on snow are frequent contributors
Hydrologic region: wet or dry
Slope geometry: gradient (convex catches water), shape (the smoother the worse)
