Land slides Flashcards
What is Mass wasting?
the spontaneous downslope movement of soil or rock material primarily under the influence of gravity.
What is a Landslide?
a term for a mass wasting event.
Define the term Failure planes.
Weak zones where slope is likely to give way first.
What is the likely outcome of a block on a slope where the Shear force is substantially greater than the shear strength?
The block is very likely to move. Which may lead to a mass waste event.
Apart from the type of material on a slope, what is the other most important factor controlling a landslide’s strength?
The amount of water that the material contains.
What are some Other factors that lead to an increase in shear stress:
Undercutting of slopes: increases the slope angle.
Loading of slopes (e.g., water, snow, or sediment): increases the weight of earth materials
Earthquakes or man-made vibrations: transient and instantaneous increase in stress
Regional tilting: increases slope angles over large areas
The balance of shear and normal forces depends on _______?
Slope angle.
What is a dip slope?
Where Sloped bedrock is inclined and is somewhat parallel to the slope.
What are some Mass Wasting Triggers?
Rain/snowmelt, e.g., Sudden increases in temperature lead.
Over-steepening by erosion.
Overloading (e.g., weight of water, buildings).
Earthquakes.
Weathering. i.e. Erosion.
List the Types of Mass Wasting
- Soil/Earth Creep - Rates ~ 0.1 and 15 mm/year.
- Slides
- Debris Avalanches
- Flows
- Falls
Define Slump landslide.
A landslide consisting of a mass of material moving downslope as a unit, usually along a curved plane of failure.
What are four ways Humans Exacerbate Landslide Hazards.
Forestry:
Mining:
Urban development:
Cut/fill terracing may be unstable.
Extra weight on slopes.
Irrigation, poor runoff management.
Removal of vegetation.
Landslide Hazard Mitigation and Preparation needed?
Prediction/Warning: (e.g., Bare scarps, Tension cracks, Scalloped slopes, Hummocky slopes, Deposits, Tilted or bent trees) as well as the use of warning systems such as GPS receivers to warn if movement begins.
Define Hummocky slopes
“bumpy” ground that has been produced by mass-weathering over time.
Prepare and mitigate for landslide hazards?
hazard maps and appropriate zoning.
relocating communities if deemed uninhabitable due to risk of slides.
mandate geotechnical investigations before development.
Engineering methods e.g., Slopes stabilized via drainage, grading, bolting, piles, retaining walls, shotcrete, etc.
Educating landowners and the public.
