Chapter 7

Question 1

LandSlides and Mass Wasting Definition: What does that include

Answer 1

Any movement or displacement of soil or rock down-slope under gravity
Includes: Landslides Debris Flow, Soil Creep and Rock Falls

Question 2

LandSlides and Mass Wasting are not as hazardous as what?

Answer 2

Earthquakes or Volcanic activities
-Yet cost US up to 2 billion/year
-Occurs everywhere in the world on almost every unstable slope

Question 3

Classification of Landslides: What are the main three criteria

Answer 3

Type of material ex rock or soil
Mechanism of movement ex sliding, flowing, falling
Velocity of movement ex fast or slow

Question 4

Summary of Landslides: First

Answer 4

Slides:
-Slump(slow)
-Slide/glide(fast)

Question 5

Summary of Landslides: Second

Answer 5

Flows
- Avalanche (fast)
- Creep (slow)

Question 6

Summary of Landslides: Third

Answer 6

Falls
- Mostly fast

Question 7

Explain slumps

Answer 7

Slumps
-are the most common landslides
-Moves on curved, concave upward surfaces, spoon-shaped surfaces
-Vary in size form meters to kilometers
-Involves mainly weathered geologic materials

Question 8

ExplainSlide/Glide

Answer 8

Slide/Glide
- Involves large masses of rocks
-Move along sliding planes
-Mainly sedimentary bedding planes

Question 9

What are the conidtion for Landslides

Answer 9

Condition
-Bedding should be inclined less steeply than inclination of natural(if the bedding is most steep then the slope, then a landslide will occur landslide)

Question 10

Causes of landslides

Answer 10

-Gravity:is driving force for sliding
frictional forces: are resistive forces against
sliding
If
- GRAVITY > RESISTIVE FORCES = sliding

Question 11

Certain Factors increase driving forces & promote sliding: Which are?

Answer 11

• Increase in slope angle:
  -Lack of lateral support:
  -Added weight at the top of the slope

Question 12

Certain Factors reduce strength of slopes and thus reduce resistance
to sliding: Which are?

Answer 12

-Infiltration to produce ground H2O
-Weathering of minerals and rocks
-Burrowing animals
-Excavation of slopes

Question 13

Stabilization of landslides:Water Drainage and Control

Answer 13

In places with a lot of H2O subsurface, construct horizontal
drains to remove water from soils
b. Excavation and Redistribution :
-Reconstruct slope: remove materials from top to bottom
-Toe may be removed and replaced with compacted soils
i.e., TOE BUTTRESSED
c. Retaining Devices:
-Using stones, concrete, etc. buttress the toes of slopes

Question 14

Evidences of past/possible landslides:

Answer 14

Slope> 27°
bumpy convex upward slopes,
springs, wet areas, water-loving plants (i.e., H2O
saturation),

Question 15

Evidence of creep:

Answer 15

-Telephone poles and fences tilting down-slope
-Cracked retaining wall, bent bases of tree on slope, etc.