EOSC 114 Module 4 Practice Questions with Complete Solutions Rated A+
6 views 0 purchase
Course
EOSC 114 Module 4
Institution
EOSC 114 Module 4
EOSC 114 Module 4 Practice Questions with Complete Solutions Rated A+
Mass Movement/ Mass Wasting - Answers refers to downslope motion of soil/rock materials under influence of gravity
Landslide - Answers General term for mass movements - occur when gravity pulling material down slope exceeds slo...
EOSC 114 Module 4 Practice Questions with Complete Solutions Rated A+
Mass Movement/ Mass Wasting - Answers refers to downslope motion of soil/rock materials under
influence of gravity
Landslide - Answers General term for mass movements - occur when gravity pulling material down slope
exceeds slopes material's internal resistance to shear or failure - materials move by sliding or shearing
along weak failure plane or number of planes
2 Components of gravity - Answers Gp - part that acts perpendicular to the slope - helps hold an object
to it's place on the slope
Gt - acts tangentially to slope surface - parallel and down the slope, causes shear stress (more the
steeper the slope is)
Shear Strength - Answers -defined as internal resistance of body to shear stress or a material's internal
shearing resistance
-results cause gravity pulls slope material downslope, force resisting this movement will be induced,
including frictional resistance and cohesion among particles of slop material
Shear Strength Factors - Answers Type of soil/rock
Condition of geologic materials (how eroded)
Presence of weak surfaces (joints/faults)
Pore water pressure within the slope
Safety Fs - Answers Ratio of shear strength at failure Sf to average shear stress T (Sf/T)
-slope failure occurs when gravity parallel to slope (shear stress) becomes greater than the materials
making up the slope which is acting to hold itself in place (shear strength)
-can be thought of as ratio of forces that resist movements to forces that drive movement
if greater than 1, slope is stable, if less, slope failure expected
effective stress - Answers net sum of opposing effects of normal stress and pores water pressure
(normal stress - pore water pressure)
can be viewed as a sum of contact forces between grains, divided by total area
can try to manipulate this to make stopes more stable
, cause - Answers factor that makes slopes susceptible to movement
trigger - Answers event that actually initiates movement by driving FS<1.0
e.g. earthquakes, volcanoes, tons of rain, mining, irrigation, etc
trigger frequency - Answers how often an event occurs that sets off a landslide.
can be natural, human induced, or combo of the two
Erosion - Answers transport of material away from it's source - removing material at base of slope can
cause slope failure in 2 ways:
1) driving mass > resisting mass
2) slope steepness at base increases so shear stress > shear strength
Rapid Erosion - Answers Large storms (heavy rainfall or pounding waves) can work to rapidly erode
undercut coastal slope - large landslides (e.g. UBC 1935)
Vegetation effects - Answers affects shear strength - roots increase soil cohesion and strength by helping
bind loose material
decrease surface erosion by absorbing extra water
Water Content effects - Answers -excessive water increases mass and shear stress
-fluid pressure - reduces friction, slope failure
- water increases weathering of rocks when it flows in narrow rock fractures - freeze thaw cycles can
wedge em appart, fall !!
- water can help or hinder cohesion - helps bind shit, but when too much, can't bind
Precipitation Effects - Answers more frequent landslides after heavy rainfalls (erosion and pore
pressures)
big storms are common triggers
heavy/prolonged rain can increase goundwater levels too - trigger more deep seated/slower moving
landslides (like slumps)
Volcanic Activity Effects - Answers loose ash on hillsides followed by accelerated erosion can be
triggered by intense rainfalls
- historic large langslides
e.g. mt st helens
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller TutorJosh. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $7.99. You're not tied to anything after your purchase.
