EOSC 210 Final Test Questions with 100% Correct Answers
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EOSC 210
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EOSC 210
EOSC 210 Final Test Questions with 100% Correct Answers
What measures can be taken to prevent landslides? - Answer- landslide types like debris flows and rockfall can't be prevented and therefore the strategy is to accept they will happen at some unknown time in the future and protect homes and...
EOSC 210 Final Test Questions
with 100% Correct Answers
What measures can be taken to prevent landslides? - Answer- landslide types like
debris flows and rockfall can't be prevented and therefore the strategy is to accept they
will happen at some unknown time in the future and protect homes and infrastructure
against them with barriers or containment
slope stability analysis: what is factor of safety? - Answer- it represents the ratio of the
forces resisting failure to the forces driving failure.
FS= resisting forces (shear strength) / driving forces(shear stress)
whenFS> 1represention stable situation. shear strenght is greater than the stress.
strength increases/ normal stress as you add more confinement.
shear stress is a function of cohesion and and friction (angle in which the normal stress
is applied) when τ >= c+σ⋅tan(ϕ) failure occurs.
factor of safety formula in terms of shear strength ? - Answer- shear stress is a function
of cohesion and and friction (angle in which the normal stress is applied) when τ >=
c+σ⋅tan(ϕ) failure occurs.
FS=τF/ τ= c+σ⋅tan(ϕ) /Wsina
when slope is steep: more shear stress (chair slides easily) and less normal stress (the
person sitting on the chair at an included has less normal stress )
What is the role of water in promoting landslides? - Answer- It counteracts the normal
stresses that help to engage frictional shear resistance along the sliding surface
what is factor of safety when water is added? - Answer- FS=τF/ τ= c+(σ-u)⋅tan(ϕ) /Wsina
(σ-u)=σ' effective stress= total normal stress-pore water pressure(u)
When there is high pore water pressure (u), it tends to reduce the effective stress in the
soil, potentially leading to a decrease in the shear strength and, consequently, a
decrease in the factor of safety
, what are landslides trigger? - Answer- A landslide trigger is an event that initiates the
movement of soil, rock, or debris down a slope, resulting in a landslide
by
-rapidly increasing stress
-reducing the stregth
-intense rainfall
-rapid snowmelt
-water level change
-volcanic eruption
-earthquake shaking rapid-rockslides weakens the internal structure of slope and induce
shear stress.
- erosion
-anthropogenic
Landslide mitigation measures? - Answer- Avoid the problem: relocating areas of
hazard. look at landslide probability maps, runout distance, not covered by insurance.
prevention: reduce shear stress or increase shear strength. remove unstable material.
Apply anchors, increases normal stress increasing FS. Draining system/artesian it
stabilizes slopes
Protection: protective structures. Barrier systems or rockfall nets. Debris flow protection;
add barriers to remove debris from flow, concrete line Chanel( prevent debris from
flowing along) and boulder embedded Chanel (reduce flow and erosive )
What are the 5 primary geological factors that can be singled out? - Answer- 1. Tunnel
instability mechanism: shows level of in-situ stress and fractures
-Discontinuities: breaks, fractures, or surfaces of separation within rock masses or soil
deposits.
-Quality of the tock mass: Rock quality designation (ROD)- A Higher percent, less
fractures
In situ stress: pre -existing stresses are redistributed. Total stress= In situ stress+
excavation induced stress
water inflows; when water is under pressure it can reduce the effective stress reduce FS
leading to instabilities and failure
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