Stability of slopes
- rates of mass movements can be altered by human activities:
● building/excavation
● drainage
● agriculture
● accelerated by destabilising slopes
● erosion enhanced by trampling in recreational areas
● crustal loading
● undercutting or overloading
- human influence ---> speed up already existing process rather
than creating a new one
- urban areas:
● slope modification is high - need for safe infrastructure using
suitable engineering
● large modern buildings involve the removal of material to
allow for proper foundations - even in flat land
● slope modification increases with building on increasingly
steeper slopes ---> cut-and-fill technique: creating a terrace
with an oversteepened slope at both sides
- slopes with no vegetation are much more susceptible to slip during
periods of rainfall
Strategies to reduce mass movements
, Falls:
flattening slope
drainage
reinforcement of rock walls - cement, anchor bolts…
covering of wall with steel mesh
Slides and flows:
grading - flatten the slope
drainage of surface water
sealing surface cracks ---> no infiltration
subsurface drainage
using walls to prevent undercutting
Pinning
- attach wire nets/concrete blocks to a rock face/slope ---> reduced
risk of rock falls or erosion
Netting
- collect fragments of material/scree ---> collected at a later date
- used in areas where tourism is important + risk of rock fall is high
pinning
netting
Grading
- rates of mass movements can be altered by human activities:
● building/excavation
● drainage
● agriculture
● accelerated by destabilising slopes
● erosion enhanced by trampling in recreational areas
● crustal loading
● undercutting or overloading
- human influence ---> speed up already existing process rather
than creating a new one
- urban areas:
● slope modification is high - need for safe infrastructure using
suitable engineering
● large modern buildings involve the removal of material to
allow for proper foundations - even in flat land
● slope modification increases with building on increasingly
steeper slopes ---> cut-and-fill technique: creating a terrace
with an oversteepened slope at both sides
- slopes with no vegetation are much more susceptible to slip during
periods of rainfall
Strategies to reduce mass movements
, Falls:
flattening slope
drainage
reinforcement of rock walls - cement, anchor bolts…
covering of wall with steel mesh
Slides and flows:
grading - flatten the slope
drainage of surface water
sealing surface cracks ---> no infiltration
subsurface drainage
using walls to prevent undercutting
Pinning
- attach wire nets/concrete blocks to a rock face/slope ---> reduced
risk of rock falls or erosion
Netting
- collect fragments of material/scree ---> collected at a later date
- used in areas where tourism is important + risk of rock fall is high
pinning
netting
Grading
