Mass Movement

Cards (17)

what is a mass movement?
the downslope movement of material under the influence of gravity
what are the six main mass movement processes?
creep, heave, subsidence, fall, slide and flow
what is fall?
the downward movement of material through the air
when does fall occur?
when rocks become detached by weathering processes
what is slide?
when blocks slide and rotate but remain intact and coherent
where does slide occur?
along a well defined shear plane
what are the two types of slide?
rotational / slumps (slow) and transitional (fast)
what is flow?
when there is no well defined shear plane
name four factors which will promote failure?
shear strength, forces acting on the slope, slope materials and slope stability
what is shear strength?
the ability to resist deformation and fracture without failure
what is shear stress influenced by?
the stress applied, cohesion of material and the clay content of soils
what are the three forces/stresses acting on a slope?
vertical, shear and normal
what is the threshold angle of stability?
the shear plane angle at which failure occurs
what is the angle of repose?
the maximum angle that can be attained before it slides
how does water affect slope stability?
adds weight, acts as a lubricant and affects the slope angle that remains stable
what is slope stability?
the relationship between driving and resisting stress
what is the safety facto of a slope?
the ratio between its shear stress and shear strength