After learning about landslides, we shall move on to learn more about rockfalls!
And here is a detailed summary of what we have to know abour rockfalls. (:
Rockfalls
Rockfalls occur on slopes of at least 50-90 degrees. It occurs when the angle of friction is greatly exceeded, overcoming the internal strength of the rock, thus causing the rock to fall. The particle or rock fragment would first become detached then it starts falling, rolling and bouncing until it reaches a point where it can come to rest ( where the slope angle is low enough). This movement causes rockfalls and rock toppling. Most falls involve individual fragments which disintergrate on impact, but occasional major slope collapses take place.
Rockfalls result in :
(a)recession of steep rock walls
(b)resultant slope form is mainly free face and rectilinear or constant gradient slope
(c)scree slope can be concave
(d)talus slope have a high angle of repose,35-40 degree
Causes of rockfalls
1) Geological weakness
-presence of joints, faults and fissures offer lines of weakness along which detachment of blocks is facilitated.
-allow for weathering processes like freeze-thaw or freeze wedging to take place which will subsequently result in rock falls of felsenmeers.
-lines of weaknesses cause the shear strength to decrease
2)Weathering processes
-frost action
-thermal disintegration
-water pressure in pores and joints
-climate related processes thus seasonal pattern of rock fall is present
-maximum in spring and autumn
-gravity plus structural weakness causes the rocks to fall after acted on weathering actions
3) Earthquakes
-quakes and vibrations resulted in increase in shear strength stress and cause imbalance
-hence triggering major rock falls
4) Severe Storms and Heavy Rainfall
-pore water pressure
-role of water in freeze-thaw action
And here is a detailed summary of what we have to know abour rockfalls. (:
Rockfalls
Rockfalls occur on slopes of at least 50-90 degrees. It occurs when the angle of friction is greatly exceeded, overcoming the internal strength of the rock, thus causing the rock to fall. The particle or rock fragment would first become detached then it starts falling, rolling and bouncing until it reaches a point where it can come to rest ( where the slope angle is low enough). This movement causes rockfalls and rock toppling. Most falls involve individual fragments which disintergrate on impact, but occasional major slope collapses take place.
Rockfalls result in :
(a)recession of steep rock walls
(b)resultant slope form is mainly free face and rectilinear or constant gradient slope
(c)scree slope can be concave
(d)talus slope have a high angle of repose,35-40 degree
Causes of rockfalls
1) Geological weakness
-presence of joints, faults and fissures offer lines of weakness along which detachment of blocks is facilitated.
-allow for weathering processes like freeze-thaw or freeze wedging to take place which will subsequently result in rock falls of felsenmeers.
-lines of weaknesses cause the shear strength to decrease
2)Weathering processes
-frost action
-thermal disintegration
-water pressure in pores and joints
-climate related processes thus seasonal pattern of rock fall is present
-maximum in spring and autumn
-gravity plus structural weakness causes the rocks to fall after acted on weathering actions
3) Earthquakes
-quakes and vibrations resulted in increase in shear strength stress and cause imbalance
-hence triggering major rock falls
4) Severe Storms and Heavy Rainfall
-pore water pressure
-role of water in freeze-thaw action
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