Why Landslides happen ?

Why landslides happen?

Because of failure of slopes, So to understand this let's discuss Stability Of Slopes.

·       Landslides are the downward and outward movements of slope materials because of exhaustion of required shear strength (strength of the material against the structural failure)

·       Slope materials are composed of natural rock, soil, artificial fills or combination of all

·       There are 2 causes of slope failure as external or internal.

1.    External slope failure:

·       When increasing in stress at unaltered shearing resistance of the material

·        Because of

Ø gravity force

Ø Earthquake force

Ø  Seepage force

Ø excavation near the slope

Ø  Erosion due to flowing water

Ø Sudden drawdown

2.    Internal slope failure:

·       Lead to slide without any change in a surface condition which involves unaltered shearing stress in the slope materials

·       Such as

Ø Excess pore water pressure

Ø leaching of salt

Ø softening

Ø breakage in cementation bond

 

Note:  The landslides happen because of external or internal failure of slopes

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