What are the Other Methods of Circular Arc Analysis?
What are the Other Methods of Circular Arc Analysis?
A slope in a soil mass is encountered when when the elevation of the ground surface gradually changes from a lower level to a higher one. Slopes may be either artificial, man-made ( temporary excavations or embankments) or natural ( hill sides, valleys or river cliffs). The slope mass has a tendency to slide down or we can say land sliding. The principal factor causing such a sliding failure is the self weight of the soil. Circular Arc Analysis is one of the analysis for the stability of slopes.
Experience and observations of failures of embankments constructed over relatively deep deposits of soft soils shown that when failure takes placed, embankment sinks down, the adjacent ground rises and the failure surface follows a circular arc as shown in the figure below. That's why, this is called as circular arc failure.
Picture showing circular arc forming after failure of embankment constructed over soft soil
There are several methods for that can be used to perform a circular arc stability analysis for an embankment over soft soil. The simplest basic method is known as Normal or Ordinary method of slices. For this method, the failure surface is assumed to be a circular arc as discussed above.
Ordinary/ Normal method of slices: The ordinary method satisfies the moment equilibrium for a circular slip surface, but neglects both the inter slice normal and shear forces. The benefit of this method is its simplicity in solving the Factor of Safety (FOS) since the equation doesn't require the lengthy iteration process.
Some points in this method are:
Considering moments about O, the sum of the moments of shear forces T on the failure circular arc must be equal to the weight of the soil mass.
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