Building Construction
Engineering news formula for obtaining safe bearing capacity of pile for drop hammer, is,

Q = (W × 2.5)/6 (S + h)
Q = Wh/6 (S + 2.5)
Q = (W × 6)/h (S + 2.5)
Q = Wh/2.5 (S + 6)

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Building Construction
During percussion drilling

The soil to a considerable depth below the bottom of the hole gets disturbed
Ground water observations are hindered due to entry of the slurry in the soil below the bottom of the hole
All listed here
Caving or mixing of strata are caused in soft soils or cohesion-less soils

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