Building Construction
During percussion drilling

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

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Building Construction
Auger boring

Is the most primitive method for making a hole in the ground
All of these
Is most economical up-to a depth of 5 meters
Is generally employed in cohesive and other self soils above water table

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