Trial Pits and Borings

Trial pits consist of making excavation at site enabling examination of the subsoil and collection of samples. This technique could be adopted for small depths of about 3 m. The depth of exploration needed to be carried out is generally, one and half times to double the width of the foundation.

For deeper exploration, borings have to be carried out. These could be auger boring, rotary boring, percussion boring, etc. From these borings, undisturbed/disturbed soil samples could be collected.

The samples collected from the pits/borings are listed in the laboratory to assess the several properties such as grain size distribution, liquid and plastic limit, specific gravity, natural moisture content, unit weight of soil, compressive strength and etc. From these investigations, a chart denoting the depths of several strata could also be prepared.