Test Pits – Soil Exploration
The commonly used method to find the nature of the subsoil strata is to dig a hole and see. The holes which are large enough to permit the entry of persons for inspection are called ‘Test Pits’. The pits are normally square in plane and are dug by hand or by excavating equipment. The dimensions of the pit depend largely upon the depths up to which the excavation is to be made. In cohesion-less soils, the sides of the test pit are sharply sloped. In cohesive soils, at depth below 3 m, bracing is required to keep the sides of the pit vertical.These are comparatively expensive and hence they are only used for structure having shallow foundations (up to 3 meters).