Chisels are used in more difficult ground. Once disturbed the samples can be retrieved to the surface using a shell. On site - tests performed on site insitu and often combined with visual examination. A steel plate of a known surface area is jacked against a fixed kentlidge, or loaded, and the settlement is accurately measured with a dial gauge. This test assists in calculating the soils bearing capacity.
Test assesses the relative density of the soil.
These and possibly other tests, will tell the designer what sub structure type is most suitable for the discovered ground conditions. Rock - easily identifiable, very stable, requires mechanical excavation. Requires a pick for excavation. Sands may be prone to frost heave, particularly fine sands. Hazards with silts are as per sand.