(Metrum [Online]. Available from: http://www.metrum.lv/en/where-we-work/geology/subsoil-trial (Accessed February 2nd, 2017))
Geological surveying is crucial before starting the construction phase, this is due to the fact that even though the surface examination is very valuable, the subsurface must be evaluated, which is done through boring or digging exploratory holes. And the extent on the survey will be determined by the importance of the structure proposed, for example, for projects which puts heavy load on the soil, the aim of soil exploration in this instance would be to provide data that will help in the selection of proper types of foundation.
The purpose of this survey are to determine:
- the properties of the soil
- the material properties that are required in construction
- the conditions of ground water
- the cause of fault and failures of exiting constructions
Stages of Sub-Surface Investigation:
1- Reconnaissance Study:
- Geological Data
- Serial Photography
- Pedological Data
This stage involves preliminary feasibility study, which is done before any detailed planning. With the main objective of exploration being to obtain rough idea about the soil type in the area.
2- Detailed Investigation:
- Boring
- Sampling
- Testing
- Lab Test
- Field Test
- Aerial Photographs
- Geographical Methods
3- Performance Study:
- Further Testing
- Instrumentation
- Performance Evaluation