The Observational Method was proposed in 1948 by Karl Terzaghi and describes a continuous and integrated process of design to achieve greater overall economy of construction, without compromising safety.
The method focuses on designing earth structures based on the most probable, rather than the most unfavorable, possibilities. The uncertainties due to lack of available geotechnical information is balanced by observation of the soil and structural movement throughout construction.
The Observational Method can be described as follows:
- Geotechnical properties are established using site investigation and laboratory testing.
- A design is proposed based on the most probable, rather than the most unfavorable, conditions. Areas of concern are analyzed using engineering theory and experience.
- Models are created to predict behavior.
- The structure is monitored throughout construction to verify design assumptions and performance.
- Design is modified when required, based on actual site conditions.