Editing Geotechnical engineering (section)

==Observational method==

First proposed by [[Karl Terzaghi]] and later discussed in a paper by [[Ralph Brazelton Peck|Ralph B. Peck]], the observational method is a managed process of construction control, monitoring, and review, which enables modifications to be incorporated during and after construction. The method aims to achieve a greater overall economy without compromising [[safety]] by creating designs based on the most probable conditions rather than the most unfavorable.<ref>Nicholson, D, Tse, C and Penny, C. (1999). The Observational Method in ground engineering – principles and applications. Report 185, CIRIA, London.</ref> Using the observational method, gaps in available information are filled by measurements and investigation, which aid in assessing the behavior of the structure during [[construction]], which in turn can be modified per the findings. The method was described by Peck as "learn-as-you-go".<ref name="peck">Peck, R.B (1969). Advantages and limitations of the observational method in applied soil mechanics, Geotechnique, 19, No. 1, pp. 171-187.</ref>

The observational method may be described as follows:<ref name="peck" />

# General exploration sufficient to establish the rough nature, pattern, and properties of [[Deposition (geology)|deposits]].
#Assessment of the most probable conditions and the most unfavorable conceivable deviations. 
#Creating the design based on a working hypothesis of behavior anticipated under the most probable conditions.
#Selection of quantities to be observed as construction proceeds and calculating their anticipated values based on the working hypothesis under the most unfavorable conditions.
#Selection, in advance, of a course of action or design modification for every foreseeable significant deviation of the observational findings from those predicted.
#Measurement of quantities and evaluation of actual conditions.
#Design modification per actual conditions

The observational method is suitable for construction that has already begun when an unexpected development occurs or when a failure or [[accident]] looms or has already happened. It is unsuitable for projects whose design cannot be altered during construction.<ref name="peck" />