A study on estimation of construction cost variation of underground construction projects caused by geo-technical risk factors

Focusing on mechanical factors that contribute to geotechnical risk, this paper sheds further light on the geostatistics-based evaluation of relationship between the investigation cost and construction cost variation caused by geotechnical risk. In addressing mechanical factors, which often take the form of discrete data, e.g. rock mass classifications, a method of applying indicator kriging is proposed here, where measured values are used as thresholds to estimate their probability distributions. The paper then presents a case study on this methodology to demonstrate how geotechnical risk affects the construction cost of an actual tunnel construction project, and examined the return on investment of in-situ investigations based on the insights obtained from the case study.