A PROPOSAL ON ESTIMATION OF VALUE OF IN-SITU GEOLOGTVCAL INVESTIGATION FOR UNDERGROUND CONSTRUCTION PROJECTS

Abstract

It is well-known that underground construction project often include various riskfactors which cause cost variation in the construction process. Among the various factors, this studyfocuses on unforeseeable geological condition in underground construction projects such as tunnels and rock caverns. In general, though in-situ geological survey such as boring are conducted prior to construction, in order to investigate geological condition. However, the method to evaluate the value of in-situ geological investigation is not established yet.From such a viewpoint, this study adopts the methodology that models the uncertainty of the geological conditions as probability function by using by using indicator-kriging, which is a method of geostatistics. And this paper also presents the basic concept to estimate the variation of the construction cost obtained from evaluation of foundation by risk-curve, which is normally adapted in the fmancial engineering.In addition, this study performs a case study on such ways to demonstrate how geotechnical risk affects the construction cost of an actual rock cavern construction project, and examinesthe return on investment of investigations based on the insights obtained from the case study. Finally, results points out that the proposed method is very effective to clearly quantify the value of in-situ geological investigation such as boreholes.