Advanced Geotechnical Investigation and Data Interpretation for Complex Underground Structures

In recent times, development of underground space for variety of purposes is becoming more viable alternative to surface facilities with an ultimate aim of conserving surface space for various reasons and for strategic purposes. However, construction of underground structures continues to be expensive, with project cost rising rapidly and often significantly exceeding the preconstruction estimate. One of the most desirable and optimistic ways to improve the economic feasibility of underground construction is adopting a proper and systematic geotechnical investigation process. As variation in geology plays a dominant role in cost, feasibility, safety, and behavior of underground structure, serious consideration has to be given for geotechnical investigation. As soon as the investigation data is obtained, it should be properly interpreted and evaluated to get a meaningful outcome for greater savings in cost and time through optimum design. The basic objective of this paper is to recommend guidelines for planning and executing an effective multiphase geotechnical investigation program with advanced methods depending on the complexity of project and timely interpretation of the investigation data. This paper highly emphasizes on deriving the stratigraphy, structural features, presence of water pockets, in situ stress condition, and strength parameters through field and laboratory investigations. From this study, geotechnical engineers are expected to achieve a great extent of understanding in interpretation of investigation data and collaborating inter-related geotechnical information to derive the key aforementioned inputs. As a result, this will help in designing adequate support system for the underground structures, eradicating the possibilities of overdesign.