A well-designed site investigation is a key investment in managing this risk and is a vital step towards completing a successful underground construction project.
FREMONT, CA: As with all engineering and construction developments, tunneling and underground construction projects require good design and thorough planning. Even when an underground construction project is neatly planned at its inception, conditions and demands change during execution. The key to an underground construction project's ultimate success is the identification and management of risks during construction. Embracing technological advances can only increase the understanding of an underground project's geotechnical and hydrogeological setting. Here is more to it.
Underground construction projects naturally face different challenges in relation to their location and setting. When it comes to works involving tunneling, engineers need to understand the strength of the ground and how it will act so that they can determine appropriate design. However, stability analysis and ground support design for underground construction is very challenging areas of practice, requiring careful consideration and keen expertise.
With a multitude of potential instabilities, it is vital to develop a geotechnical and hydrogeological investigation program to obtain the data necessary to decide and assess instability and to inform the design of a stable structure. A desktop study is a primary step in any site investigation program. The study should identify potential geotechnical, hydrogeological, and contaminated land issues and should involve a review of the existing data. If done well, data collected at this stage can have a significant impact on the required extent and cost of the site investigation.
The data needed from a site investigation includes identification of the soil and rock units likely to be encountered, geotechnical and hydrogeological characteristics, the magnitude and orientation of the in-situ stress field, groundwater levels, and pressures at depth, and the quality of existing soil and groundwater. In designing a site investigation program, it is also vital to be aware of the limitations of what engineers can test and fully understand. Additionally, core scanning and borehole geophysical imaging like acoustic televiewer (ATV) and sonic logs are useful methods to improve interpretation of the conditions encountered in the recovered core, the walls of the boreholes and surrounding ground.