The Muir Wood lecture at the WTC 2016 in San Francisco will be given by Prof kaiser on the theme of Ground Support for Deep Underground Construction - Challenges of managing highly stressed ground in civil and mining projects. 

For the economic and safe construction of deep tunnels, a contractor has to be presented with efficient and effective support systems, i.e., support classes that can be rapidly installed and are effective in managing stress-fractured ground. For this purpose, it is necessary to properly anticipate the actual rock mass behaviour and to provide flexible but reliable means of ground control. In mining, mining-induced stresses changes further damage rock near excavations and excessive rehabilitation often causes undesirable delays and costs. In these situations, a deformation-based support design approach is needed to prevent overloading of the rock support system by excessive deformations and to sequence the support installation for optimal support performance.

In conditions where stress-driven failure produces a zone of fractured rock near an excavation, engineering for constructability basically involves three aspects: (1) retention of broken rock near the face; (2) control of deformations due to the bulking of fractured rock, and (3) dissipation of energy if failure occurs in a violent manner.In practice, robust engineering approaches that handle these three aspects well facilitate cost-effective construction processes by ensuring that all construction tools work well.

Within this framework, the lecture will focus on the following technical topics:

-      overcoming challenges in rock mass strength determination for deep excavations;

-      understanding limitations of standard rock support design approaches;

-      overcoming challenge of deformation control in tunnels experiencing static and dynamic failure processes; and

-      selecting efficiently and effective support systems for economic construction.

The author draws on experiences in deep mining and Alpine tunnelling where static and dynamic failure processes caused shallow and deep-seated rock mass failure. Findings from collaborative research and “real world” experiences will be merged to highlight sound engineering design practices that respect the reality of construction and the demand for workplace safety.

The primary conclusion highlights the need for improvements in better anticipating the rock mass behaviour at the tender stage and the need to design ground control measures from a perspective of practicality and deformation compatibility.