Seminar on: Subsea tunnelling and water control & Tunnelling in special rock conditions 

The NTU-JTC Industrial Infrastructure Innovation Centre organised its fourth seminar on Tuesday, 6th November, 2012.  Dr Kristin H Holmøy and Dr Nghia Quoc Trinh were specially invited from SINTEF, the largest independent research organisation in Scandinavia, Northern Europe.

The first speaker, Dr Holmøy gave a presentation on Norwegian subsea tunnelling concept with emphasis on groundwater control.  Various issues were covered including Norwegian tunnelling concept, groundwater control and the significance of geological parameters for predicting water inflow in hard rock tunnels. Dr Holmøy also presented the solution for water control, main excavation method, and support measures.

Dr Holmøy also presented her eight hypothesises from her PhD studies at Norwegian University of Science and Technology (NTNU), emphasizing on the significance of geological parameters for predicting water leakage in hard rock tunnels, where Dr Holmøy shared the hypothesises that were being supported, and allowed the participants to better understand the concept of subsea tunnelling.

Dr Kristin H Holmøy received both MSc (1993) and PhD (2008) degrees at the NTNU Dept of Geology and Mineral Resources Engineering. She has 20 years of experience in rock mechanics and rock engineering. She has been involved in many major tunnel projects in Norway working on engineering geological mapping, evaluation of rock mass stability, planning and follow-up of pregrouting as well as post excavation grouting. Dr Holmøy is particularly interested in describing weakness zones, investigation methods, water inflow, pregrouting, and excavation methods in poor rock mass quality. Dr Holmøy is currently the chairman of the Norwegian Rock Mechanics Society and the leader of the Rock Engineering Division at SINTEF.

The second speaker, Dr Trinh gave a presentation on Tunnelling in special rock conditions where two case studies were presented. The first case study was tunnelling in extremely poor rock mass condition which caused a tunnel to cave in. The failure resulted in more than six months of construction delay and complicated excavation and support procedures. In this case study, Dr Nghia shared the three simulations ('Excavation without support', 'Excavation with only spiling bolts' and 'Excavation with spiling bolts, steel ribs and shotcrete') used to resolve the cave-in problem.

The second case study discussed about the rock excavation and support for a crusher hall in Rana Gruber, Norway, where Dr Trinh shared the site observations of Rana Gruber and the numerical modelling done for the crusher hall. The structure is the world's largest cavern hall for public use.

In both cases, numerical modelling was extensively used for analysing the rock mass behaviour and to estimate appropriate rock support measures.

Dr Nghia Quoc Trinh received his doctoral degree in rock engineering from NTNU in 2006. He has been working as a senior rock engineer, responsible for the tunnel design of many hydro-power tunnels in Vietnam. He also has been working in London, United Kingdom as senior geotechnical engineer before joining SINTEF, Norway in 2008. At SINTEF, he is working as a researcher and responsible for various tasks including tunnel mapping, rock mass quality evaluation, rock support, numerical modelling, etc. While working with SINTEF, he is also an Associated Professor in NTNU giving lectures in Numerical Modelling in Rock Engineering.

The seminar was well attended with participants from NTU and various industrial partners, including Building and Construction Authority (BCA), Defence Science and Technology Agency (DSTA), HBC Consultants, Housing and Development Board (HDB), Kiso-Jiban Singapore Pte Ltd, Land Transport Authority (LTA), Maritime and Port Authority of Singapore (MPA), Penta-Ocean Construction Co., Ltd, PR Consultants Offshore and Surbana International Consultants Pte Ltd

The Seminar ended with NTU-JTC I3C’s Co-Director, Dr Lu Ming presenting a token of appreciation to Dr Holmøy and Dr Trinh.