Advanced numerical analysis of landslide debris mobility and barrier interaction

ABSTRACT

Mitigation of natural terrain hazards through the use of flexible and rigid barriers has become a common type of geotechnical work in Hong Kong. The current design approach for these structural countermeasures typically involves separate debris mobility modelling and structural analyses of barriers subject to pseudo-static impact loadings. This practical approach, however, could not realistically account for the dynamic debris–barrier interaction. With a view to better capturing the response of barriers under the debris impact, effort has recently been devoted to developing an advanced numerical technique to model debris flows, barrier structural responses and the impact dynamics in a coupled manner. This paper presents some recent advances made in establishing the numerical technique of coupled analysis using a three-dimensional finite-element computer code LS-DYNA. The methodologies of modelling the landslide debris mobility, the large-deformation non-linear behaviour of a flexible barrier under impact and the coupled analysis of debris–barrier interaction are introduced. Back analyses of selected landslide events and debris impact tests of flexible barriers for verification of the computer models are discussed. The coupled analysis enables detailed investigation of the energy balance involved in the impact process. Preliminary results of this energy analysis are also presented.

KEYWORDS:

• Debris mobility
• flexible barriers
• debris–barrier interaction
• energy balance
• LS-DYNA
• finite-element modelling

Acknowledgements

This paper is published with the permission of the Head of the Geotechnical Engineering Office and the Director of Civil Engineering and Development, the HKSAR Government.

Additional information

Notes on contributors

Arthur K C Cheung

Mr Arthur K C Cheung obtained his BSc degree in Earth Sciences in 2011 and his MSc degree in Geotechnical Engineering in 2016, both from The University of Hong Kong. He is a Chartered Geologist with experiences in the fields of engineering geology and geotechnical engineering, with expertise in natural terrain hazards studies and 3D numerical modelling. He has more than six years of geotechnical and geological design experiences on a wide variety of projects in Hong Kong, the Mainland China, South Korea, Thailand, Vietnam and Nepal. He is the winner of the Glossop Award from the Geological Society of London in 2013. He is the author of the paper 3D Numerical Analysis and Design of Flexible and Rigid Barriers in the HKIE Geotechnical Division 37th Annual Seminar.

Jack Yiu

Ir Jack Yiu is an Associate in Ove Arup & Partners Hong Kong Limited. His genuine interest and strong technical background in geotechnical engineering have led to his involvement in a wide variety of significant infrastructure projects, such as the 2012 London Olympics, Singapore MRT Downtown Line, the Hong Kong Express Rail Link and the Brunei-Temburong Bridge. His particular expertise is in deep excavation and numerical methods for geotechnical design, which has led him to be the leading geotechnical engineer for a number of recent Hong Kong MTR consultancy packages. Ir Yiu has recently developed his new expertise in natural terrain/ slope hazard mitigation measures and the associated advanced dynamic analysis. He was the Project Manager of the pilot numerical investigation in landslide debris–flexible barrier structure interaction for the Geotechnical Engineering Office (GEO), Civil Engineering and Development Department (CEDD), the HKSAR Government.

Harris W K Lam

Ir Harris W K Lam is a Senior Geotechnical Engineer in the GEO, CEDD, the HKSAR Government. He has been working for the government for 17 years in the areas of slope stabilisation, natural terrain hazard mitigation, landslide investigation, slope maintenance and emergency repairs, etc. He is now managing a team of staff in GEO, focusing on the research and technical development on natural terrain hazard mitigation measures in Hong Kong.

Eric H Y Sze

Ir Dr Eric H Y Sze obtained his Ph.D. in Geotechnical Engineering from The University of Hong Kong. He is currently a Geotechnical Engineer in the GEO, CEDD, the HKSAR Government. His research interest is on soil dynamics, liquefaction and numerical modelling of impact problems. He has been a designer for flexible debris-resisting barriers and is now responsible for the research and development work for natural terrain hazard mitigation measures in Hong Kong.