Research

1. Debris flow, mud flow & submarine landslide 

A comprehensive investigation of debris flow with the use of a coupled Computational Fluid Dynamics and Discrete Element Method (CFD–DEM) scheme is conducted with the consideration of free boundary of fluid. The major goal of this research is to develop an in-depth understanding of the grain-scale mechanisms that control the velocity and height profile of a debris flow under the influence of geometric and geologic parameters (e.g. viscosity, density, particle size distribution, slope angle, and base roughness). 

Collaborators:

• Dr Andy Leung, Hong Kong Polytechnic University 

• Prof. Yuri Dumaresq Sobral, Department of Mathematics at the University of Brasilia

• Ir. Ken Ho, Geotechnical Engineering Office at HK Government

• Dr. Johnny Cheuk, AECOM

2. Oil shale (Anisotropic rock)

This project aims to develop a new numerical approach to model inherently anisotropic rocks with the use of the Discrete Element Method (DEM). In the DEM model, the existence of inherently anisotropy will be explicitly represented by imposing individual smooth-joint (SJ) contacts into the bonded-particle model (BPM) with the same orientation. Uniaxial compression tests, Brazilian tests, biaxial tests and true triaxial tests will be performed to examine the effect of anisotropy angle on the mechanical behaviors including strength, deformation and failure pattern. The numerical model is validated by comparing the macro- and micro-scale behaviors with those obtained in laboratory. Future work is to apply the proposed model to study field-scale problems, e.g. borehole breakouts and hydraulic fracturing in shale formations.

Generation of inherently anisotropic models for tests under different stress conditions

Collaborators:

• Dr. Xiaodong Ma, Stanford University

• Dr. Matt Pierce, Itasca Consulting Group

3. Static liquefaction and instability in granular media

Static liquefaction of sands is a critical form of undrained and drained instability affecting granular materials. Many geotechnical failures such as instability of embankments, slopes and founds have been attributed to the liquefaction of cohesionless soil caused by sudden reduction of shear strength due to pore water pressure build up.  In spite of intensive research on this subject over the last 20 years, little has been known on the mechanisms triggering the liquefaction potential of loose sands. This project aims to demystify the micromechanics behind the phenomenon of static liquefaction using particulate DEM modeling. Virtual triaxial tests will be conducted in both drained and undrained condition, both with stress path leading to the instability zone. This will enable us to look at the evolution of fabric and soil skeleton throughout the instability processes. The outcome of the project will help understanding the static liquefaction phenomenon and enhance the existing constitutive models for failure prediction.

                                            Identifying the onset of instability in Constant Shear Drained (CSD) test with the  the second order work 

Collaborators:

• Dr. Catherine O'Suliivan, Imperial College London 

• Dr. Kevin Hanley, University of Edinburgh

4. Exploring critical state behaviour using DEM

This research explores the capacity of DEM to extend understanding of soil behaviour within the critical state soil mechanics framework. The effect of samples size, inter-particle friction, intermediate stress and rotation resistance is examined on the critical-state response of soil observed in DEM simulations. 

Influence of intermediate stress ratio (b) on the failure mode

Collaborators:

• Dr. Catherine O'Suliivan, Imperial College London 

• Dr. Kevin Hanley, University of Edinburgh

5. Embodied energy and embodied carbon in geotechnical engineering structures

Embodied energy (EE) of a construction project has been associated with carbon footprint as an indicator of sustainability. EE of different type of tunneling method and pipe-laying method was evaluated. By breaking down the analysis of EE consumption into three categories (materials, transportation, and installation), it reveals that materials dominate approximately 60% of the total EE. Tunnels and pipelines can be categorised as direct energy-intensive construction for which the transportation and installation can collectively account for as much as 40% of the total EE.

Detailed components breakdown of embodied energy for two types of tunnel of South Island Line

Collaborators:

Research Funds

1.  "Low-carbon Multi-functional Compressed Stabilized Earth Bricks made from Hong Kong Marine Deposits, Recycled Tire Rubber, and Waste Ash" 

   • Environment and Conservation Fund (ECF), 2024-256, HK$392,000, Principal Investigator, Jan 2026-  Jun 2027

2. "Multiscale study of particle size segregation in debris flow” 

   • General Research Fund (GRF), 17200724, $1,134,931, Principal Investigator, Jan 2025 - Jan 2028

3. "Using municipal solid waste incineration ash for low-carbon stabilization of dredged marine deposits"

   • Environment and Conservation Fund (ECF), 2023-156, HK$500,000, Principal Investigator, Jan 2025-  Jan 2027

4. "Low-carbon high-performance deep mixing piles for land reclamation"

   • Green Tech Fund (GTF), 202220024, HK$2,783,000, Principal investigator, Jul 2024 - Jun 2026

5. "Multiscale study of basal resistance for geophysical granular flows over complex topography "

   • General Research Fund (GRF), 17205222, $1,002,500, Principal investigator, Jan 2023 - Dec 2025

6.  "Feasibility study of using microbially induced calcite precipitation (MICP) stabilized dredged marine clay as fill materials for sustainable land reclamation in Hong Kong"

   • Environment and Conservation Fund (ECF), 2021-156, HK$500,000, Principal investigator, December 2022 - December 2024

7. "Towards a physics-based, multiscale paradigm for the modeling of debris flow entrainment"

   • General Research Fund (GRF), 17205821, $911,317, Principal investigator, Jan 2022 - Dec 2024

8. "Feasibility study of using dredged marine deposits stabilised with coal fly ash as fill materials for geotechnical projects in Hong Kong"

   • Environment and Conservation Fund (ECF), 2020-170, HK$490,000, Principal investigator, July 2021 - July 2023

9. "Sustainable reclamation in HK"

   • Eunsung Offshore Marine and Construction, HK$3,000,000 (with RGC matching), Principal investigator, Jan 2019 – Dec 2023 

10. "Study of cement stabilized soil for the sustainable reclamation of the third runway of the Hong Kong international airport"

    • HKAA, HK$ 461,949, Principal investigator, Jan 2018 – Dec 2019 

11. "Study on debris flow transport mechanisms based on coupled fluid-particle method"

• • State Key Laboratory of Geohazard Prevention and and Geoenvironment Protection, RMB 80,000, Principal investigator, Jan 2018 – Dec 2019 

12. "Recycling tyre waste as a useful geo-material to enhance sustainability"

• • Environment and Conservation Fund (ECF), Grant No. 2016-55, HK$ 1,127,600, Principal investigator, May 2017 – Nov 2019 

13. "Experimental and Numerical Investigation of Depositional Mechanism of Mountainside Debris Flows"

• • State Key Laboratory of Hydraulics and Mountain River Engineering, RMB 100,000, Principal investigator, Jan 2017 – Dec 2018 

14. "Numerical investigation of debris flow impact on debris-resisting barrier"

• • HKU Seed Funding Programme for Basic Research, Grant No. 104004120, HK$45,980, Principal investigator, April 2016 - April 2018

15. "Modelling of inherent anisotropy in sedimentary rocks" 

• • HKU Seed Funding Programme for Basic Research, Grant No. 104003446, HK$47,100, Principal investigator, June 2015 - June 2017

16. "Coupled Fluid-Particle Modeling for Debris Flows" 

• • General Research Fund (GRF), Grant No. 17203614 , HK$702,894, Principle investigator, Jan 2015 - Dec 2017

17. "Micromechanism research on deformation and fracture of rock mass considering time effect"

• • National Natural Science Foundation of China (NSFC) - Hong Kong and Macao and overseas scholars collaborative research fund project, Grant No. 51428902, RBM$200,000, Principle investigator, Jan 2015 - Dec 2016

18. "Micromechanical investigation of sandstone under true triaxial loading"

• • Institute of Rock and Soil Mechanics Chinese Academy of Sciences, Grant No. Z041004, RMB100,000, Principle investigator, Jan 2015 - Dec 2016

19. Departmental Strategic Development Fund 

• • HK$60,000, Principle investigator, Sept 2014 - Feb 2015

20. "Micromechanical investigation of time-dependent behaviour in rock mass" 

• • HKU Seed Funding Programme for Basic Research, Grant No. 201311159003, HK$83,800, Principal investigator, June 2014 - May 2016

21. "Time-Dependent Pile Capacity Behavior in Coarse-Grained Soils by A Coupled Discrete-Continuum Modelling Approach" 

• • Research Grants Council of Hong Kong - General Research Fund (GRF), Grant No. 122813, HK$645,500, Co-investigator, Jan 2014 - Dec 2016

22. "Carbon Footprint Assessment of Trenchless vs. Traditional Pipe Laying Approaches" 

• • Towngas contract research, HK$98,000, Principal investigator, Sept 2013 - Aug 2014

23. "Sustainability information modelling for project lifecycle environmental (SIMPLE) appraisal in construction" 

• • HKU's The Twenty-ninth RAP/PDF Scheme, HK$946,701, Co-investigator, April 2013 - March 2016

24. "Micromechanical investigation of undrained cyclic loading in sand" 

• • HKU Seed Funding Programme for Basic Research, Grant No. 201111159225, HK$102,000, Principal investigator, June 2012-April 2013

25. "The role of particle shape in creep"

• • HKU Seed Funding Programme for Basic Research for New Staff Grant No. 201101159008, HK$240,000, Principal investigator, June 2011-Feb 2013

Other Funds

• Engineering Overseas Visitor Program Fellowship, HKU, HK$50,000, Principal investigator, June-July 2012.

• Micro mechanics of cyclic soil response. William Mong Visiting Research Fellowship (to host Dr. Catherine O'Sullivan for visiting exchange to HKU), HKU, HK$25,000, Principal Investigator, February 2012.

• Engineering Overseas Visitor Program Fellowship, HKU, HK$46,500, Principal investigator, July-August 2011.