Based in Wellington, New Zealand
UC (part-time & remote): PhD Student – Earthquake Engineering
Work (part-time): Geotechnical Engineer at Tonkin & Taylor Ltd (Wellington Office)
Research Title: “Using a Lateral Restraint to Mitigate Lateral Spreading: A Numerical Study”
Main supervisor: Chris McGann
Co-supervisor: Misko Cubrinovski.
Abstract: Post-earthquake observations have shown liquefaction-induced lateral spreading can have damaging impacts on the built environment. The ground movement can be particularly severe near an unsupported edge (e.g., riverbank or reclamation edge). Insufficient tolerance for this ground displacement results in damage. This is a well-known issue for new and existing developments in seismically active areas. Approaching this problem could include: 1) avoid land with potential for lateral spreading, 2) design / strengthen structures to tolerate lateral spreading, 3) larger scale ground improvement to mitigate liquefaction, or 4) targeted ground improvement purposed to mitigate lateral spreading directly.
Compared to the first three options, option 4 can be more practical and cost-effective given its more directed purpose and localised implementation. Option 4 aims to protect vulnerable structures with an underground barrier of ground improvement along the side(s) exposed to lateral spreading. This barrier acts as a lateral restraint, expected to reduce ground displacements to a tolerable magnitude. Significant reliance is placed on this solution’s ability to provide additional reinforcement to the unstable ground. Accordingly, it is crucial to have rigorous insight into its performance to inform its efficacy and design.
Lateral spreading and its mitigation involves complex behaviours and interactions. Assessment of this is often limited to the use of simplified methods that are unable to fully capture the dynamic and nonlinear intricacies of this problem. Advanced methods tend to be reserved for more critical projects, a single solution at a particular site, or later design stages. This could result in a potentially valid option being discounted (or vice versa) during the pivotal optioneering stage of an engineering project.
This study utilises 2D, fully-coupled, dynamic, effective stress analysis to investigate lateral spreading (the problem) and its mitigation using a lateral restraint (a possible solution). Parametric studies are carried out to explore the key engineering parameters, trends and mechanisms involved. This study focuses on the performance and effectiveness of a solution comprising piles (i.e., reinforcing elements) in a single-row configuration. Outcomes of the numerical study are compared against that of simplified approaches. Acquired insights are purposed to produce guidance / tools that support practitioners in the assessment and development of a lateral restraint mitigation solution. This research intends to enhance understanding of this complex engineering problem, supplement simplified approaches, and ultimately underpin a better-informed project optioneering stage exploring lateral spreading mitigation solutions.
Research interests: Earthquake engineering, soil liquefaction, liquefaction-induced lateral spreading and its mitigation, soil-structure interaction, numerical modelling.
Academic History: BEng (Civil Engineering) from University of Pretoria, South Africa.
Publications:
Rolfe, A., Chin, E. and Palmer, S., 2020. Design scenarios for piles in ground subject to liquefaction. NZSEE Conference. https://repo.nzsee.org.nz/handle/nzsee/1703
Rolfe, A. and Palmer, S., 2023. Mitigation of liquefaction-induced lateral spread ground displacements using an in-ground pile wall. NZSEE Conference. https://repo.nzsee.org.nz/handle/nzsee/2598
