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Towards Submarine Landslides and Their Consequences

Periodic Reporting for period 1 - ToSubC (Towards Submarine Landslides and Their Consequences)

Reporting period: 2017-08-01 to 2019-07-31

The overall objective of this project aims to develop a robust numerical computational framework and a reliable constitutive model for predicting potential submarine landslides and for evaluating their threat including both of their direct threat to subsea pipelines and their indirect threat to coastal communities via generating a tsunami. The prediction of submarine landslides and their consequences are of great importance owing to the continuing gross of human activities at offshore areas. Efforts have been devoted in this project to address the problems related to the coupling simulation of the seawater, the submarine sediments and the subsea infrastructure (e.g. pipelines). Such a coupled simulation is a formidable challenge in modelling submarine landslide processes owing to the variety in the corresponding finite element formulations. Additionally, this project also focuses on the constitutive model for submarine sediments which behave like a solid at the stage of triggering and final deposition but like a fluid while sliding. This complex feature calls for a robust constitutive model capable of representing both of its solid-like and fluid-like behaviors.
(1) An elastoviscoplastic model that can describing both the solid-like and fluid-like behavior of clays has been implemented into the framework of the particle finite element method which is then used for studying the retrogressive failure behavior of sensitive clays in landslides.
Relevant exploitation and dissemination:
- A journal article named “Dynamic modelling of retrogressive landslides with emphasis on the role of clay sensitivity” has been formed based on this research work and submitted to “International Journal for Numerical and Analytical Methods in Goemechanics” (under review).
- A conference paper named “Particle finite element modelling of retrogressive slope failure in sensitive clays” has been formed based on this work.
- A presentation has been given at the 15th International Conference of the International Association for Computer Methods and Advances in Geomechanics held in Wuhan, China, Oct 2017.
- Dr Xue Zhang has been awarded the prestigious “John Carter Award” at this international conference.
(2) A three-dimensional version of the particle finite element method has been developed with the implementation of Non-Newtonian fluids in collaboration with Dr Alessandro Franci, which enables the approach to consider 3D problems. A paper titled “3D numerical simulation of free-surface Bingham fluids interacting with structures using the PFEM” has been formed and submitted to an international journal “Journal of Non-Newtonian Fluid Mechanics” (under review).
(3) The finite element formulation for solid mechanics and fluid dynamics has been unified on the basis of a general mixed variational principle. The proposed formulation enables the fluid-solid coupling to be achieved in a monolithic manner. With implementing the formulation into the particle finite element method, the resulting approach is now able to simulate submarine landslides and their consequences. This work forms an article titled “A unified solid/fluid finite element formulation and its possibility for modelling submarine landslides and their consequences” which is now under review by the international journal “Computer Methods in Applied Mechanics and Engineering”
(4) Knowledge transfers have been conducted via giving a seminar at CIMNE.
(5) Dr Zhang attended the XIV International Conference on Computational Plasticity: Fundamentals and Applications (COMPLAS 2017) held by the host institution (CIMNE).
(6) Dr Zhang visited the University of Liverpool for disseminating his work related to the modelling of submarine landslides and their consequences and sought collaborations.
(7) Collaboration between Dr Xue Zhang and researchers from University of Bologna, Italy has been built up on the modelling of earthquake-induced landslides using the particle finite element method.
The developed simulation approach is an algorithm beyond the state of the art. The proposed approach recasts the governing equations for different nonlinear problems into a unified formulation that thus can be resolved using a single modern solution engine. The resulting numerical modelling package is capable of predicting potential submarine landslides and estimating their consequences in a single simulation which is of great importance for the analysis of submarine slope stability and the relevant risk evaluation of its threat to offshore infrastructure, such as gas/oil platform, subsea pipelines and cables, and to coastal communities via generating tsunamis.