Research

This project focuses on the development and application of advanced numerical methods to investigate the formation and evolution of compaction bands in geomaterials. Specifically, hypoplastic constitutive modeling will be coupled with a phase-field approach to provide a robust and thermodynamically consistent framework for simulating strain localization phenomena. Compaction bands, which are localized zones of intense volumetric deformation, play a critical role in influencing the mechanical behavior and permeability of porous materials such as rocks and soils. Traditional numerical methods often struggle to capture their initiation and propagation due to mesh dependency and difficulties in tracking discontinuities. To address these challenges, the proposed study employs a phase-field formulation that regularizes discontinuities and enables the seamless simulation of evolving localization patterns.

Supershear earthquakes represent one of the most hazardous rupture modes because rupture velocities exceeding the shear-wave speed can strongly amplify ground motion through Mach-cone-like wave focusing. The uploaded paper develops a two-dimensional hybrid FEM/peridynamic framework to study the transition from sub-Rayleigh to supershear rupture in both dry and fluid-saturated media. In this framework, peridynamics is used to model solid deformation, damage, and rupture propagation, while FEM is used to solve pore-pressure diffusion and fluid flow in saturated porous media. The model is validated against Homalite impact experiments and PMMA frictional-interface experiments, and then applied to dry and saturated fault-like media. A key finding is that dry media may exhibit either direct supershear transition or the Burridge–Andrews mother–daughter crack mechanism, whereas fluid-saturated media favor direct supershear transition due to poroelastic effects near the rupture front. The study also shows that pore-pressure perturbations can accelerate rupture propagation and allow rupture speed to approach the fast compressional wave speed in saturated media. However, several important limitations remain. The current simulations treat rocks mainly as linear elastic materials and use a linear slip-weakening friction law. Natural fault zones, in contrast, involve plastic yielding, permanent damage, rate- and temperature-dependent friction, heterogeneous permeability, evolving pore pressure, and complex fault-zone geometry. These processes may strongly influence rupture acceleration, supershear transition, off-fault damage, and seismic energy radiation. The proposed project will therefore extend the existing FEM/PD framework toward a more realistic poro-elasto-plastic and thermo-hydro-mechanical model for dynamic earthquake rupture in mature fluid-saturated fault zones.

Rainfall-triggered landslides pose increasing risks in Europe and Asia, with granite residual soil (GRS) slopes particularly vulnerable due to their high sensitivity to water. However, the hydro-mechanical degradation mechanisms of GRS remain poorly understood, and there is a lack of low-carbon, eco-sustainable solutions to ensure both short- and long-term slope stability. This project aims to develop an eco-sustainable, synergistic reinforcement strategy for GRS slopes by integrating protein-based hydrogels with vegetation. The approach combines experimental investigations and advanced modelling to achieve this objective. On the experimental front, the project will evaluate how hydrogels enhance GRS stability while gradually degrading to facilitate seed germination, enabling a smooth transition from initial reinforcement to long-term, vegetation-based stabilisation. Planned activities include CT-coupled triaxial tests to capture microstructural evolution and strength changes, hydrogel–seed–soil compatibility trials, and large-scale slope model experiments. On the theoretical front, a novel root-growth phase-field model will be developed to simulate root development and hydro-mechanical coupling, rigorously calibrated against experimental results. Aligned with the MSCA Work Programme, this project will deliver scientific impact by advancing multiscale modelling of eco-friendly soil reinforcement, economic and technological impact by creating a cost-effective, patentable alternative to conventional slope stabilisation, and societal impact by mitigating landslide risks and supporting climate adaptation in vulnerable regions.