Research

Wider research context/theoretical framework: Bedding landslides are widely distributed in sediments with inclined structures. They may undergo catastrophic failure, posing considerable threats to society. The localized deformation at the interface between the sliding mass and the bedrock of bedding landslides normally accounted for the majority of sliding movement. Thus, the mobilization of such slides is intimately related to the mechanical behaviour of the interface at the basal shear zone. As a result, a comprehensive investigation on soil-rock interface in bedding landslides are necessary to improve our understanding of the origin of catastrophic failure and to help develop robust numerical models for predicting bedding landslides and similar geohazards. Hypotheses/research questions/objectives: In this project, we will explore the mechanical behaviour of soil-rock interface by employing laboratory experiments and advancing a numerical model to simulate the failure process of bedding landslides along soil-rock interfaces. Approach/methods: This proposal combines innovative experiments and numerical simulations. A well-document bedding landslide occurred in the Three Gorges Reservoir area in China will be chosen to study the mechanical behaviour of soil-rock interfaces. Laboratory tests will be conducted for studying the shearing behaviour of shear-zone soil and soil-rock interface from elementary to model scale; An advanced hypoplastic model will be proposed considering the stress history of soil and the surface properties of the interface; A numerical model with the advanced constitutive model will be developed to mimic the post-failure process of the bedding landslide. Level of originality/innovation: A comprehensive experimental investigation on the shearing behaviour of soil-rock interfaces for bedding landslides is the first time in the discipline of engineering geology; The proposed interface hypoplastic model is for the first time considering the surface properties. The SPFEM simulation with hypoplastic framework is novel for mimicking the post- failure of bedding landslides with soil-rock interfaces. Primary researchers involved: Xuan Kang, as a Ph.D. student at the China University of Geoscience Wuhan, is the PI for this project. Her research focused on landslide stability, in-situ and laboratory tests on landslide materials. During her Ph.D., she has published 4 peer-reviewed papers in high impact journals. Prof. Wei Wu, as the director of the Institute of Geological Engineering, is the mentor for this project. He has made pioneering contributions in the field of constitutive modelling and numerical simulation.

In this research project, a 3D grain-scale continuum-discontinuum hierarchical multiscale computational framework is proposed to improve the deep understanding of compaction banding formations in the sedimentary porous rocks that are of strong interest and of major challenge in the modern geomechanics. The proposed grain-scale continuum-discontinuum multiscale numerical framework for porous geological media consists of three levels including FEM meshes at macro-scale, DEM grains at meso-scale and hypoplastic peridynamic points at micro-scale. Furthermore, the region partitioning search algorithm and CPU-GPU heterogeneous computing architecture both contribute to improvement of computational efficiency to construct an open-source 3D computational platform that is suitable to simulate large-scale geological and geotechnical problems. To systematically investigate the localized failure mechanism of compaction bands in porous geological media at laboratory and field scales, one laboratory-scale and one field-scale numerical models are simulated by 3D computational platform. The influencing factors of boundary conditions, stress fields, geomaterials heterogeneity, nonlocal characteristic length, granular shapes, etc. on the localization failure processes of compaction bands will be summarized and analyzed. Sequentially, effects of microstructural mechanism including pore collapse, grain debonding, intra-granular damage and grain crushing on the nucleation and propagation of compaction bands during the localized failure processes. Furthermore, localized failure mechanism of the geological tectonic phenomena, i.e., coexistence of pure compaction bands and shear enhanced bands, will be numerical explored .

Within the scope of this proposal, “mountain geohazards” are understood as extremely rapid, gravitationally driven processes which typically occur in mountain areas and are potentially hazardous for society. Such processes are e.g. landslides in the very broad sense of the term, snow avalanches, glacial lake outburst floods, or process chains involving one or more of those phenomena. Mountain geohazards lead to significant losses of life, public infrastructure, and private property every year, all around the world. Disasters resulting from inadequate risk governance act against the SDGs 3, 9, and 11, among others. Whereas it is well established that societal change along with increased exposure has resulted in increasing losses and disasters, it is unclear to what extend and at what time-scale certain geohazard processes are affected by climate change. An increased understanding of all aspects of mountain geohazards now and in the future, from triggering to process dynamics and societal impact and perception, requires concerted inter- and transdisciplinary efforts and is necessary to inform risk governance and ultimately reduce losses. Austria is not only a country frequently affected by mountain geohazards, but also having developed a highly active scientific community and a powerful research infrastructure to investigate both the relevant physical processes and their socio-economic consequences. The proposed Cluster of Excellence aims at further strengthening and extending the available expertise and networks, in order to form an even stronger basis for risk governance efforts not only in Austria but also internationally, particularly in the Global South, and to strengthen the role of inter- and transdisciplinary Austrian mountain geohazards research as an international flagship.