This paper presents a new design numerical tool for geosynthetic-reinforced soil embankments, used to mitigate rockfall risk in scenarios of large volumes, energies, and multiple block failures. The model can simulate both local block penetration into the uphill embankment face and extrusion mechanism frequently affecting the downhill face. The new model is based on an existing elastic-visco-plastic model, originally developed to simulate impacts of blocks on homogeneous granular strata. The model has been enhanced and modified by incorporating a plastic mechanism, accounting for the extrusion process potentially occurring within the embankment body. The model is initially described and then validated using available in situ real-scale test data; finally, the results of a parametric study, examining the influence of the main controlling parameters and the applicability of the tool for pre-design purposes, are illustrated.

Studying the shear rheological properties of clay is crucial for evaluating slope stability and preventing excessive displacement of roadbeds and retaining walls. In this study, a series of direct simple shear tests were conducted by a novel apparatus to investigate the shear rheological behavior of clay in western China. Test results reveal that both the shear strain-time curve and shear stress-strain curve can be well described by power functions, and the power of shear strain-time curve is independent of the shear stress level. Based on this finding, an empirical shear rheological equation under constant shear stress is built. By assuming the shear stress-strain curves as a series of parallel lines in a double logarithmic coordinate axis, shear equivalent timelines are proposed based on Yin Graham's equivalent timeline theory. The shear equivalent time is then introduced into the proposed empirical shear rheological equation, thereby an equivalent timeline shear rheological model considering the effect of consolidation pressure under varying shear stresses is derived. The shear rheological strains predicted by the model are shown to agree well with test data before clay failure.

Soil conditioning is crucial in maintaining stability during earth pressure balance (EPB) shield tunneling. Understanding the properties of the soil conditioner and its impact on soil is essential for ensuring the safety of the tunneling. This study focuses on investigating the penetration behavior of foam, a commonly used soil conditioner, in saturated sand. Experiments were conducted using a sand column device to simulate the foam penetration process in different sand beds. The experimental results reveal that foam penetration in the sand forms two linear pore pressure drop regions with different gradients, with the foam penetration area occupying the majority of the pore pressure. The foam penetration also introduces a flow velocity reduction in the sand column, resulting in blocking. Furthermore, a notable correlation emerged between the foam penetration velocity and the hydraulic gradient, akin to Darcy's law but with a different expression equation. The findings contribute to enhancing our understanding of soil conditioning in EPB shield tunneling and support the design of safer and more efficient tunneling processes.

Debris flows are a dynamic and hazardous geological phenomenon, as by definition, debris flows are rapid, gravity-driven flows of saturated materials that often contain a mixture of water, rock, soil, and organic matter. They are highly destructive and occur in steep channels, posing a significant threat to infrastructure and human life. The dynamics of debris flows are complex due to their non-Newtonian behaviour and varying sediment-water interactions, making accurate modelling essential for risk mitigation and emergency planning. This paper reports and discusses the results of numerical simulations of back analyses aimed at studying the reconstruction of a real rapid debris flow. The selected test case is the event that occurred on 12 and 16 March 2021 along the Rio Sonno channel, a tributary of the Liri River, following the landslide event of Rendinara (Municipality of Morino, Abruzzo Region, Italy). There are significant flow sources in the area, fed by a highly fractured carbonaceous aquifer that extends immediately upslope of the detachment zone. The continuous flow influences the saturation level in the fine-grained sediments and favours the triggering of the debris flow. This phenomenon was simulated using the commercial RAMMS code, and the rheological model selected was Voellmy fluid friction. The modelling approaches used in this research are valid tools to estimate the volumes of materials involved in the flow-feeding process and for the purpose of possible mitigation works (debris flow-type dams, weirs, flow diversion, etc.).

Rheological models capture the behaviour of soil structures and effectively evaluate the response of various transport corridors. These models represent the elastic and plastic behaviour of a structure. This paper reviews several rheological models that incorporate elasticity, viscosity, and plasticity principles. The review encompasses various rheological models developed as viscoelastic, elastoplastic, viscoplastic, elastoviscoplastic and viscoelastoplastic models, specifically for a better understanding of high-speed rail dynamics. Analytical solutions for these models are elaborated, focusing on the behaviour of soil structures and the interaction of layers, particularly in scenarios involving two or more layers. Additionally, detailed discussions cover the results and interpretations of various studies on these rheological models.

Railway transportation is widely recognized as an environment-friendly and sustainable means for conveying freight and passengers over long distances. This article investigates the effectiveness of utilizing scrap tire rubber granules and geosynthetics to enhance track performance in response to the growing demands for railway transport and the consequent escalation of train-induced loading. A multi-faceted methodology, incorporating experimental, numerical, and analytical techniques, is employed to examine the efficacy of these sustainable approaches. Results from three-dimensional (3D) finite element (FE) analyses conducted on slab tracks for high-speed railways reveal that the addition of a resilient layer, comprising scrap tire rubber granules, reduces vertical stress within the track substructure. Laboratory investigations on an innovative composite material consisting of soil, scrap rubber granules, and polyurethane demonstrate its potential to enhance track performance. Findings from two-dimensional (2D) FE analyses conducted on pile-supported railway embankments highlight an enhanced transfer of load to the pile head following the installation of a geogrid layer at the embankment base. Finally, the results from the analytical approach indicate a reduction in track settlement and a decrease in the track geometry degradation rate on reinforcing the ballast layer with 3D cellular geoinclusion. The novelty of this study lies in the comprehensive assessment of the innovative composite material under drained and cyclic loading conditions, the investigation of the influence of train loading on geosynthetic tension and the load transfer mechanism in railway embankments, and the development of an innovative computational methodology capable of assessing the effectiveness of 3D cellular inclusions in improving the ballasted railway track performance. The findings from this article underscore the effectiveness of these sustainable approaches in mitigating the challenges posed by increased loads on railway tracks, providing valuable insights for the ongoing efforts to optimize railway transportation infrastructure.