Numerical modelling of slope–vegetation–atmosphere interaction: an overview

The behaviour of natural and artificial slopes is controlled by their thermo-hydro-mechanical conditions and by soil–vegetation–atmosphere interaction. Porewater pressure changes within a slope related to variable meteorological settings have been shown to be able to induce soil erosion, shrinkage–swelling and cracking, thus leading to an overall decrease of the available soil strength with depth and, ultimately, to a progressive slope collapse. In terms of numerical modelling, the stability analysis of partially saturated slopes is a complex problem and a wide range of approaches from simple limit equilibrium solutions to advanced numerical analyses have been proposed in the literature. The more advanced approaches, although more rigorous, require input data such as the soil water retention curve and the hydraulic conductivity function, which are difficult to obtain in some cases. The quantification of the effects of future climate scenarios represents an additional challenge in forecasting slope–atmosphere interaction processes. This paper presents a review of real and ideal case histories regarding the numerical analysis of natural and artificial slopes subjected to different types of climatic perturbations. The limits and benefits of the different numerical approaches adopted are discussed and some general modelling recommendations are addressed

Triaxial stress path tests on artificially prepared analogue alpine permafrost soil

Some degrading rock glaciers have been exhibiting deepening depressions, accelerating strain rates and, in some rare cases, sudden release of mass movements. Warming permafrost already mobilises lower strength as temperatures rise, however unusual stress paths with lateral stresses greater than vertical stresses, instead of vice versa, could exacerbate this with lower strength at failure, and hence higher vulnerability. This paper investigates the mechanical behaviour of artificially frozen soil specimens at temperatures between -3.0 and -0.3°C under various stress paths, axial (A) and lateral (L), compression (C) and extension (E), for total stress paths AC, AE, LE, LC. Acoustic emissions were detected during shearing in order to expose how the deformation mechanisms develop from a microstructural point of view. Deviatoric stress mobilised in the stress path tests was linearly dependent on the temperature (within the ranges tested): a temperature increase resulted in a decrease in residual deviatoric stress. Comparison between the residual deviatoric stresses obtained from the different stress path tests indicates that 1) values mobilised with radial stress greater than axial stress were lower than vice versa, 2) more strength was mobilised when changing lateral stress paths than axial, with 3) the lowest strength mobilised in AE beneath a depression.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

A novel technique to monitor the subsurface movements of landslides

Slope Deformation Sensors SDS) were developed to monitor profiles of soil deformation at a high frequency during slope monitoring and landslide triggering experiments. It was hypothesised that the surface and subsurface movements could be combined to integrate the temporal development of the movements, and help to monitor the initiation and propagation of the shear bands indirectly, as well as to predict the volume of the eventual landslide. Four SDSs were installed in a 38ยบ slope in Northern Switzerland and slope movements due to two artificial rainfall sprinkling experiments in October 2008 and March 2009 were monitored. This paper describes the design, numerical validation, installation details and performance of the SDSs during the first rainfall event. The data acquired from SDS in terms of bending strain, deformation profiles, and an indication of the mechanical energy transmitted from the surrounding soil, are analysed and compared to the patterns of surface movements of the slope and changes in the horizontal earth pressure. The findings are interpreted based on the applied rainfall, hydrological properties of the slope, bedrock shape and the specifications of the observed failure surface in the following Landslide Triggering Experiment. Details of the data acquired from SDSs during the second experiment in March 2009 are reported and analysed in a second paper.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author