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  • Experimental and numerical moddelling of rainfallinduced slope instabilities in unsaturared sandy soil
    Josifovski, Josif ; Susinov, Bojan ; Tasevska, Magdalena
    The behaviour of natural or engineered slopes is controlled by the thermo-hydro-mechanical conditions and soil–atmosphere interaction. The consequences of the climate change regarding the slope ... stability are ever more present in different parts of the world. Therefore, most of the research on this topic nowadays is concentrated to determine the climate influence on the slope stability. They atmospheric perturbations are often manifested with short and intense rainfalls sometimes reaching even a value of monthly precipitation. The increasing rate, size and frequency of the slope instabilities in the past couple of years is becoming quite alarming, thus more decisive steps have to be made to define the risk. Among the atmospheric perturbations beside the sharp temperature change, hence the intense rainfall is considered as a key factor which directly relates to soil sliding or erosion. The rainfall water partially infiltrates in the soil, thus changes the porewater pressure within a slope leading to an overall decrease of the available soil strength and suction with depth and, ultimately, to a progressive slope collapse. This paper presents an analysis of ideal slope example subjected to heavy short duration rainfall. For this purpose, both physical and numerical model were employed. First, a small-scale physical model of unsaturated sandy slope was used to determine the rainfall infiltration rate into the slope and other hydraulic properties for which the slope was adequately instrumented with suction and water content sensors. The monitoring showed that the infiltrated water sharply increases the volumetric water content which generally reduces the strength and suction of the soil. In terms of numerical modelling, a coupled hydro-mechanical analysis was performed to simulate the slope-atmospheric interaction. For the hydraulic part a van Genuchten model was assumed which requires definition the soil water retention curve and hydraulic conductivity function obtain from the laboratory and experimental testing, while for the mechanical part two different soil models were used a standard with Mohr Coulomb criteria and Basic Barcelona as advanced able to describe the unsaturated nature of the soil. The two-dimensional finite element `stability has been evaluated for a slope inclination of 1:1 and 1:2. Moreover, different rainfall scenarios were examined with an objective to determine the influence of infiltration rate and duration of rainfall. It was proven that relatively short of few hours up to 12 hours rainfall with intensity of 10 to 30 mm/h have significant influence on the overall stability. The prediction of future climate scenarios and forecasting of slope–atmosphere interaction processes are a challenging task. Nevertheless, the study results re-assure that the presented approach and models are able to re-evaluate the reliability and stability of the existing natural and engineered slopes on measured precip
    Vir: Proceedings : 16th International simposium Water management & hydraulic engineering WMHE 2019, 5-7th September, Skopje, North Macedonia (Str. 466-477)
    Vrsta gradiva - prispevek na konferenci ; neleposlovje za odrasle
    Leto - 2019
    Jezik - angleški
    COBISS.SI-ID - 134458883

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