Characterisation of climatic variables used to identify instability thresholds in clay slopes

Abstract

The paper reports the results of a slope-atmosphere interaction analysis performed with reference to geo-hydro-mechanical conditions typically observed on the Southern Apennines (Italy). The aim of the analysis is to gain some understanding in the characterisation of climatic variables employed to identify instability thresholds in clay slopes. A seepage analysis was undertaken first, showing that Mediterranean climates can produce significant pore-pressure changes also at depths not usually considered to be affected by atmospheric conditions. Based on the results of the seepage analysis, limit equilibrium analyses were carried out for a 5 m and a 20 m deep landslide, confirming that also deep movements in clay slopes can be related to slope-atmosphere interaction. The characterisation of climatic variables aimed at identifying instability thresholds is finally discussed based on the analyses reported in the paper. The results show that net rainfall cumulated over 2 and 6 months represent suitable climatic variables for the 5 m and the 20 m deep landslide, respectively. These findings suggest that the stability of a clay slope, when referred to shallow movements, is likely to depend on the rainfall infiltrating over a few weeks at least. When deep movements are considered, the stability seems to depend more on the rainfall gradually infiltrating during the most rainy seasons.

Coupled hydro-mechanical modelling of soil–vegetation–atmosphere interaction in natural clay slopes

“…Figure 2 for piezometer locations) still show some seasonal changes, but their average magnitude agrees very well with the values predicted (Figure 14c). These results confirm findings by Pedone et al (2018) with reference to a uniform clay slope, in that significant pore pressure fluctuations at large depths can probably occur only if highly permeable inclusions are interbedded within the clays, which were not considered in the current numerical model.…”

“…Nonetheless, recent findings indicate that, in clay slopes, climate can induce pore pressure variations and associated slope movements also at intermediate (10-30 m) to large (30-100 m) depths (e.g. Tommasi et al 2013;Vassallo et al 2015;Cotecchia et al 2014;2016;Lollino et al 2016;Pedone et al 2018).…”

Modelling seasonal landslide motion: Does it only depend on fluctuations in normal effective stress?

“…Rainfall is a primary factor in the modification of the hydro-mechanical regime within the ground and the mobilization of landslides, for example, 1,2 In the last decades, the risks posed by landslides have been aggravated by the emergence of alterations in global climate, with recent projections suggesting that an increase in the frequency and magnitude of landslides can be expected in several regions of the world, with obvious detrimental consequences for infrastructure and communities. 3 These concerns apply to landslides of all kinds, from translational earth slides involving shallow deposits (e.g., [4][5][6] ) to deeper deformation mechanisms typical of clay-rich formations (e.g., [7][8][9] . )…”

Effect of Various Rainfall Conditions on the Roadside Stabilisation of Slopes in Gippsland

“…A parametric study was conducted [17] to investigate the effect of rainfall intensity, soil properties, and the position of the groundwater table on slope stability. Another study [18] investigated the threshold of the instability of a clay soil slope located in the Mediterranean area induced by climatic variables, including rainfall, average temperature, and evapotranspiration. Moreover, researchers [19] have studied the effect of extreme storms on typical railway embankment stability by numerical simulations and investigated the effect of soil hydraulic characteristics under rainfall conditions.…”