Effects of near-surface environmental conditions on instability of an unsaturated soil slope

Blatz, James; Ferreira, Nelson John; Graham, J.

doi:10.1139/t04-058

Cited by 39 publications

(23 citation statements)

References 14 publications

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“…Early attempts to incorporate the effect of soil-atmosphere interaction in numerical analysis were focused mainly on adopting a summer and a winter undrained shear strength profile for London clay (Vaughan 1994) or summer and winter pwp profiles (e.g., Russell et al 2000;Kovacevic et al 2001;Nyambayo et al 2004;O'Brien et al 2004; Lees et al 2013). An alternative approach employed in the literature (e.g., Krahn et al 1989;Tsaparas et al 2002;Blatz et al 2004;Rouainia et al 2009;Rahardjo et al 2012) consists of running two independent analyses: one for the calculation of pwps from meteorological, vegetation, and permeability data and one for the calculation of slope stability from the obtained pwps. Although the latter approach has the advantage that pwps are calculated rather than prescribed, and as such the corresponding flow rates are consistent with the infiltration and evapotranspiration rates, this is a noncoupled approach.…”

Section: Introductionmentioning

confidence: 99%

Numerical study of the effect of soil–atmosphere interaction on the stability and serviceability of cut slopes in London clay

2017

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Abstract:The stability of cut slopes is greatly influenced by seasonal pore-water pressure variations under the combined effect of rainfall and vegetation. However, predicting soil-atmosphere interaction is not straightforward, due to the complexity of both the boundary conditions involved and the hydromechanical behaviour of soils, which is coupled and highly nonlinear, rendering the use of numerical tools, such as finite element analysis, necessary. This paper discusses the numerical modelling of soil-atmosphere interaction and presents the analysis of a slope cut in London clay in a highly vegetated area. The whole life cycle of the slope is considered with phases of low and high water demand vegetation and vegetation clearance. The analysis results indicate that dense vegetation is associated with high factors of safety, but may induce large differential displacements, which are likely to affect the serviceability of the slope. Vegetation clearance, however, may initiate instability, highlighting the need for effective vegetation management to achieve a balance between serviceability and ultimate limit states. Although the case considered is representative of southeast England, it introduces the necessary tools for realistic numerical analysis of soil-atmosphere interaction.Key words: slope stability, serviceability, vegetation, precipitation, soil-atmosphere interaction.Résumé : La stabilité des pentes entaillées est fortement influencée par les variations de pression de l'eau interstitielle saisonnières sous l'effet combiné des précipitations et de la végétation. Cependant, prédire l'interaction sol-atmosphère n'est pas si simple, en raison de la complexité des deux conditions aux limites en cause et le comportement hydromécanique des sols, qui est couplé et fortement non linéaire, ce qui rend l'utilisation d'outils numériques, tels que l'analyse des éléments finis néces-saire. Cet article traite la modélisation numérique de l'interaction sol-atmosphère et présente l'analyse d'une pente entaillée dans l'argile de Londres dans une zone très végétalisée. L'ensemble du cycle de vie de la pente est considéré avec des phases de demande en eau basse et haute de la végétation et la clairance de la végétation. Les résultats de l'analyse indiquent que la végétation dense est associée à des facteurs élevés de sécurité, mais peut induire des déplacements différentiels qui sont susceptibles d'affecter l'état de fonctionnement de la pente. L'enlèvement de la végétation, cependant, peut déclencher l'instabilité, soulignant la nécessité d'une gestion efficace de la végétation afin de parvenir à un équilibre entre la fonctionnalité et les états limites ultimes. Bien que le cas considéré est représentatif du Sud est de l'Angleterre, il présente les outils nécessaires à l'analyse numérique réaliste de l'interaction sol-atmosphère. [Traduit par la Rédaction] Mots-clés : stabilité des pentes, facilité d'entretien, végétation, précipitations, interaction sol-atmosphère.

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Section: Introductionmentioning

confidence: 99%

Numerical study of the effect of soil–atmosphere interaction on the stability and serviceability of cut slopes in London clay

2017

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“…The advantage of a numerical analysis is that it can incorporate more sophisticated and advanced models of soil hydraulic properties Rahardjo, 1997a, 1997b). Numerous numerical studies (Blatz et al, 2004;Gasmo et al, 2000;Ng and Shi, 1998a Chen and Zhang (2006) and Zhang and Chen (2006); Flow3D (Gerscovich, 1994); and FEMWATER (Lin et al, 1997), as in Ng et al (2001). Of particular concern is that, when an interface between two porous media is present, preferential infiltration may take place along the interface Zhang and Chen, 2006).…”

Section: Analytical and Numerical Solutionsmentioning

confidence: 99%

“…Although numerous field investigations (Blatz et al, 2004;Cui et al, 2005Cui et al, , 2010Gasmo et al, 1999;Kim and Lee, 2010;Li et al, 2005;Li et al, 2011;Lim et al, 1996;Ng et al, 2003;Rahardjo et al, 2005;Tsaparas et al, 2003;Tu et al, 2009;Zhan et al, 2007;Zhang et al, 2000) and laboratory model tests (Huang et al, 2008;Huat et al, 2006;Li et al, 2009b;Moriwaki et al, 2004;Take et al, 2004;Tohari et al, 2007) have been conducted on soil moisture responses to rainfall, comparisons of measured and calculated pore water pressure profiles (Trandafir et al, 2008) and changes in pore water pressure with time (Alonso et al, 2003;Huat et al, 2006;Lan et al, 2003;Sako et al, 2006) are still limited. It is very difficult to find a unique set of soil hydraulic parameters that could match all transient pore water pressure responses (Trandafir et al, 2008).…”

Section: Analytical and Numerical Solutionsmentioning

confidence: 99%

“…Other adopted computer programs for slope stability analysis include STABL (Chen et al, 2009) and SVSlope (SoilVision System Ltd, 2010). Various methods of slices were chosen to calculate the safety factor of the slope, for example Bishop's simplified method with circular slip surfaces (Ng and Shi, 1998b;Rahardjo et al, 2001Rahardjo et al, , 2007Tsaparas et al, 2002), Morgenstern and Price's method (Blatz et al, 2004;Cascini et al, 2010), and Janbu's method with non-circular slip surfaces (Wilkinson et al, 2002). The extended Mohr-Coulomb failure criterion (Fredlund et al, 1978) is usually adopted.…”

Section: Geotechnical Engineering Volume 164 Issue Ge5mentioning

confidence: 99%

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Stability analysis of rainfall-induced slope failure: a review

Zhang

et al. 2011

Proceedings of the Institution of Civil Engineers - Geotechnica

240

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Rainfall is one of the most significant triggering factors for slope failures in many regions around the world.Numerous research studies have been conducted to investigate infiltration of rainwater into a slope, and the effect of water infiltration on slope stability. In this paper, a review of existing research on infiltration analysis and slope stability analysis under rainfall infiltration is presented. Studies on infiltration analysis with conceptual models, analytical analysis and numerical modelling are first reviewed. The typical pore water pressure profiles in the slope are then discussed. Subsequently, recent developments in analyses of slope instabilities under rainfall conditions using the limit equilibrium method and coupled hydro-mechanical modelling are summarised, and major findings on critical hydrological factors related to rainfall-induced landslides are summarised and discussed. Finally, several research topics are suggested for further study.

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“…Thus, researchers have not been in a position to accurately predict landslide occurrence and plan response strategies for events such as typhoons and the heavy rains where the effects of rainfall infiltration on landslide activity are not negligible. Consequently, integrating rainfall infiltration and groundwater seepage into slope stability models has become a focus of natural hazard mitigation efforts in recent years (Bozzano et al 2002;Blatz et al 2004;Cascini et al 2006;Guzzetti et al 2008).…”

Section: Introductionmentioning

confidence: 99%

Local rainfall thresholds for forecasting landslide occurrence: Taipingshan landslide triggered by Typhoon Saola

2016

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This paper presents a case study of the Taipingshan landslide, which was triggered by Typhoon Saola in 2012. Taipingshan villa is one of the most famous scenic locations within the Taipingshan National Forest Recreation Area in northern Taiwan. Since the early 1990s, evidence of recent landslide activity appeared throughout the Taipingshan villa and included features such as tension cracks, ground settlement, and cracking in manmade structures. In response, a series of geological investigations and in-site/laboratory tests were conducted in 2010 to estimate slope stability and predict critical rainfall thresholds (event accumulated rainfall) for landslide activity. Results revealed that the critical rainfall threshold for the Taipingshan National Forest Recreation Area is 1765 mm. In 2012, that threshold was tested when Typhoon Saola brought tremendous rainfall to northern and eastern Taiwan and triggered activity along the main scarp of sliding mass B located near the History Exhibition Hall. According to in situ extensometer readings and on-site precipitation data, the extensometer was severed at an accumulated rainfall 1694 mm. Field monitoring data during the typhoon event are in good agreement with the rainfall threshold. These preliminary results suggest that the threshold may be useful for assessing the rainfall threshold of other landslides and a good reference for establishing early warning systems for landslides.

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Effects of near-surface environmental conditions on instability of an unsaturated soil slope

Cited by 39 publications

References 14 publications

Numerical study of the effect of soil–atmosphere interaction on the stability and serviceability of cut slopes in London clay

Numerical study of the effect of soil–atmosphere interaction on the stability and serviceability of cut slopes in London clay

Stability analysis of rainfall-induced slope failure: a review

Local rainfall thresholds for forecasting landslide occurrence: Taipingshan landslide triggered by Typhoon Saola

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