Abstract
Sensitive clays are known for producing retrogressive landslides, also called spread or flowslides. The key characteristics associated with the occurrence of these landslides on a sensitive clay slope must be assessed, and the potential retrogressive distance must be evaluated. Common risk analysis methods include empirical methods for estimating the distance of potential retrogression, analytical limit equilibrium methods, numerical modelling methods using the strength reduction technique, and the integration of a progressive failure mechanism into numerical methods. Methods developed for zoning purposes in Norway and Quebec provide conservative results in most cases, even if they don’t cover the worst cases scenario. A flowslide can be partially analysed using analytical limit equilibrium methods and numerical methods having strength reduction factor tools. Numerical modelling of progressive failure mechanisms using numerical methods can define the critical parameters of spread-type landslides, such as critical unloading and the retrogression distance of the failure. Continuous improvements to the large-deformation numerical modeling approach allow its application to all types of sensitive clay landslides.
Highlights
Clays are constituted of fine-grained soil material having a grain size of less than approximately0.05 mm
An equilibrium must be satisfied in terms of total stress (σ), it being the sum of effective stress (σ0 ) and pore pressure (u)
Analytical methods are a way to achieve it. Those methods are based on the principle of limit equilibrium and they consider successive slices of soil of finite thickness and compute the forces and moments acting on each slice
Summary
Clays are constituted of fine-grained soil material having a grain size of less than approximately0.05 mm. Clays are constituted of fine-grained soil material having a grain size of less than approximately. A clay soil is cohesive with a plastic behaviour. The word clay can be used to indicate specific minerals, such as kaolinite or illite. We refer to clay as a fine-grained soil that is plastic, cohesive, and that may or may not contain clay minerals [1]. A soil is called sensitive if its sensitivity (St ) is greater than 1. The sensitivity is the ratio of the undisturbed soil strength to the remoulded shear strength (Equation (1)) [2]: St =
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