Quantification of mechanical strength and sliding stability of an artificial water catchment (Chicken Creek)

Baba, H. Ould, Peth, S., Horn, Rainer, Bens, O. and Huettl, R. F. (2015) Quantification of mechanical strength and sliding stability of an artificial water catchment (Chicken Creek) Soil & Tillage Research, 146 . pp. 66-78.

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Abstract

Natural shear forces due to gravity along inclined terrain surfaces are controlled by the inclination of the terrain, material composition and its mechanical properties, stratification and hydraulic stress states. Both shear forces and shear strength under a given inclination of the terrain surface strongly depend on the interaction between mechanical and hydraulic stresses. These internal conditions as well as the interactions between these various components are fundamentals in all nonplanar regions under arable, forest or grassland management and they dominate also under various geoscientific aims. Generally, soil creep is a slow soil movement downslope under gravity. It can occur even on gentle slopes when the shear forces exceed the shear strength of the soil. Deposited material on slopes is more sensitive to such movements than well-developed soils due to the absence of a pronounced soil structure, site and management dependent hydraulic properties and functions, which results in low soil strength. We applied the described measurements and the modelling approaches to investigate and to analyse the stability of an artificially constructed water catchment (Chicken Creek) in the mining district of Cottbus/Germany, where glacial sand was deposited above a clay layer with an inclination of about 3.5%. At the lower part of the catchment, an impermeable barrier (clay wall) was positioned transversally to the main slope. Mechanical and hydraulic parameters of the soil layers were determined on soil samples taken from the field site. The measured values were inserted as input parameters for the finite element model (Plaxis 2D) to simulate soil movements and their effect on the stability of the catchment. The obtained results showed that the kind of construction negatively affected the physical low soil strength (low pre-compression stress) although the bulk density was very high (1.7-1.9 g/cm(3) for the sandy material). Hydraulic conductivity revealed a significant anisotropy with higher hydraulic conductivity values in the horizontal direction. Furthermore, finite element results showed that the design of the newly formed landscape remains weak concerning mass movements too. The high water table in the sandy material in conjunction with low soil strength enhances the downslope movement and increases the shear stress near the clay wall at the lower end of the slope, which finally results in soil creep processes. These results also proof that such geotechnical and modelling approach is also suitable to validate or to predict mass movements and the internal processes responsible for these internal mass erosion. (C) 2014 Elsevier B.V. All rights reserved.

Document Type: Article
Additional Information: Times Cited: 1 Si A
Research affiliation: Kiel University > Faculty of Agricultural and Nutritional Sciences
OceanRep > The Future Ocean - Cluster of Excellence
ISSN: 0167-1987
Projects: Future Ocean
Date Deposited: 20 Oct 2016 11:03
Last Modified: 20 Oct 2016 11:03
URI: http://eprints.uni-kiel.de/id/eprint/32403

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