TY - JOUR

T1 - Quantification of mechanical strength and sliding stability of an artificial water catchment (Chicken Creek)

AU - Baba, H. Ould

AU - Peth, S.

AU - Horn, R.

AU - Bens, O.

AU - Hüttl, R. F.

N1 - Funding information: The authors acknowledge the financial support by GFZ German Research Centre for Geosciences . The authors are also grateful to W. Gerwin and M. Elmer in the Brandenburg University of Technology at Cottbus for providing data of the monitoring program in the catchment Chicken Creek. Special thanks to Prof. Dr. V. Feeser /CAU Kiel for providing the Plaxis 2D used for the analyses. Many thanks also to Mrs. A. Badorreck/Cottbus for helping during the sampling.

PY - 2015/3/1

Y1 - 2015/3/1

N2 - 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 (1.7-1.9g/cm3 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.

AB - 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 (1.7-1.9g/cm3 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.

KW - Anisotropy

KW - Hydraulic conductivity

KW - Shear strength

KW - Slope stability

KW - Soil creep

UR - http://www.scopus.com/inward/record.url?scp=84911401805&partnerID=8YFLogxK

U2 - 10.1016/j.still.2014.05.013

DO - 10.1016/j.still.2014.05.013

M3 - Article

AN - SCOPUS:84911401805

VL - 146

SP - 66

EP - 78

JO - Soil and Tillage Research

JF - Soil and Tillage Research

SN - 0167-1987

IS - PA

ER -