Slope stability analysis considering weight of trees and root reinforcement
Abstract
We study the effect of roots of alder trees on soil reinforcement and slope stabilization. Two types of soil, i.e. Marl and Clayey soils and alders of three ages are considered. The slope stability is studied according to the tree indices based on tree age and soil type. The effect of root reinforcement on slope stability is considered by an additional cohesion. The stability analyses are carried out by the FEM. We perform parameter studies considering tree age, soil type and surcharge. The results indicate that soil type is effective on cohesion. The results also showed that with increasing age of trees from 7 to 15 years, the amount of additional root cohesion increased and with the increase of the age of trees to 20 years this amount slightly decreased. Also, with regard to a constant slope geometry, the type of soil and the uniform surcharge pressure, 7-year-old trees have shown better performance in slope stabilization. It has been observed that as the age of alder trees grows, although the amount of additional root cohesion increases, however, due to increased surcharge pressure, the overall slope stability factor decreases.
Keyword : embankment, alder, soil, stabilization, forest road
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References
Ali, N., Farshchi, I., Mu‘azu, M. A., & Rees, S. W. (2012). Soil-root interaction and effects on slope stability analysis. Electronic Journal of Geotechnical Engineering (EJGE) 17(C), 319-328. http://www.ejge.com/2012/Abs12.030.htm
Bischetti, G. B., Chiaradia, E. A., Simonato, T., Speziali, B., Vitali, B., Vullo, P., & Zocco, A. (2005). Root strength and root area ratio of forest species in Lombardy (Northern Italy). Plant Soil, 278, 11-22. https://doi.org/10.1007/s11104-005-0605-4
Cofie, P., Koolen, A. J., & Perdok, U. D. (2000). Measurement of stress–strain relationship of beech roots and calculation of the reinforcement effect of tree roots in soil–wheel systems. Soil and Tillage Research, 57, 1-12. https://doi.org/10.1016/S0167-1987(00)00126-4
Chok, Y. H., Jaksa, M. B., Kaggwa, W. S., & Griffiths, D. V. (2015). Assessing the influence of root reinforcement on slope stability by finite elements. International Journal of Geo-Engineering, 6, 12. https://doi.org/10.1186/s40703-015-0012-5
Docker, B. B., & Hubble, T. C. T. (2008). Quantifying the enhanced soil shear strength beneath four riparian tree species. Geomorphology, 100, 401-418. https://doi.org/10.1016/j.geomorph.2008.01.009
Genet, M., Stokes, A., Salin, F., Mickovski, S. B., Fourcaud, T., Dumail, J. F., & Van Beek, R. (2005). The influence of cellulose content on tensile strength in tree roots. Plant and Soil, 278, 1-9. https://doi.org/10.1007/s11104-005-8768-6
Genet, M., Kokutse, N., Stokes, A., Fourcaud, T., Cai, X., Ji, J., & Mickovski, S. (2008). Root reinforcement in plantations of Cryptomeria japonica D. Don: effect of tree age and stand structure on slope stability. Forest Ecology and Management, 256, 1517-1526. https://doi.org/10.1016/j.foreco.2008.05.050
Gentile, F., Elia, G., & Elia, R. (2010). Analysis of the stability of slopes reinforced by roots. Design and Nature V. 138, 189200. https://doi.org/10.2495/DN100171
Gray, D. H., & Sotir, R. B. (1996). Biotechnical and Soil Bioengineering Slope Stabilization: A Practical Guide for Erosion Control. John Wiley & sons, Inc.
John, B., Pandey, H. N., & Tripathi, R. S. (2001). Vertical distribution and seasonal changes of fine and coarse root mass in Pinus kesiya Royle Ex. Gordon forest of three different ages. Acta Oecologica, 22, 293-300. https://doi.org/10.1016/S1146-609X(01)01118-3
Keyes, M. R., & Grier, C. C. (1981). Above- and below-ground net production in 40-yearsold Douglas-fir stands on low and high productivity sites. Canadian Journal of Forest Research, 11, 599-605. https://doi.org/10.1139/x81-082
Kokutse, N. K., Temgoua, A. G. T., & Kavazović, Z. (2016). Slope stability and vegetation: Conceptual and numerical investigation of mechanical effects. Ecological Engineering, 86, 146-153. https://doi.org/10.1016/j.ecoleng.2015.11.005
Operstein, V., & Frydman, S. (2000). The influence of vegetation on soil strength. Ground Improvement, 4(2), 81-89. https://doi.org/10.1680/grim.2000.4.2.81
Pollen, N., & Simon, A. (2005). Estimating the mechanical effects of riparian vegetation on stream bank stability using a fiber bundle model. Water Resources Research, 41(7), W07025. https://doi.org/10.1029/2004WR003801
Reubens, B., Poesen, J., Danjon, F., Geudens, G., & Muys, B. (2007). The role of fine and coarse roots in shallow slope stability and soil erosion control with a focus on root system architecture: a review. Trees Structure and Function, 21(4), 385-402. https://doi.org/10.1007/s00468-007-0132-4
Roering, J. J., Schmidt, K. M., Stock, J. D., Dietrich, W. E., & Montgomery, D. R. (2003). Shallow landsliding, root reinforcement, and the spatial distribution of trees in the Oregon Coast Range. Canadian Geotechnical Journal, 40(2), 237-253. https://doi.org/10.1139/t02-113
Schmidt, K. M., Roering, J. J., Stock, J. D., Dietrich, W. E., Montgomery, D. R., & Schaub, T. (2001). The variability of root cohesion as an influence on shallow landslide susceptibility in the Oregon Coast Range. Canadian Geotechnical Journal, 38(5), 995-1024. https://doi.org/10.1139/t01-031
Temgoua, A. G. T., Kokutse, N. K., & Kavazović, Z. (2016). Influence of forest stands and root morphologies on hillslope stability. Ecological Engineering, 95, 622-634. https://doi.org/10.1016/j.ecoleng.2016.06.073
Van Beek, L. P. H., Wint, J., Cammeraat, L. H., & Edwards, J. P. (2005). Observation and simulation of root reinforcement on abandoned Mediterranean slopes. Plant and Soil, 278(1-2), 55-74. https://doi.org/10.1007/s11104-005-7247-4
Vergani, C., Schwarz, M., Cohen, D., Thormann, J. J., & Bischetti, G. B. (2014). Effects of root tensile force and diameter distribution variability on root reinforcement in the Swiss and Italian Alps. Canadian Journal of Forest Research, 44(11), 1426-1440. https://doi.org/10.1139/cjfr-2014-0095
Wu, T. H., McKinnell III, V. P., & Swanston, D. N. (1979). Strength of tree roots and landslides on Prince of Wales Island, Alaska. Canadian Geotechnical Journal, 16(1), 19-33. https://doi.org/10.1139/t79-003
Zhou, Y. Y., & Wang, X. M. (2018). Mesomechanics characteristics of soil reinforcement by plant roots. Bulletin of Engineering Geology and the Environment, 78(5), 3719-3728. https://doi.org/10.1007/s10064-018-1370-y