Abstract
Aims
This paper presents a displacement-based model for predicting the relationship between the increase in shear resistance and shear displacement for soils permeated with an entire plant root system.
Methods
The root force in the root system is estimated based on the shear deformation developed in the soil. This displacement-based model takes a number of factors into account, including the distribution of the shear deformation in the soil, the root orientation, the mobilized root forces, and the root properties.
Results
The proposed model reasonably captures the relationship between the increase in the shear resistance (ΔS) and the shear displacement, as shown by a comparison of the predicted results with data from in situ shear tests.
Conclusions
Major findings are the following: (1) the ΔS value increases considerably with increasing b coefficients, which are used to describe the deformed shape of the shear zone, and Young’s moduli of roots at the early stage of shearing; (2) the ΔS value increases significantly with the τ value at large shear deformations; (3) short roots play an important role in the contribution of root systems to the shear resistance of the soil. However, the success of the model relies on the appropriate estimate of the deformation characteristics on the shear zone and the soil-root bond strength.
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References
Abe K, Ziemer R (1991) Effect of tree roots on a shear zone: modeling reinforced shear stress. Can J For Res 21:1012–1019
Coppin NJ, Richards IG (1990) Use of vegetation in civil engineering. Butterworths, London
Docker BB, Hubble TCT (2008) Quantifying root-reinforcement of river bank soils by four Australian tree species. Geomorphology 100:401–418
Fan C-C, Su C-F (2008) Role of roots in the shear strength of root-reinforced soils with high moisture content. Ecol Eng 33:157–166
Fan C-C, Su C-F (2009) Effect of soil moisture content on the deformation behavior of root-reinforced soils subjected to shear. Plant Soil 324:57–69
Fan C-C, Chen Y-W (2010) The effect of root architecture on the shearing resistance of root-permeated soils. Ecol Eng 36:813–826
Gray DH, Leiser AT (1982) Biotechnical slope protection and erosion control. Van Nostrand Reinhold Co., New York, p 267
Gray DH, Ohashi H (1983) Mechanics of fiber reinforcement in sand. J Geotech Eng ASCE 109:335–353
Normaniza O, Faisal HA, Barakbah SS (2008) Engineering properties of Leucaena leucocephala for prevention of slope failure. Ecol Eng 32:215–221
Operstein V, Frydman S (2000) The influence of vegetation on soil strength. Ground Improv 4:81–89
Pollen N, Simon A (2005) Estimating the mechanical effects of riparian vegetation on streambank stability using a fiber bundle model. Water Resour Res 41:W07025
Shewbridge SE, Sitar N (1989) Deformation characteristics of reinforced sand in direct shear. J Geotech Eng ASCE 115:1134–1147
Shewbridge SE, Sitar N (1990) Deformation based model for reinforced sand. J Geotech Eng ASCE 116:1153–1170
Stokes A, Atger C, Bengough AG, Fourcaud T, Sidle RC (2009) Desirable plant root traits for protecting natural and engineered slopes against landslides. Plant Soil 324:1–30
Stolzy LH, Barley KP (1968) Mechanical resistance encountered by roots entering compact soils. Soil Sci 105:297–301
Thomas RE, Pollen-Bankhead N (2010) Modeling root-reinforcement with a fiber-bundle model and Monte Carlo simulation. Ecol Eng 36:47–61
Waldron LJ (1977) The shear resistance of root-permeated homogeneous and stratified soil. Soil Sci Soc Am J 41:843–849
Waldron LJ, Dakessian S (1981) Soil reinforcement by roots: calculation of increased soil shear strength from root properties. Soil Sci 132:427–435
Wu TH, McKinell WP, Swanston DN (1979) Strength of tree roots and landslides on Prince of Wales Island, Alaska. Can Geotech J 16:19–33
Acknowledgments
The author would like to thank Ms. Ya-Shiuan Wu, who helped measure the dimensions of the plant roots and carried out some of the calculations. This research work was sponsored by the National Science Council in Taiwan under grant number NSC 98-2221-E-327-043. This support is gratefully acknowledged.
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Fan, CC. A displacement-based model for estimating the shear resistance of root-permeated soils. Plant Soil 355, 103–119 (2012). https://doi.org/10.1007/s11104-011-1084-4
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DOI: https://doi.org/10.1007/s11104-011-1084-4