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 OJCE  Vol.6 No.3 , June 2016
Experimental and Numerical Investigation of Stress Condition in Unstable Soil
Abstract: In unstable soils, a special erosion process termed suffusion can occur under the effect of relatively low hydraulic gradient. The critical hydraulic gradient of an unstable soil is smaller than in stable soils, which is described by a reduction factor α. According to a theory of Skempton and Brogan (1994) [1], this reduction factor is related to the stress conditions in the soil. In an unstable soil, the average stresses acting in the fine portion are believed to be smaller than the average stresses in the coarse portion. It is assumed that the stress ratio and the reduction factor for the hydraulic gradient are almost equal. In order to prove this theory, laboratory tests and discrete element modelings are carried out. Models of stable and unstable soils are established, and the stresses inside the sample are analysed. It is found that indeed in unstable soils the coarse grains are subject to larger stresses. The stress ratios in stable soils are almost unity, whereas in unstable soils smaller stress ratios, which are dependent on the soil composition and on the relative density of the soil, are obtained. A comparison between the results of erosion tests and numerical modeling shows that the stress ratios and the reduction factors are strongly related, as assumed by Skempton and Brogan (1994) [1].
Cite this paper: Ahlinhan, M. , Wouya, E. , Tankpinou, Y. , Koube, M. and Adjovi, C. (2016) Experimental and Numerical Investigation of Stress Condition in Unstable Soil. Open Journal of Civil Engineering, 6, 370-380. doi: 10.4236/ojce.2016.63031.
References

[1]   Skempton, W. and Brogan, J.M. (1994) Experiments on Piping in Sandy Gravels. Géotechnique, No. 3, 449-460.
http://dx.doi.org/10.1680/geot.1994.44.3.449

[2]   Kenney, T.C. and Lau, D. (1986) Internal Stability of Granular Filters: Reply. Canadian Geotechnical Journal, 23, 420-423.
http://dx.doi.org/10.1139/t86-068

[3]   Ahlinhan, M.F. (2011) Stability of Non-Cohesive Soils Due to Internal Erosion. PhD Thesis, Leibniz University Hannover, Hannover.

[4]   Ahlinhan, M.F. and Achmus, M. (2010) Experimental Investigation of Critical Hydraulic Gradients of Unstable Soils. Scour and Erosion, San Francisco, 7-10 November 2010, 599-608.
http://dx.doi.org/10.1061/41147(392)58

[5]   Terzaghi, K. and Peck, R.B. (1967) Soil Mechanics in Engineering Practice. John Wiley & Sons, New York.

[6]   Itasca (2003) PFC3D PFC2D User′s Manual. Itasca Consulting Group Inc., Minneapolis.

[7]   tom Woerden, F., et al. (2004) Finite Element and Discrete Element Modeling for the Solution of Spatial Active Earth Pressure Problems. Proceedings of the 2nd Int. PFC-Symposium on Numerical Modeling in Micromechanics via Particle Methods, Kyoto, 28-29 October 2004, 45-50.
http://dx.doi.org/10.1201/b17007-8

[8]   Belheine, N., Plassiard, J.-P., et al. (2009) Numerical Simulation of Drained Triaxial Testing Using 3D Discrete Element Modeling. Computers and Geotechnics, 36, 320-331.
http://dx.doi.org/10.1016/j.compgeo.2008.02.003

 
 
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