Experimental Investigation of Hydro-Mechanical Soil Properties of a Slope Failure

Year 2022, Volume: 9 Issue: 4, 392 - 400, 31.12.2022

Seda Durukan , Ender Başarı

https://doi.org/10.54287/gujsa.1141808

Cited By: 2

Abstract

A sudden slope failure occurred in Manisa possibly due to the effect of water infiltration because of a slightly damaged sewage pipe. Considering that there was no other evidence such as rainfall or any loading conditions to trigger the slope failure, a laboratory investigation on the soil’s unsaturated hydro-mechanical properties was initiated. Slopes are naturally unsaturated soils, and they may lose their stability with increased saturation degrees with water infiltration. Thus, for a proper investigation, the unsaturated hydro-mechanical properties of soils should be determined. The results presented in this study are focused on determining the key parameters to evaluate the slope failure for unsaturated soil conditions. In this regard, hydraulic conductivity and suction characteristics and the shear strength parameters were determined as well as the classical geotechnical properties of the soil. Classification of soil was determined as silty sand which is known to have slight to moderate suction stresses and mostly affected suddenly by water infiltration. A flexible-wall permeability test was run with a falling head procedure and the saturated hydraulic conductivity of the soil sample was measured as 1x10-7 m/s. Suction characteristics were detected by filter paper method, besides, the soil water retention curve of the soil was constructed. The maximum matric suction of the soil was measured as 2887 kPa for an air-dried sample. Following, the shear strength parameters were measured by conventional direct shear test for both dry and soaked conditions. Finally, the friction angle due to suction was calculated to be 1.7 degrees from the results of dry and saturated shear strength parameters.

Keywords

Unsaturated Soils, Matric Suction, Landslides, Slope Stability

References

• ASTM D3080-11 (2011). Standard test method for direct shear test of soils under consolidated drained conditions. American Society for Testing and Materials, Withdrawn Standart.
• ASTM D5084-16 (2016). Standard test method for measurement of hydraulic conductivity of saturated porous materials using a flexible wall permeameter. American Society for Testing and Materials, Active Standart.
• ASTM D5298-16 (2016). Standard test method for measurement of soil potential (suction) using filter paper. American Society for Testing and Materials, Active Standart.
• Batali, L., & Andreea, C. (2016). Slope Stability Analysis Using the Unsaturated Stress Analysis. Case Study. Procedia Engineering, 143, 284-291. doi:10.1016/j.proeng.2016.06.036
• Bai, F. Q., & Liu, S. H. (2012). Measurement of the Shear Strength of an Expansive Soil by Combining a Filter Paper Method and Direct Shear Tests. Geotechnical Testing Journal, 35(3), 451-459. doi:10.1520/GTJ103342
• Bulut, R., & Leong, C. (2008). Indirect Measurement of Suction. Geotechnical and Geological Engineering, 26, 633-644. doi:10.1007/s10706-008-9197-0
• Chowdhury, R. H., & Azam, S. (2016). Unsaturated shear strength properties of a compacted expansive soil from Regina, Canada. Innovative Infrastructure Solutions, 1, 47. doi:10.1007/s41062-016-0047-2
• Durukan, S., & Akıncı, G. (2017). Assessment and statistical evaluation of suction characteristics obtained via filter paper technique on zeolite – bentonite mixtures. Environmental Earth Sciences, 76, 685, 1-13. doi:10.1007/s12665-017-7032-8
• Gan, JK-M, & Fredlund D. G., (1995, September 6-8). Shear Strength Behavior of Two Saprolitic Soils. In: Proceedings of the First International Conference on Unsaturated Soils (UNSAT'95), Paris, France.
• Fattah, M. Y., Salim, N. M., & Irshayyid, E. J. (2017). Determination of the soil–water characteristic curve of unsaturated bentonite–sand mixtures. Environmental Earth Sciences, 76(5), 201. doi:10.1007/s12665-017-6511-2
• Fredlund, D. G., Morgenstern, N. R., & Widger, R. A. (1978). The shear strength of unsaturated soils. Canadian Geotechnical Journal, 15(3), 313-321. doi:10.1139/t78-029
• Intrieri, E., Gigli, G., Mugnai, F., Fanti, R., & Casagli, N. (2012). Design and implementation of a land-slide early warning system. Engineering Geology. 147-148, 124-136. doi:10.1016/j.enggeo.2012.07.017
• Jewell, R. A. & Wroth, C. P. (1987). Direct shear tests on reinforced sand. Geotechnique, 37(1), 53-68. doi:10.1680/geot.1987.37.1.53
• McCartney, J. S., Villar, L. F. S., & Zornberg, J. G. (2007, November 1-3). Estimation of the Hydraulic Conductivity Function of Unsaturated Clays using Infiltration Column Tests. In: Proceedings of the Sixth Brazilian Symposium on Unsaturated Soils, (pp. 321-328), Salvador, Brazil.
• Naidu, S., Sajinkumar, K. S., Oommen, T., Anuja, V. J., Samuel, R. A., & Muraleedharan C. (2018). Early warning system for shallow landslides using rainfall threshold and slope stability analysis. Geoscience Frontiers, 9(6), 1871-1882. doi:10.1016/j.gsf.2017.10.008
• Oh, S., & Lu, N. (2015). Slope stability analysis under unsaturated conditions: Case studies of rainfall-induced failure of cut slopes. Engineering Geology, 184, 96-103. doi:10.1016/j.enggeo.2014.11.007
• Oh, W. T., & Vanapalli, S. K. (2010). Influence of rain infiltration on the stability of compacted soil slopes. Computers and Geotechnics, 37(5), 649-657. doi:10.1016/j.compgeo.2010.04.003
• Seki, K. (2007) SWRC fit - a nonlinear fitting program with a water retention curve for soils having unimodal and bimodal pore structure. Hydrology and Earth System Sciences, 4, 407-437. doi:10.5194/hessd-4-407-2007
• Seki, K., Toride, N., & van Genuchten, M. Th. (2022). Closed-form hydraulic conductivity equations for multimodal unsaturated soil hydraulic properties. Vadose Zone Journal, 21(1), e20168. doi:10.1002/vzj2.20168
• Tang, G., Huang, J., Sheng, D., & Sloan, S. W. (2018). Stability analysis of unsaturated soil slopes under random rainfall patterns. Engineering Geology, 245, 322-332. doi:10.1016/j.enggeo.2018.09.013
• UNSODA. (2022). Unsaturated Soil Hydraulic Database. Database and program for indirect methods of estimating unsaturated hydraulic properties (Accessed: 06/10/2022) URL (https://data.nal.usda.gov/dataset/unsoda-20-unsaturated-soil-hydraulic-database-database-and-program-indirect-methods-estimating-unsaturated-hydraulic-properties)
• van Genuchten, M. Th. (1980). A closed Form Equation for Predicting the Hydraulic Conductivity of Unsaturated Soils. Soil Science Society of American Journal, 44(5), 892-898.
• Vanapalli, S. K., Fredlund, D. G., & Pufahl, D. E. (1996). The Relation Between the Soil-Water Characteristic Curve and the Unsaturated Shear Strength of a Compacted Glacial Till. Geotechnical Testing Journal, 19(3), 259-268. doi:10.1520/GTJ10351J
• Xian, Y., Wei, X., Zhou, H., Chen, N., Liu, Y., Liu, F., & Sun, H. (2022). Snowmelt-triggered reactivation of a loess landslide in Yili, Xinjiang, China: mode and mechanism. Landslides, 19(8), 1843-1860 doi:10.1007/s10346-022-01879-7
• Zhang, L. L., Fredlund, D. G., Fredlund, M. D., & Wilson, G. W. (2014). Modeling the unsaturated soil zone in slope stability analysis. Canadian Geotechnical Journal, 51(12), 1384-1398. doi:10.1139/cgj-2013-0394