Consolidated Undrained Monotonic Shearing Response of Hydrophobic Kızılırmak Sand

Öz

Geotechnical properties of hydrophilic (wettable) sands have been widely discussed in the literature. However, sands may gain hydrophobic (non-wettable) properties after being exposed to a hydrophobic agent in the nature. The number of available studies regarding the response of hydrophobic sands is very limited, and mostly focus on their environmental and hydrological aspects. To close this gap, a controlled laboratory testing program, consisting of 18 monotonic strain-controlled consolidated undrained triaxial shear tests, was designed. Tests were performed on fully saturated hydrophilic and hydrophobic re-constituted Kızılırmak sand samples of different relative densities with pore water measurements. Hydrophobic samples were prepared by using 1 and 2 % WD-40 lubricant by mass. The effect of hydrophobic agent was assessed by comparing the stress – excess pore water pressure - strain responses of hydrophobic sand samples with those of conventional (hydrophilic) sand samples. Test results revealed that addition of hydrophobic agent increases the dilatancy of sands at low confining stresses (~100kPa) by decreasing the excess pore water pressure generation. At higher confining stresses (~400kPa) this effect is less pronounced. Moreover, the addition of hydrophobic agent up to 2% by mass does not systematically and significantly change the effective angle of shearing resistance of sand samples, independent of their initial relative density and confining stress levels.

Anahtar Kelimeler

• Kızılırmak sand
• CU triaxial shear test
• hydrophobicity
• WD-40 lubricant
• dilatancy
• density
• effective stress
• critical state
• stress – strain response

Kaynakça

1. Roscoe, K. H., Schofield, A. N., Wroth, C. P., On The Yielding of Soils. Géotechnique, 8(1), 22–53, 1958.
2. Schofield, A. N., Wroth, C. P., Critical State Soil Mechanics, Cambridge, 1968.
3. Schmertmann, J. H., Guidelines for Cone Penetration Test, Performance and Design, Washington, 1978.
4. NAVFAC Design Manual, Naval Facilities Engineering Command, DM-7.01, 1986.
5. Bolton, M. D., The Strength and Dilatancy of Sands. Géotechnique, 36(1), 65–78, 1986.
6. Houlsby, G. T., How the dilatancy of soils affects their behaviour. Proceedings of the 10th European Conference on Soil Mechanics and Foundation Engineering, Florence, Italy, 1991.
7. Terzaghi, K., Peck, R. B., Mesri, G., Soil Mechanics in Engineering Practice, New York, 1996.
8. Andersen, K. H., Schjetne, K., Database of Friction Angles of Sand and Consolidation Characteristics of Sand, Silt, and Clay. Journal of Geotechnical and Geoenvironmental Engineering, 139(7), 1140–1155, 2013.

9. Byun, Y., Lee, J., Influence of Particle Shape of Hydrophobic Granular Materials on Shear Strength. Advances in Civil, Environmental, and Materials Research, Seoul, Korea, 2012.
10. Kim D., Yang H.-J., Yun T. S., Kim B., Kato S., Park S.-W., Characterization of Geomechanical and Hydraulic Properties of Non-Wettable Sands. Proceedings of the 18th International Conference on Soil Mechanics and Geotechnical Engineering, Paris, France, 2013.
11. Standard Test Method for Consolidated Undrained Triaxial Compression Test for Cohesive Soils, ASTM, D-4767, 2011.
12. Tatar, H. M., Consolidated Undrained Shearing Response of Hydrophobic Sands, M.Sc., Middle East Technical University, 2018.
13. Jefferies, M., Been, K., Soil Liquefaction, A Critical State Approach, Abingdon, New York, 2006.