Variation of Suction during Wetting of Unsaturated Collapsible Gypseous Soils

  • Authors

    • Ahmed A. H. Al-Obaidi
    • Mohammed Y. Fattah
    • Mohammed Kh. Al-Dorry
    2018-12-13
    https://doi.org/10.14419/ijet.v7i4.37.23621
  • Collapsibility, Gypseous soil, Soaking, Suction, Unsaturated soil, Wetting.
  • Gypseous soils represent as essential soils that exhibit unsaturated behavior that differs completely than their behavior during soaking. Their strength, stiffness, and compressibility are dependent on the degree of saturation.

    The soil used in this research is disturbed natural gypseous soil having three different percentages of gypsum; 55, 30 and 18%. Nine model tests were conducted to investigate the variation of suction, settlement and total vertical stress with time, also, to study the effect of wetting on the volume change of unsaturated gypseous soil. The soil container used with inner dimensions of (length 700× width 700× height 600 mm). A square footing with (100 mm) sides was used. Models in loose, medium and dense soils were prepared. Watermark monitor data logger model 900M was used, with automatic data collection device that measures soil suction in kPa. The saturation process involved the complete saturation until the suction sensors readings approach to zero. The saturation process was established by allowing the water to infiltrate through the soil in upward-direction with a steady flow and head of 2 m.

    For all soil models, the time needed to reach the zero suction (saturation state) increased with the increase of the initial dry density. The initial value of suction for all soils increased with decreasing of the initial water content. The drop in the readings of suction may be due to the effect of gypsum content on the adsorption of water that leads to the saturation of the sensors surrounding area.

     

     

  • References

    1. [1] Al-Obaidi, Q. A. J., Ibrahim, S. F., Schanz, T., 2013. "Evaluation of Collapse Potential Investigated from Different Collapsible Soils". L. Laloui and A. Ferrari (Eds.): Multi-physical Testing of Soils and Shales, SSGG: 117–12.

      [2] Al-Obaidi, A. and Al-Mafragei, I., 2014. Settlement and Collapse of Gypseous Soils" Tikrit Journal of Engineering Sciences .21(1): 1-9.

      [3] ASTM D422, 2001. Standard Test Methods for Particle-Size Analysis of Soils. Annual Book of ASTM Standards, ASTM International, West Conshohocken, PA.

      [4] ASTM D854 2002. Standard Test Methods for Specific Gravity of Soil Solids by Water Pycnometer1. Annual Book of ASTM Standards, ASTM International, West Conshohocken, PA.

      [5] ASTM D3080 2012.Standard Test Methods for Direct Shear Test of Soils under Consolidated Drained Conditions), Annual Book of ASTM Standards, ASTM International, West Conshohocken, PA.

      [6] ASTM D4253 2014. Standard Test Methods for Maximum Index Density and Unit Weight of Soils Using a Vibratory Table), Annual Book of ASTM Standards, ASTM International, West Conshohocken, PA.

      [7] Edlefsen, N. E., and Anderson, A. B. C., 1943. Thermo Dynamics of soil moisture. Hilgardia, 15: 31-298.

      [8] Fattah, M. Y., al-Musawi, H. H. M., Salman, F. A., 2012.Treatment of Collapsibility of Gypseous Soils by Dynamic Compaction, Geotechnical and Geological Engineering Journal, Volume 30, Issue 6:1369-1387.

      [9] Fattah, M. Y., Al-Ani, M. M., Al-Lamy, M. T. A., 2014. Studying Collapse Potential of Gypseous Soils Treated by Groutingâ€, Soils and Foundations Journal, 54(3): 396-404.

      [10] Fredlund, D. G., and Rahardjo, H., 1993. Soil Mechanics for Unsaturated Soils. New York, John Wiley, and Sons, Inc.

      [11] Nashat, I., Al-Mufty, A., 2000.Gypsum Content Determination in Gypseous Soils and Rocks. In 3rd International Jordanian Conference on Mining, 2, Amman, Jordan: 485-492.

      [12] Zhang, R. J., 2008. Gypsiferous Soils: An Engineering Problem, In Sinkholes and the Engineering and Environmental Impacts of Karst". ASCE: 742–749.

      [13] Zhou N., Sheng D., and Carter J. P., 2012. Modelling the Effect of Initial Density on Soil-Water Characteristic Curves. Geotechnique 62(8):669-680.

  • Downloads

  • How to Cite

    A. H. Al-Obaidi, A., Y. Fattah, M., & Kh. Al-Dorry, M. (2018). Variation of Suction during Wetting of Unsaturated Collapsible Gypseous Soils. International Journal of Engineering & Technology, 7(4.37), 79-85. https://doi.org/10.14419/ijet.v7i4.37.23621