مطالعه‌ی تغییرات ضریب نفوذپذیری و میزان نشست پذیری خاک‌های مارنی در اثر اعمال حرارت از دیدگاه ریزساختاری

نوع مقاله : مقاله پژوهشی

نویسندگان

1 استادیار

2 استادیار گروه مهندسی عمران، دانشگاه هرمزگان

3 دانشجوی کارشناسی ارشد مهندسی عمران، دانشگاه هرمزگان

چکیده

حرارت سبب ایجاد تغییرات در رفتار مهندسی خاک‌های رسی می‌شود. استفاده از خاک‌های رسی به عنوان پوشش محافظ در دفن زباله‌های سطح بالا از جمله مواردی است که رس تحت رژیم‌های حرارتی متوسط تا زیاد قرار می‌گیرد. مارن‌ها از جمله نهشته‌های رسوبی هستند که از کانی‌های رسی و کربنات کلسیم تشکیل شده‌اند. وجود کانی‌های رسی و کربنات کلسیم در خاک‌های مارن به شدت در رفتار مهندسی خا ک‌ها تأثیرگذار است. پژوهش حاضر به مطالعه خصوصیات مهندسی خاک های مارنی تحت رژیم‌های حرارتی با نگرش ویژه به تغییرات ضریب نفوذپذیری، نشست پذیری و مقاومت فشاری از منظر ریز ساختاری می‌پردازد. در این راستا پس از تعیین خصوصیات ژئوتکنیکی خاک مارن، نمونه‌های خاک در معرض سطوح حرارتی بین °C ۲۵ تا °C 9۰۰ قرار داده شده است. تغییر مشخصات خاک‌های مارنی در اثر اعمال حرارت از طریق انجام آزمایش‌های مختلف مکانیکی (نفوذپذیری، تحکیم، مقاومت فشاری محدود نشده (UCS ))و آزمایش‌های ریزساختاری (pH ،پراش اشعه ایکس (XRD )و تصویر میکروسکوپ الکترونی روبشی (SEM ))تجزیه و تحلیل شد. پایش ریزساختار خاک‌های مارنی نشان می‌دهد که به دلیل تخریب و شکل‌گیری کانی‌های جدید و همچنین آرایش ذرات خاک و بافت میکروسکوپی تحت رژیم‌های حرارتی، ضریب نفوذپذیری روند افزایشی دارد به نحوی که در دمای °C 500 میزان ضریب نفوذپذیری حدود 245 برابر فزایش یافته است اما در دمای °C 700 بـه دلـیـل تـشـکیل ترکیبات سیمانی ضریب نفوذپذیری حدود 85% کاهش می‌یابد. شایان ذکر است با افزایش اعمال حرارت در حالی که میزان تخلخل روند صعودی دارد اما میزان نشست پذیری کاهش می‌یابد.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Microstructural Analysis of Thermally Induced Changes in Permeability Coefficient and Settlement of Marl Soils

نویسندگان [English]

  • Mohammad Amiri 1
  • Masoud Dehghani 2
  • maedeh papi 3
1 Assistant Professor, Faculty of Engineering, Hormozgan University, Bandar Abbas, Iran.
2 Assistant Professor, University of Hormozgan, Faculty of Engineering, Bandar Abbas, Iran
3 Master Student, University of Hormozgan, Faculty of Engineering.
چکیده [English]

Temperature changes the engineering behavior of clay soils. Clay soils are used as a protective cover for burial of high-level wastes (HLWs), where the soil is exposed to medium to high temperature regimes. Marls are a type of sedimentary deposits consisting of clay minerals and calcium carbonate. These two components can substantially influence the behavior of marl soils from an engineering standpoint. The present study focuses on the engineering characteristics of marl soils under various temperature regimes with an emphasis on the microstructural changes in permeability coefficient, settlement, and compressive strength Therefore, after determining the geotechnical properties of the marl soil, its samples were exposed to temperatures from 25°C to 900°C. The changes in marl soil properties were analyzed via mechanical tests (measuring permeability, consolidation, and uniaxial compressive strength), and microstructural tests (measuring pH and X-Ray diffraction), and scanning electron microscopy (SEM). The microstructural analysis of marl soil samples indicates that due to the deterioration and formation of new minerals as well as soil particle arrangement and microscopic texture; temperature regimes increase the permeability coefficient. However, at 700 °C the formation of cement compounds reduces permeability coefficient by an approximate factor of 50,000.

کلیدواژه‌ها [English]

  • Marl
  • Permeability Coefficient
  • Settlement
  • XRD
  • SEM
[1] E.E. Mon, S. Hamamoto, K. Kawamoto, T. Komatsu, P. Moldrup, Temperature effects on geotechnical properties of kaolin clay: simultaneous measurements of consolidation characteristics, shear stiffness, and permeability using a modified oedometer, GSTF International Journal of Geological Sciences (JGS), 1(1) (2013) 1-10.
[2] H. Ramezanpour, L. Smaelnejad, Study of relationships between different type of erosion and soil properties of marls in Southern Guilan Province, Iran, in:  The 15th International Congress of ISCO, Budapest, Hungary, 2008.
[3] D.O. Wijdenes, P. Ergenzinger, Erosion and sediment transport on steep marly hillslopes, Draix, HauteProvence, France: an experimental field study, Catena, 33(3-4) (1998) 179-200.
[4] F. Lamas, C. Irigaray, J. Chacón, Geotechnical characterization of carbonate marls for the construction of impermeable dam cores, Engineering geology, 66(34) (2002) 283-294.
[5] V.R. Ouhadi, The role of marl components and ettringite on the stability of stabilized marl, McGill University, Montreal, Canada, 1997.
[6] B. Velde, Introduction to clay minerals: chemistry, origins, uses and environmental significance, Chapman and Hall Ltd, 1992.
[7] P. Kassler, The structural and geomorphic evolution of the Persian Gulf, in:  The Persian Gulf, Springer, 1973, pp. 11-32.
[8] R.N. Yong, Geoenvironmental engineering: Contaminated soils, pollutant fate, and mitigation, CRC press, 2000.
[9] V.R, Ouhadi, M. PourZafarani, Characteristics change of kaolinite and bentonite due to heat treatment from micro structural aspects, Sharif Civil Engineering, 30(2) (2015) 65-72.(In Persian)
[10] P.H. Morris, L. Wong, Modification of dredged sediments to produce useful product by heating to high temperatures: Literature review, CRC for Sustainable Tourism, 2005.
[11] W. Chen, Y. Ma, H. Yu, F. Li, X. Li, X. Sillen, Effects of temperature and thermally-induced microstructure change on hydraulic conductivity of Boom Clay, Journal of Rock Mechanics and Geotechnical Engineering, 9(3) (2017) 383-395.
[12] V.R. Ouhadi, S. Hamidi, M. Amiri, Impact of heavy metal contaminants on coefficient of variations of compression index, expansion index and permeability coefficient of bentonite from micro-structural point of view, Civil Engineering and Environmental Engineering Journal of Tabriz University, 45 (81) (2016) 7-17.(In Persian)
[13] C. Cekerevac, L. Laloui, Experimental study of thermal effects on the mechanical behaviour of a clay, International journal for numerical and analytical methods in geomechanics, 28(3) (2004) 209-228.
[14] S. Alamdar, The long-term effects of saline water on fine-grained soils, Tarbiat Modarres University, Tehran, Iran, 1999.(In Persian)
[15] S.L. Houston, H.D. Lin, A thermal consolidation model for pelagic clays, Marine Georesources & Geotechnology, 7(2) (1987) 79-98.
[16] M.V. Villar, A. Lloret, Influence of temperature on the hydro-mechanical behaviour of a compacted bentonite, Applied Clay Science, 26(1-4) (2004) 337-350.
[17] J. Han, Q. Sun, H. Xing, Y. Zhang, H. Sun, Experimental study on thermophysical properties of clay after high temperature, Applied Thermal Engineering, 111 (2017) .458-748
[18] G. James, J. Wynd, Stratigraphic nomenclature of Iranian oil consortium agreement area, AAPG bulletin, .5422-2812 )5691( )21(94
[19] ASTM, American Society for Testing and Materials, Annual Book of ASTM Standards, in: V.4 (Ed.), P.A., Philadelphia, 1992.
[20] P.R. Hesse, A Textbook of Soil Chemical Analysis, William Clowes and Sons, 1971.
[21] V.R, Ouhadi, R. Yong, Experimental and theoretical evaluation of impact of clay microstructure on the quantitative mineral evaluation by XRD analysis, Applied Clay Science, 23(1-4) (2003) 141-148.
[22] F. Zhang, R. Kong, J. Peng, Effects of heating on compositional, structural, and physicochemical properties of loess under laboratory conditions, Applied Clay Science, 152 (2018) 259-266.
[23] J.E. Vidonish, P.J. Alvarez, K. Zygourakis, Pyrolytic remediation of oil-contaminated soils: reaction mechanisms, soil changes, and implications for treated soil fertility, Industrial & Engineering Chemistry Research, 57(10) (2018) 3489-3500
[24] P.L. O'Brien, T.M. DeSutter, F.X. Casey, E. Khan, A.F. Wick, Thermal remediation alters soil properties–a review, Journal of environmental management, 206 (2018) 826-835.
[25] G. Cultrone, C. Rodriguez-Navarro, E. Sebastian, O. Cazalla, M.J. De La Torre, Carbonate and silicate phase reactions during ceramic firing, European Journal of Mineralogy, 13(3) (2001) 621-634.
[26] M. Trindade, M. Dias, J. Coroado, F. Rocha, Mineralogical transformations of calcareous rich clays with firing: a comparative study between calcite and dolomite rich clays from Algarve, Portugal, Applied Clay Science, 42(3-4) (2009) 345-355.
[27] K.R. Reddy, H. Hettiarachchi, N. Parakalla, J. Gangathulasi, J. Bogner, T. Lagier, Hydraulic conductivity of MSW in landfills, Journal of Environmental Engineering, 135(8) (2009) 677-683.
[28] Q. Sun, W. Zhang, H. Qian, Effects of high temperature thermal treatment on the physical properties of clay, Environmental Earth Sciences, 75(7) (2016) 610.
[29] V.R, Ouhadi, R. Yong, A. Goodarzi, M. Safari-Zanjani, Effect of temperature on the re-structuring of the microstructure and geo-environmental behaviour of smectite, Applied Clay Science, 47(1-2) (2010) 2-9.
[30] V.R, Ouhadi, R. Yong, M. Amiri, M. Ouhadi, Pozzolanic consolidation of stabilized soft clays, Applied Clay Science, 95 (2014) 111-118.