بررسی تأثیر دما بر مقاومت برشی زهکش نشده رس کائولینیت

نوع مقاله : مقاله پژوهشی

نویسندگان

1 گروه زمین شناسی مهندسی و تکتونیک، دانشکده زمین شناسی، پردیس علوم، دانشگاه تهران

2 گروه زمین شناسی و تکتونیک، دانشکده زمین شناسی، پردیس علوم ، دانشگاه تهران

3 تهران، دانشگاه تهران، دانشکده علوم، گروه زمین شناسی مهندسی

چکیده

بررسی تغییر دما بر مقاومت خاک یکی از موضوعاتی است که در دهه‌های اخیر مورد توجه بسیاری  از محققین قرار گرفته است. در تحقیق حاضر به منظور بررسی تأثیر دما بر مقاومت برشی زهکش نشده (Cu)خاکهای رسی، ابتدا سلولی با قابلیت تغییر و ثابت نگه داشتن دمای نمونه در طول بارگذاری، طراحی و ساخته شد. پس از تعیین ویژگی‌های شاخص نمونه‌ای از خاک رس کائولینیت، آزمایش تعیین مقاومت برشی زهکش نشده بر روی خاک اشباع در دماهای 10 ،20 ،30 ،40 ،50 ،60 و70 درجه سانتی گراد انجام گردید. با تکرار آزمایش بر روی نمونه هایی با ویژگی های ثابت و در دمای مشخص تکرارپذیری نتایج تأیید شد. نتایج نشان می‌دهد با افزایش دما، Cu کائولینیت کاهش یافته بطوریکه افزایش دما از 10 درجه به 70 درجه سانتی گراد باعث کاهش مقدار Cu از 26/6 به 10/94 کیلوپاسکال شده است. بر این اساس، در محدوده دمایی مورد مطالعه رابطه ای تجربی بین دما و Cu( با ضریب تعیین 0/96 )برای رس مورد مطالعه پیشنهاد شد. شکل کلی منحنیهای تنش – کرنش نمونه ها در دماهای مختلف یکسان بوده و در کرنش 20 %بصورت خطی در می‌آیند. افزایش دما باعث کاهش محدوده تغییر شکل الاستیک و افزایش محدوده تغییر شکل پلاستیک نمونه ها شده و زاویه صفحه گسیختگی با افق، با افزایش ( AES )نشان دهنده افزایش آن با افزایش دما کاهش می‌یابد. اندازه‌گیری تنش ناشی از انبساط محوری نمونه دما است.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Investigation of the Effect of Temperature on the Undrained Shear Strength of Kaolinite

نویسندگان [English]

  • Akbar Cheshomi 1
  • Fariborz Mohammadi 2
  • Alimohammad Rajabi 3
1 Department of Structural and Engineering Geology, School of Geology, College of Science, University of Tehran
2 Department of Structural and Engineering Geology, School of Geology, College of Science, University of Tehran
3 Department of Structural and Engineering Geology, School of Geology, College of Science, University of Tehran
چکیده [English]

Investigation of the effect of temperature on soil strength is one of the issues which has been considered by many researchers in recent decades. In this study to investigate the effect of temperature on the undrained shear strength (Cu) of clay soils, a cell with the capability of both changing and keeping fixed the temperature of sample, was designed and constructed. After determining the index properties of samples for Kaolinite clay soil, undrained shear strength (Cu) test was carried out on saturated clay soil at 10, 20, 30, 40, 50, 60 and 70 ° C. Repeatability of the results was confirmed by repeating tests on samples with the same properties a given temperature. The results showed that by increasing the temperature, the Cu values decreased so that, as the temperature raised from 10 ° C to 70 ° C, the values Cu were reduced from 26.6 to 10.94 kPa. Accordingly, in the studied temperature range, an empirical relationship between temperature and Cu (with R2 = 0.96) was proposed. The general shape of the stress–strain curves of the samples in different temperature was the same and in strain level of 20% was linear. Increasing the temperature caused to decline in the range of elastic deformation and enhancement in the range of plastic deformation of the samples; in addition, by increasing the temperature, the angle of the failure plane was decreased. The measurement of axial expansion stress (AES) indicated enhancement of the stress by increasing the temperature.

کلیدواژه‌ها [English]

  • Temperature
  • Kaolinite
  • Undrained Shear Strength
  • Clay soil
  • failure
[1]R.G. Campanella, J.K, Mitchell, Influence of temperature variations on soil behavior, Journal of Soil Mechanics & Foundations Div. 1968.
[2]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, 3(28) (2004) 228-209.
[3]D. De Bruyn, J.F. Thimus, The influence of temperature on mechanical characteristics of Boom clay: the results of an initial laboratory programme, Engineering Geology, -1(41(4 (1996) 126-117.
[4]L. Laloui, Thermo-mechanical behaviour of soils, Revue française de génie civil, 6(5( (2001) 843-809.
[5]N. Yavari, A.M. Tang, J.M. Pereira, G. Hassen, Effect of temperature on the shear strength of soils and the soil– structure interface, Canadian Geotechnical Journal, 7(53( (2016), 1194-1186.
[6]A. Di Donna, A. Ferrari, L. Laloui, Experimental investigations of the soil–concrete interface: physical mechanisms, cyclic mobilization, and behaviour at different temperatures, Canadian Geotechnical Journal, 4(53( (2015) 672-659.
[7]Li, H., Zhu, Y., Zhang, J. and Lin, C., 2004. “Effects of temperature, strain rate and dry density on compressive strength of saturated frozen clay” Cold regions science and technology, 1(39(, pp.45-39.
[8]M.R. Shirazi, Effect of Temperature on hydro-mechanical behavior of compacted expansive soil, Doctoral dissertation, Eastern Mediterranean University (EMU(Doğu Akdeniz Üniversitesi (DAÜ) (2014).
[9]T. Hueckel, R. Pellegrini, Effective stress and water pressure in saturated clays during heating–cooling cycles, Canadian Geotechnical Journal, 6(29( (1992) 1102-1095.
[10]W.Z. Chen, Y.S. Ma, H.D. Yu, F.F. Li, X.L. Li, X., Sillen, Effects of temperature and thermally-induced microstructure change on hydraulic conductivity of Boom Clay, Journal of Rock Mechanics and Geotechnical Engineering, 3(9( (2017) 395-383.
[11]G. Baldi, T. Hueckel, R. Pellegrini Thermal volume changes of the mineral–water system in low-porosity clay soils, Canadian geotechnical journal, 4(25( (1988)825 -807 .
[12]YJ. Cui, N. Sultan, P. Delage, A thermomechanical model for saturated clays”, Canadian Geotechnical Journal, 3(37( (2000) 620-607.
[13]H.M. Abuel-Naga, D.T. Bergado, A., Bouazza, Thermally induced volume change and excess pore water pressure of soft Bangkok clay, Engineering Geology, 2-1(89( (2007) 154-144.
[14]C. Li, G. Kong, H. Liu, H. Abuel-Naga, Effect of temperature on behavior of red clay–structure interface. Canadian Geotechnical Journal, 1(56( (2018) 134-126.
[15]H. Yu, W. Chen, Z. Gong, Y. Ma, G. Chen, X. Li, Influence of temperature on the hydro-mechanical behavior of Boom Clay. International Journal of Rock Mechanics and Mining Sciences, 108, (2018)197-189 .
[16]R. Bag, A. Rabbani, A., Effect of temperature on swelling pressure and compressibility characteristics of soil. Applied Clay Science, (2017)136 , 7-1.
[17]J. Graham, N. Tanaka, T. Crilly, M. Alfaro, Modified CamClay modelling of temperature effects in clays, Canadian geotechnical journal, 3(38( (2007) 621-608.
[18]P. Kuntiwattanakul, I. Towhata, K.hishi, I., Seko, Temperature effects on undrained shear characteristics of clay, Soils and Foundations, 1(35( (1995) 162-147.
[19]S.L. Houston, W.N. Houston, N.D. Williams, Thermomechanical behavior of seafloor sediments, Journal of Geotechnical Engineering, 11(111( (1995) 1263-1249.
[20]A. Burghignoli, A. Desideri, S., Miliziano, Deformability of clays under non isothermal conditions, RIG, 4 (1992).
[21]K.H. Head, R., Epps, Manual of soil laboratory testing 1, (2( (1980), London: Pentech Press.
[22]G.P. Tschebotarioff, Foundations, retaining and earth structures, (1973) McGraw-Hill Book.
[23]J.V. Parcher, R.E. Means, Soil mechanics and foundations, (1968) Charles E. Merrill, Columbus, Ohio.
[24]K. Terzaghi, R.B. Peck, G. Mesri, Soil mechanics in engineering practice, (1996) John Wiley & Sons.
[25]M.D. Braja, Advanced soil mechanics, (2008) Taylor & Francis, 270, pp.180-170.