بررسی پارامترهای موثر بر نشست خاک های گچ دار

نوع مقاله: مقاله پژوهشی

نویسندگان

1 فارغ التحصیل دانشگاه آزاد اراک

2 گروه عمران، واحد اهواز، دانشگاه آزاد اسلامی، اهواز، ایران

3 گروه زمین شناسی، واحد اهواز، دانشگاه آزاد اسلامی، اهواز، ایران

چکیده

تحکیم پذیری و پایداری خاک متاثر از وجود املاح در خاک و به ویژه در رابطه با رطوبت می‌باشد و این موضوع یکی از مشکلات در احداث کانال‌های آبیاری و زهکشی است. در این تحقیق تاثیر گچ طبیعی بر خصوصیات خاک محل اجرای کانال آبیاری و زهکشی مورد بررسی قرار گرفت. به منظور دستیابی به جواب‌های منطبق با شرایط بهره برداری، نمونه‌ها از خاک منطقه و محل اجرای کانال،که دارای گچ طبیعی می‌باشند،تهیه گردید. نمونه‌ها بر اساس ترکیب وزنی خاک و گچ طبیعی با درصد های 1% ، 4% ، 10% و 15% با انجام آزمایش شیمیایی استاندارد تعیین درصد گچ انتخاب و به منظور تعیین برخی ویژگی‌های عمومی خاک، آزمایش‌های شناسایی انجام گرفت.برای بررسی نرخ انحلال از آزمایش تحکیم نیز، بدین گونه استفاده شد که بر روی نمونه‌های آب خروجی حاصل از فرآیند تعویض آب مقطر در جام دستگاه تحکیم با پریود زمانی یک روزه، و تحت تنش‌های1، 4 و 8کیلوگرم بر سانتی‌متر مربع ، اندازه گیری EC به مدت یک ماه انجام گرفت. نتایج آزمایش‌ها نشان داد که با افزایش مقدار گچ، نشانه خمیری و وزن مخصوص خشک نمونه های خاک، کاهش یافته ولی نرخ نفوذپذیری و نشست افزایش می‌یابد.از آنجا که در محاسبه میزان نشست خاک‌های گچ‌دار علاوه بردرصد گچ پارامترهایی مانند ضریب فشردگی حجمی و تنش موثر هم تاثیر گذار ند. از این رو در این تحقیق این عوامل مورد بررسی قرار گرفت و با لحاظ آنها رابطه‌ای پیشنهاد شده است.

کلیدواژه‌ها


عنوان مقاله [English]

Investigating Parameters Affecting the Settlement of Gypsum Soils

نویسندگان [English]

  • Navid Khayat 2
  • Ahad Nazarpour 3
2 Department of Civil Engineering, Ahvaz Branch, Islamic Azad University, Ahvaz, Iran.
چکیده [English]

Consolidation and stability of soil is influenced by the presence of minerals in the soil and it is especially related to its moisture and this is a prevalent difficulty in the construction of irrigation and drainage networks. In this research, the effect of natural gypsum on the properties of soil in the location of constructing network was studied. In order to achieve answers which comply with the conditions of operation, samples were prepared from the construction site, where they contain natural gypsum in soil. Samples were selected, based on a weighted combination of soil and natural gypsum, with percentages of 1%, 4%, 10% and 15% and by conducting standard chemical tests to determine the percentage of gypsum and some general properties of soil. In order to assess the rate of dissolution, consolidation test was also conducted and in this process EC was measured for a month in output water samples extracting from the process of replacing distilled water, in a one-day period and under the stresses of 1, 4 and 8 kg/cm^2 in the consolidation device. The results showed that by increasing the amount of gypsum, plasticity index and dry density of soil samples have decreased, but permeability and settlement rates have increased. Since in the calculation of settlement of gypsum-containing soils, in the addition to the percentage of gypsum, parameters such as volumetric compression ratio and stress are effective as well; so, these factors have been investigated in this research a formula has been suggested by considering these factors.

کلیدواژه‌ها [English]

  • Porosity ratio
  • Natural gypsum
  • Soil settlement
  • Permeability

Al-Hadithy, D. K. 2001. Compressibility of saline soils treated with cement. M. Sc. Thesis. Department of Building and Construction. University of Technology of Iraq.

 

Al-Heeti, A. A. H. 1990. The engineering properties of compacted gypsified Soil. M. Sc. Thesis. University of Baghdad. Iraq.

 

Al-Shalhomi, A. Y. 2000. Effect of Phosphogypsum on the engineering characteristics of clayey soil.
M. Sc. Thesis. Civil Engineering Department. College of Engineering University of Mosul. Mosul, Iraq.

 

Anon. 1975. Method of Testing Soils for Civil Engineering Purposes. BS 1377-2. British Standard. British Standards Institution. London. UK.

 

Arakelyan, E. A. 1986 . Characteristics of The determination of the physical properties of gypsum soils. Soil Mech. Found. Eng. 23, 27-29.

 

Arar, A. 1990. Drainage and salinity controls in gypsiferous soils. Agriculture Division Arab Consult. Amman, Jordan.

 

Baiburdi, M. 1990. Principles of Drainage and Soil Improvement. 6th Ed. Tehran University Press. Tehran. Iran. (in Persian)

 

Day, R. W. 2005.  Foundation engineering handbook: design and construction. ASCE Press. McGraw-Hill. New York. USA.

 

Doner, H. E. and Lynn, W. C. 1977. Carbonate, Halide, Sulfate and Sulfide Minerals. In: Dixon, J. B. and Weed, S. B. (Eds.) Minerals in Soil Environments. Soil Science Society of America. Madison.

 

Huda, N. T. AL- Numani. 2010. improvement of the mechanical properties of gypseous soil by additives.  Al-Qadisiya J. Eng. Sci. 3(3): 287-296.

 

Kargar, S., Rahimi, H. and Raisie, A. 2008. The Effect of gypsum on some physical properties of clay soils. The First National Seminar on Geotechnical Problems of Irrigation and Drainage Networks. May 29. Agricultural Engineering Research Institute. Karaj. Iran. (in Persian)

 

Kargar, S., Raisie, A. and Rahimi, H. 2010. The effect of gypsum and its leaching on resistance properties of clay soil. J. Iranian Soil Water Res. 2, 251- 256. (in Persian)

 

Kattab, S. A. 1986. Effect of gypsum on strength of cement treated granular soil and untreated soil. M. Sc. Thesis. Civil Engineering Department. College of Engineering University of Mosul. Mosul. Iraq.

 

Mahmoudi, Sh. and Heidari, A. 1999. Classification and physicochemical properties of gypsum soils in southwest of Gilanegharb. Iranian J. Agric. Sci. 29(2): 299-308. (in Persian)

 

Maksimovich, N. G. and Sergeev, V. L. 1983. Effect of chemical injection stabilization on gypsum stability in foundation of hydraulic structure. Hydrotech. Constr. 17(7): 380-384.

 

Metternicht, G. and Zink, J. A. 2009. Remote Sensing of Soil Salinization Impact on Land Management. CRC Press. Taylor & Francis Group.

 

Petrukhin, V. P. 1993. Construction of Structures on Saline Soils. Balkema Pub.

 

Rahimi, H. 1980. Soil Mechanics. First Ed. Daneshva Fan Pub. (in Persian)

 

Rahimi, H. 2000. Challenges in construction of irrigation canals in anomaly (problematic) soils. Technical Workshop on Canal Construction, Limitations and Solutions. Iranian National Committee on Irrigation and Drainage. Jan. 25. Tehran. Iran. (in Persian).

 

Terleskaya, M. N. and Matonidze, N. V. 1988. Seepage strength of gypsinate foundations of hydraulic structures. Hydrotech. Constr. 21(12): 690-691.

 

Vafaian, M. 1985. An Introduction to Soil Mechanics. Second Ed. Dehkhoda Pub. (in Persian)

 

Watson, A. 1983. Gypsum Crust. In: Goudie, A. S. L. and Pye, K. (Eds.) Chemical Sediments and Geomorphology. Academic Press. London.