مطالعه آزمایشگاهی تاثیرات بارانهای اسیدی و قلیایی بر خصوصیات ژئوتکنیکی خاک ریزدانه

نوع مقاله: مقاله پژوهشی

نویسندگان

1 گروه مهندسی عمران، دانشکده عمران، واحد نجف آباد، دانشگاه آزاد اسلامی، نجف آباد، ایران

2 استاد گروه زمین شناسی مهندسی دانشگاه اصفهان

3 عضو هیت علمی گروه مهندسی عمران، دانشکده عمران،واحد نجف آباد، دانشگاه آزاد اسلامی، نجف آباد، ایران

چکیده

در مطالعه پیش رو تاثیرات باران‌های اسیدی و قلیایی بر خصوصیات ژئوتکنیکی خاک رس با پلاستیسیته پایین مربوط به نواحی شمال شرقی اصفهان مورد ارزیابی قرار گرفته است. در این مطالعه آزمایشگاهی جهت بازسازی فرآیند اندرکنش میان باران مصنوعی و خاک از یک سیستم نفوذ آب در خاک خاص استفاده شده است. بدین صورت که نمونه‌های بازسازی شده در قالب‌ها، تحت نفوذ باران‌های اسیدی و قلیایی درpH ها و سال‌های بارش مختلف قرار گرفتند. آزمون‌های حدود اتربرگ، ضریب نفوذپذیری خاک، آزمون ظرفیت باربری کالیفرنیا و مقاومت فشاری محصور نشده نمونه خاک با pH مختلف جهت بررسی تغییرات مکانیکی خاک نسبت به خاک با درجه اسیدیته خنثی(pH=7) انجام شده است. با استفاده از نتایج آزمایش‌های انجام شده اثر نفوذ آب با pH های مختلف بر روی رفتار مکانیکی خاک مورد نظر بررسی شده است. نتایج نشان می‌دهد که بطور کلی با اسیدی تر شدن یا قلیایی تر شدن هر چه بیشتر آب نفوذی مقادیر حدود اتربرگ (حد روانی و شاخص خمیری) نسبت به نمونه با درجه اسیدیته خنثی افزایشی در حدود 6% در شاخص خمیری و 11% در حد روانی را نشان داده است و میزان نفوذپذیری خاک نیز نسبت به نمونه با pH=7 افزایشی چشمگیری داشته است و در مقادیر مقاومت فشاری محصور نشده و شاخص باربری کالیفرنیا نیز روندی کاهشی مشاهده شده است به گونه‌ای که کاهش در برخی از این مقادیر نسبت به نمونه با باران خنثی به بیش از 50% می‌رسد.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Experimental study on the effect of acid and alkaline rains on geotechnical properties of fine-grained soil

نویسندگان [English]

  • mustafa momeni 1
  • Rasoul Ajalloeian 2
  • meysam bayat 3
1 M.Sc, Department of Civil Eng, Najafabad branch, Islamic Azad University, Najafabad, Iran
2 Professor, Department of Engineering Geology, Isfahan University
3 Associate Professor, Department of Civil Eng, Najafabad branch, Islamic Azad University, Najafabad, Iran
چکیده [English]

In the current study, the effects of acid and alkaline rains on the physical properties of a particular type of clay with low plasticity is evaluated. In order to reproduce the process of interaction between artificial rain and soil, an infiltration setup was fabricated. Solutions of diluted sulfuric acid (H2SO4) and dissolved sodium hydroxide (NaOH) were used to create acidic or alkaline rains, respectively. Distilled water was also used as a reference pH value. Subsequently, the reconstituted samples in a mold are infiltrated by acid or alkaline rains in different pH levels and different fluxes of rainfall. Atterberg limits, Coefficient of permeability, California bearing ratio (CBR) test, and unconfined compressive strength (UCS) of the soil samples were evaluated, to investigate the changes of the mechanical properties of the soil after being exposed to acid or alkaline rain. The obtained results indicated that acidic contamination had a strong influence on the strength characteristics of soils, and the mineralogy of the clay fraction as well as the concentration of acid in the pore fluid could significantly influence the stress-strain behavior of studied soil. However, further decrease in pH (pH=3) and increase in rain fluxes (20 years) caused a significant reduction of the strength. Furthermore, the results indicate that the values of the LL, PI and the soil permeability has increased and the unconfined compressive strength and the CBR has decreased as the artificial rain become more acidic or alkaline, and precipitation years increased from one-year to twenty-years.

کلیدواژه‌ها [English]

  • Acid rain
  • Geotechnical Properties
  • Clay
  • CBR Test
  • Unconfined compressive strength

 

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