تاثیر شوری بر پتانسیل تورم و انقباض خاک‌های متورم شونده تحت چرخه‌های تر و خشک شدن

نوع مقاله: مقاله پژوهشی

نویسندگان

1 دانشجوی کارشناسی ارشد سازه های آبی

2 عضو هیئت علمی

3 استادیار/ دانشگاه محقق اردبیلی

چکیده

خاک‌های متورم شونده از نوع خاک‌های مشکل‌زایی هستند که با تغییر رطوبت، دچار تغییر حجم میشوند. این خاک‌ها معمولاً حاوی مقادیر زیادی رس بوده و مقدار تورم آن‌ها بستگی کامل به نوع کانی‌های رسی و پیوندهای مولکولی دارد. همچنین نوع مواد شیمیایی که با این نوع خاک تماس پیدا می‌کند بر نحوه رفتار آن بسیار اثر گذار می‌باشد. در این پژوهش اثر شوری بر رفتار خاک‌های رسی تحت چرخه‌های تر و خشک بررسی شد. بدین منظور سه نمونه خاک شامل یک نمونه خاک متورم شونده از اطراف دریاچه ارومیه، در حالت بدون شوری و دو نمونه خاک با شوری 2 و 4 درصد وزنی، با استفاده از نمک NaCl تهیه شده و آزمایش تورم آزاد بر روی نمونه‌ها در دستگاه تحکیم و در معرض چرخه‌های تر و خشک انجام گرفت و در نهایت تأثیر شوری بر رفتار خاک بررسی گردید. همچنین در طی آزمایشها میزان نمک‌زدایی نمونه‌ها مورد بررسی قرار گرفت. نتایج حاصله نشان داد میزان تورم و انقباض در چرخه های دوم از بیشترین مقدار برخوردار بوده است. بررسی چرخه‌ها نشان داد که میزان پتانسیل تورم و انقباض پس از پایان حدود 6 چرخه به مقدار نزدیک به 50 درصد کاهش می‌یابد. همچنین نتایج تحقیق حاضر نشان داد که با افزایش غلظت نمک از میزان تورم نمونه‌ها کاسته شده است. با افزودن میزان اندکی نمک پتانسیل تورمی خاک به میزان قابل توجهی کاهش یافت.

کلیدواژه‌ها


عنوان مقاله [English]

The effect of salinity on the swelling behavior of expansive soils under wetting and drying cycles

نویسنده [English]

  • Hojjat Ahmadi 2
چکیده [English]

Expansive soils is known as a problematic soil that shows volume changes while subjected to moisture content variation. Volume changing of such soils, specially the basis of light structure like base of canals with rigid lining lead to cause high costs. This type of soils evolve more clay and the magnitude of expansion depend upon to the type of minerals and molecular connections. Furthermore the type of chemical materials which is added to the soil, precise an explanatory definition of engineering properties of the soil. In this research the effect of salinity on the behavior of clayey soils under wetting and drying cycle was investigated. In this regards, three expansive soil sample including; zero, two and four weighty percent of NaCl were prepared and free swelling tests under wetting and drying cycles with monitoring of salinity variation were conducted. The results of this investigation revealed that the maximum expansive is refer to the second cycle, as well the expansive behavior after 6 cycle decrease significantly. Also, the achievements of this study confirmed that in the specimens including salt the gravity forces between ions over clays and cation increases and it cause to decrease of swelling. Whereas, in the specimens including 4% salinity the minimum expansive was shown that this may practical as a simple method to control the expansive behavior of clays.

کلیدواژه‌ها [English]

  • Engineering properties
  • free swelling
  • NaCl
  • wetting-drying
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