بررسی علل شکستگی های پوشش بتنی کانال‌ های انتقال آب (مطالعۀ موردی کانال اصلی شبکۀ آبیاری شبانکاره)

نوع مقاله: مقاله پژوهشی

نویسندگان

1 دانشیار موسسه تحقیقات فنی و مهندسی کشاورزی

2 استادیار مرکز تحقیقات کشاورزی و منابع طبیعی همدان

چکیده

این پژوهش به منظور بررسی علل ترک‌خوردگی و تخریب پوشش بتنی کانال اصلی انتقال آب دشت شبانکاره انجام گرفته است. بدین منظور ابتدا در چند نوبت از محل پروژه بازدید , با حفر چال های شناسائی از عمق های مختلف نمونه‌برداری گردیدند. نمونه های اخذ شده مورد آزمایش های شناسایی ، تعیین پتانسیل واگرایی و تعیین میزان گچ قرار گرفت. نتایج بررسی ها نشان داد تخریب های صورت گرفته به واسطه نشست بستر کانال بوده است. این موضوع مشکل آفرین بودن خاک بستر را به اثبات رساند.نتایج آزمایش های واگرایی نشان داد در برخی از نمونه های خاک منطقه پتانسیل واگرایی فیزیکی وجود دارد ولی از آنجائیکه این نوع خاک ها بصورت رگه های با ضخامت کم در نقاط مختلف بدون الگوی خاصی پراکنده اند، نمی تواند عامل اصلی تخریب ها محسوب شود. نتایج آزمایشهای مختلف فیزیکی، شیمیائی و به ویژه مقدار گچ خاک، نشان داد اغلب نمونه ها حاوی مقادیر قابل توجهی گچ از حدود یک تا نزدیک 70 درصد بوده و تخریب ها نیز در مناطقی که میزان گچ در آنها زیاد بوده رخ داده است.بدین ترتیب عوامل ژئوتکنیکی، یعنی وجود توده‌های گچی و فراهم شدن شرایط انحلال در اثر جریان آب، عامل ایجاد ترک خوردگی و تخریب در کانال انتقال آب شبانکاره شناخته شد.

کلیدواژه‌ها


عنوان مقاله [English]

Investigation on Causes of Destruction of Concrete Lining of Irrigation Canals Constructed on Gypsiferrous Soils (A Case Study for Shabankareh Irrigation Network)

نویسندگان [English]

  • Nader Abbasi 1
  • REZA BAHRAMLOO 2
1 Associate Professor, AERI
2 Hamadan Agricultural research center
چکیده [English]

In this research, the reasons of failures in concrete linings in Shabankareh irrigation project were studied.  In this context, a detailed field survey was performed and all concerning  technical reports were studied. In the second stage, several test pits were dug along the canal embankment and soil samples were taken from different depths. All samples were tested for their chemical, physical and mechanical properties. The results of grain size analysis and Atterberg Limits tests showed that most samples werer coarse grained soils with classification of GP, GM, GP-GM and SM according to USCS standards. The results of Pin Hole tests showed that some samples were of medium to highly dispersive type. The results of the chemical tests indicated that the gypsum content of the soils  varied from 2 to 70 percent. Based on the overall results of the field and laboratory investigations, the main causes of the damages to the lining were related to geotechnical properties of the foundation soil. Also, it was concluded that the existence of gypsum particles in the bed materials was mainly responsible for the failures. Finally it was observed that Gypsiferrous soil layers under the lining were easily dissolved and eroded by seepage flow and surface runoff and cavities were formed extensively, which in turn caused lack of support of the concrete slabs, and general failure of the lining.

کلیدواژه‌ها [English]

  • Canal lining
  • Problematic soils
  • Irrigation networks
  • Lining Failure
  • Shabankareh

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