پديد آورندگان :
زمرديان, محمدعلي دانشگاه شيراز - بخش مهندسي آب , عطايي نوقاب, محمد جعفر دانشگاه شيراز - بخش مهندسي آب
چكيده فارسي :
روگذري جريان عمده ترين عامل تخريب سازه هاي خاكي در اثر به وجود آمدن سيلاب به شمار مي آيد؛ به طوري كه 34٪ شكست همه ي سدها و 35٪ شكست سدهاي خاكي در اثر روگذري جريان گزارش شده است. با توجه به كمبود و نياز به مطالعات بيشتر براي درك صحيحي از روند فرسايش ناشي از روگذري، در اين پژوهش سعي شده است كه تاثير تراكم خاك به كمك پردازش تصوير بررسي شود. خاك مورد بررسي براساس طبقه بندي متحد در كلاس ماسه ي لاي دار جاي دارد كه با اعمال 3٪ تراكم نسبي متفاوت به عنوان تيمار، با استفاده از پردازش تصاوير ضبط شده، به بررسي روند فرسايش ناشي از روگذري جريان در خاك ريز پرداخته شد. نتايج رابطه ي مستقيمي بين درصد تراكم نسبي با زمان فرسايش و رابطه ي معكوس آن با نرخ فرسايش را نشان مي دهند. از طرفي نقش پديده سربريده در درصد تراكم نسبي 100٪ و بيشتر از آن بر نرخ و سرعت فرسايش كاملا مشهود است.
چكيده لاتين :
By 2070, approximately 140 million of the world's population will have resided in coastal areas and in the vicinity of rivers and, thus, economist forecast that around 30000 million euro of assets could be dependent on flood protection. A large part of these flood protection systems is old and need replacement and / or adjusted to match safety standards. It requires a significant investment in addition to an increase in population pressure in coastal areas. Eembankment structures are built of erodible (earthen) and/or non-erodible (Concrete) material by humans or formed naturally. These are used as in the flood protection system and water storage for drinking and irrigation, energy production, and recreation purposes. Due to various reasons, such as overtopping, seepage, internal erosion and piping, and slope instability earthen embankments may fail. However, more than 34% dam, 35% earth dams throughout the world, and 30% dam failure in USA during the last 80 years are consider due to overtopping. More than 60% of human casualties resulted from the failure of dams due to the failure of the three large dams (Vajont dam (Italy), John Storm dam (USA) and Mucho dam (India) due to overtopping flow. Heavy rainfall and consequent dramatic increase in water level, or wave attack caused by hurricane and earthquake are regarded as the primary factors in creating overtopping flow. Inadequate free height, limited capacity of weirs, and inaccurate prediction of the most likely flood are among the most well-known human factors. Laboratory experiments are carried on overtopping of embankments consisting of silty sand constructed with different levels of compaction. Digital image processing was employed to investigate the surface variation in embankment due to overtopping erosion with time. The results show that a direct relationship exists between the relative density of soil and erosion duration. It is also an inverse relationship between density and rate of erosion. On other hand, relative compaction has a key role in headcut erosion and is clearly evident that in the rate of erosion.
