تأثير فاصلۀ استقرار آبشكن محافظ نفوذپذير بالادست بر كنترل آبشستگي موضعي دماغه در سري آبشكن‌هاي نفوذناپذير قائم

Impact of Establishment Distance of Permeable Protective Groyne on Local Scouring Depth Control of the Nose on a Series of Vertical Impermeable Groynes

ﯾﮑﯽ از ﻣﻬﻢﺗﺮﯾﻦ ﻣﻼك ﻫﺎ ﺑﺮاي ﻃﺮاﺣﯽ آﺑﺸﮑﻦ، ﭘﺎﯾ ﺪاري ﺧﻮد آﺑﺸﮑﻦ در ﻣﻘﺎﺑﻞ اﺛﺮات ﻣﺨﺮب ﺟﺮﯾﺎن آب در اﻃﺮاف آن اﺳﺖ. اﺳﺘﻔﺎده از آﺑﺸﮑﻦ ﻣﺤﺎﻓﻆ ﻧﻔﻮذﻧﺎﭘﺬﯾﺮ ﯾﮑﯽ از روﺷﻬﺎي ﻣﻘﺎﺑﻠﻪ ﺑﺎ ﭘﺪ ﯾﺪهي ﻓﺮﺳﺎﯾ ﺶ ﻣﻮﺿﻌﯽ در اﻃﺮاف و ﭘﺎي آﺑﺸﮑﻦ اﺳﺖ. در اﯾﻦ ﻣﻄﺎﻟﻌﻪ ﺑﺮاي ﺣﻔﺎﻇﺖ و ﮐﺎﻫﺶ ﻋﻤﻖ ﻓﺮﺳﺎﯾ ﺶ ﻣﻮﺿﻌﯽ دﻣﺎﻏﻪ در ﺳﺮي آﺑﺸﮑﻦﻫﺎي ﻧﻔﻮذﻧﺎﭘﺬﯾﺮ ، از آﺑﺸﮑﻦ ﻣﺤﺎﻓﻆ ﻧﻔﻮذﭘﺬﯾﺮ در ﺑﺎﻻدﺳﺖ اﺳﺘﻔﺎده ﺷﺪه اﺳﺖ. ﺑﻪ اﯾﻦ ﻣﻨﻈﻮر ﺣﺪاﮐﺜﺮ ﻋﻤﻖ ﻓﺮﺳﺎﯾﺶ ﻣﻮﺿﻌﯽ دﻣﺎﻏﻪ ﺑﺮ اي ﺳﺮي آﺑﺸﮑﻦ-ﻫﺎي ﻧﻔﻮذﻧﺎﭘﺬﯾﺮ ﺑﺎ ﺷﺮاﯾﻂ آزﻣﺎﯾﺸﮕﺎﻫﯽ ﺗﻌﯿﯿﻦ ﺷﺪ و ﻋﻤﻖ آﺑﺸﺴﺘﮕﯽ در دو ﺣﺎﻟﺖ ﺑﺪون آﺑﺸﮑﻦ ﻣﺤﺎﻓﻆ و ﺑﺎ آﺑﺸﮑﻦ ﻣﺤﺎﻓﻆ در ﭘﻨﺞ ﻓﺎﺻﻠﻪي ﻣﺨﺘﻠﻒL') 3L' ،2.5L' ،2L' ،1.5L' ،L' : ﻃﻮل آﺑﺸﮑﻦ ﻣﺤﺎﻓﻆ( از اوﻟﯿﻦ آﺑﺸﮑﻦ از ﺳﺮي آﺑﺸﮑﻦﻫﺎي ﻧﻔﻮذﻧﺎﭘﺬ ﯾﺮ، ﺗﻌﯿﯿﻦ و ﻣﻮرد ﺑﺮرﺳﯽ ﻗﺮارﮔﺮﻓﺖ. ﻧﺘﺎﯾﺞ ﻧﺸﺎن ﻣﯽ دﻫﺪ ﮐﻪ اﺳﺘﻘﺮار آﺑﺸﮑﻦ ﻣﺤﺎﻓﻆ ﻧﻔﻮذﭘﺬﯾﺮ در ﺑﺎﻻﺳﺖ ﺳﺮي آﺑﺸﮑﻦﻫﺎي ﺑﺎ ﻃﻮل ﻣﺴﺎوي در ﻓﺎﺻﻠﻪ 3L'از اوﻟﯿﻦ آﺑﺸﮑﻦ، ﺑﺎﻋﺚ ﮐﺎﻫﺶ ﺣﺪاﮐﺜﺮ ﻋﻤﻖ آﺑﺸﺴﺘﮕﯽ اوﻟﯿﻦ آﺑﺸﮑﻦ ﺑﻪ ﻣﯿﺰان 34/3 درﺻﺪ ﻣﯽﺷﻮد.

One of the most important criteria for designing groynes is the stability of groynes during floods passing around them. To be able to protect the riverbank, the groynes should maintain their stability over the years. One of the main reasons for groynes instability is the local scouring around them. In this study, to protect and reduce the maximum local scouring depth of the nose of a series of impermeable groynes, a permeable protective groyne (PPG) is installed upstream. For this purpose, the maximum local erosion depth of the nose of series of impermeable groynes was determined under laboratory conditions and the scour depth in two cases without protective groyne and with protective groyne at five different distances i.e. L', 1.5L', 2L', 2.5L', 3L' (L': Protective groyne Length) at the upstream side of the first groyn was determined and evaluated. The results show that the establishment of permeable protective groyne at the upstream of a series of impermeable groynes with equal length at 3L' distance from the first groynes reduces the maximum local scouring depth of the first groyne by 34.3% at 3L' distance from the first groynes.