ﻣﻄﺎﻟﻌﻪ آب ﺷﺴﺘﮕﯽ در اﺛﺮ ﺗﻨﮓ ﺷﺪﮔﯽ ﻣﻮﺿﻌﯽ آب راﻫﻪ در ﻣﺠﺎورت ﺗﮑﯿﻪ ﮔﺎه ﭘﻞ

Study of scour due to local narrowing of the canal near the bridge abutment

ﺗﮑﯿﻪﮔﺎه ﯾﮏ ﭘﻞ در ﺑﺴﺘﺮ ﯾﮏ آبراﻫﻪ ﻣﻮﺟﺐ ﮐﺎﻫﺶ ﺳﻄﺢ ﻣﻘﻄﻊ و اﻧﻘﺒﺎض ﺟﺮﯾﺎن ﻣﯽﺷﻮد. در ﭼﻨﯿﻦ ﺷﺮاﯾﻄﯽ ﻋﻼوه ﺑﺮ آب ﺷﺴﺘﮕﯽ ﻣﻮﺿﻌﯽ ﺗﮑﯿﻪﮔﺎه ﺳﺎزه، زﻣﯿﻨﻪ ﻻزم ﺑﺮاي وﻗﻮع ﭘﺪﯾﺪه آبﺷﺴﺘﮕﯽ اﻧﻘﺒﺎﺿﯽ ﻧﯿﺰ ﻓﺮاﻫﻢ ﻣﯽﺷﻮد. ﭘﮋوﻫﺶ ﺣﺎﺿﺮ ﺑﺎ ﻫﺪف ﺑﺮرﺳﯽ ﺗﺄﺛﯿﺮ ﺗﻨﮓﺷﺪﮔﯽ ﺑﺮ آبﺷﺴﺘﮕﯽ ﺗﮑﯿﻪﮔﺎه ﭘﻞ در اﺛﺮ ﺗﻨﮓﺷﺪﮔﯽﻫﺎﯾﯽ ﺑﺎ زواﯾﺎي ﻣﺨﺘﻠﻒ اﻧﺠﺎم ﺷﺪ. ﺑﺮاي اﯾﻦ ﻣﻨﻈﻮر، ﺳﻪ زاوﯾﻪ ﺗﻨﮓﺷﺪﮔﯽ ﺑﺎ زواﯾﺎي 60 ،30 و 90 درﺟﻪ در ﻧﻈﺮ ﮔﺮﻓﺘﻪ ﺷﺪ و ﺗﮑﯿﻪﮔﺎهﻫﺎ در ﺳﻪ ﻣﻮﻗﻌﯿﺖ اﺑﺘﺪا وﺳﻂ و اﻧﺘﻬﺎ ﻣﻮرد ﺑﺮرﺳﯽ ﻗﺮار ﮔﺮﻓﺘﻨﺪ. ﻧﺘﺎﯾﺞ اﯾﻦ ﻣﻄﺎﻟﻌﻪ ﻧﺸﺎن داد ﮐﻪ ﺑﺎ ﮐﺎﻫﺶ زاوﯾﻪ ﺑﺮﺧﻮرد ﺗﻨﮓﺷﺪﮔﯽ ﻋﻤﻖ آبﺷﺴﺘﮕﯽ ﮐﺎﻫﺶ ﻣﯽﯾﺎﺑﺪ و ﮐﺎرﺑﺮد ﺷﮑﺎف ﻣﻮﺟﺐ ﮐﺎﻫﺶ آبﺷﺴﺘﮕﯽ ﺗﮑﯿﻪﮔﺎه ﺑﻪ ﻣﯿﺰان درﺻﺪ ﻧﺴﺒﺖ ﺑﻪ ﺣﺎﻟﺖ ﺗﮑﯿﻪﮔﺎه ﺑﺪون شكاف مي گردد

Bridge pillar in the bed of a canal reduces the cross-sectional area and shrinks the flow. In such conditions, in addition to local scouring of the structural support, the necessary ground for the occurrence of contractile scouring phenomenon is also provided. The aim of this study was to investigate the effect of narrowing on the scour of the bridge abutment due to narrowing with different angles. For this purpose, three tightening angles with angles of 30, 60 and 90 degrees were considered and the supports were examined in three positions, beginning, middle and end. The results showed that by reducing the angle of collision, the scour depth decreases and the application of the gap reduces the scour of the abutment by a percentage compared to the abutment without the gap.