ﺑﻬﺴﺎزي ﻟﺮزه اي ﺳﺪ ﺑﺘﻨﯽ وزﻧﯽ ﺗﻘﻮﯾﺖ ﺷﺪه ﺑﺎ ﺣﺎﺋﻞ ﻧﮕﻬﺪارﻧﺪه آﺳﻔﺎﻟﺘﯽ

Seismic Improvement of Concrete Gravity Dam Strengthened by Asphalt Buttressing

در اﯾﻦ ﭘﮋوﻫﺶ، ﺗﺤﻠﯿﻞ ﻟﺮزهاي ﻏﯿﺮﺧﻄﯽ ﺳﺪ ﺑﺘﻨﯽ وزﻧﯽ ﺗﻘﻮﯾﺖﺷﺪه ﺑﻪ وﺳﯿﻠﻪي ﺣﺎﺋﻞ ﻧﮕﻬﺪارﻧﺪه آﺳﻔﺎﻟﺘﯽ اراﺋﻪ ﺷﺪه اﺳﺖ. ﺣﺎﺋﻞ ﻧﮕﻬﺪارﻧﺪه آﺳﻔﺎﻟﺘﯽ اﯾﺴﺘﺎ در ﭘﺎﯾﯿﻦدﺳﺖ ﺳﺪ ﺑﺘﻨﯽ وزﻧﯽ، اﻏﻠﺐ ﺑﻪ ﻋﻨﻮان ﯾﮏ روش ﺗﻘﻮﯾﺘﯽ ﺑﺮاي ﺑﻬﺒﻮد ﭘﺎﯾﺪاري ﺳﺪﻫﺎي ﻣﻮﺟﻮد در ﻣﻘﺎﺑﻞ ﺑﺎرﮔﺬاري ﻫﯿﺪرواﺳﺘﺎﺗﯿﮑﯽ و ﻟﺮزهاي ﻣﻮرد ﺗﻮﺟﻪ ﻗﺮار ﻣﯽﮔﯿﺮد. ﺟﻬﺖ ﻧﺸﺎن دادن ﺗﺄﺛﯿﺮ ﺣﺎﺋﻞ ﻧﮕﻬﺪارﻧﺪه ﺑﺮ ﺑﻬﺒﻮد ﭘﺎﺳﺦ ﻟﺮزهاي ﺳﺪ وزﻧﯽ ﺑﺘﻨﯽ و ﮐﺎﻫﺶ ﺗﺮكﻫﺎي اﯾﺠﺎد ﺷﺪه در ﻧﺰدﯾﮑﯽ ﺑﺪﻧﻪي ﺑﺎﻻدﺳﺖ و ﺑﻪ دﻧﺒﺎل آن اﻓﺰاﯾﺶ ﭘﺎﯾﺪاري ﺳﺪ، ﭘﺎﺳﺦ ﺳﺪ Koyna در ﮐﺸﻮر ﻫﻨﺪ ﺗﺤﺖ آﻧﺎﻟﯿﺰ و ﺗﺤﻠﯿﻞ ﻗﺮارﮔﺮﻓﺘﻪ ﺷﺪه اﺳﺖ. ﺗﺤﻠﯿﻞﻫﺎي دﯾﻨﺎﻣﯿﮑﯽ ﺧﻄﯽ و ﻏﯿﺮﺧﻄﯽ ﺑﺎ در ﻧﻈﺮ ﮔﺮﻓﺘﻦ رﻓﺘﺎر ﻏﯿﺮﺧﻄﯽ ﺑﺘﻦ ﺑﺎ دﯾﺪﮔﺎه ﺗﺮك ﭘﺨﺸﯽ ﺛﺎﺑﺖ FCM)( ﺑﻪ ﮐﻤﮏ ﻧﺮماﻓﺰار ANSYS ﺟﻬﺖ ﺑﺮرﺳﯽ رﻓﺘﺎر ﻟﺮزهاي ﺳﺎزه اﻧﺠﺎم ﺷﺪهاﻧﺪ. در ﺗﺤﻠﯿﻞﻫﺎ، اﻧﺪرﮐﻨﺶ ﺳﺪ- ﻣﺨﺰن در ﻧﻈﺮ ﮔﺮﻓﺘﻪ ﺷﺪه اﺳﺖ. ﺗﺤﻠﯿﻞﻫﺎ ﺑﺎ اﻋﻤﺎل ﻣﺆﻟﻔﻪﻫﺎي اﻓﻘﯽ و ﻗﺎﺋﻢ ﺷﺘﺎبﻧﮕﺎﺷﺖ زﻣﯿﻦﻟﺮزه Koyna ﺑﻪ ﻣﺪل ﻟﺤﺎظ ﺷﺪهاﻧﺪ. ﻣﺪلﺳﺎزيﻫﺎ ﺗﺤﺖ ﺣﺎﻻﺗﯽ ﮐﻪ در آن، ﺳﺪ ﺑﺪون ﺣﺎﺋﻞ و داراي ﺣﺎﺋﻞ آﺳﻔﺎﻟﺘﯽ ﻣﺘﺼﻞ ﺑﻪ ﺳﻄﺢ ﺑﺪﻧﻪي ﭘﺎﯾﯿﻦدﺳﺖ ﺻﻮرت ﭘﺬﯾﺮﻓﺘﻪ اﺳﺖ. ﺑﻪ ﻣﻨﻈﻮر اﻣﮑﺎن ﺑﺮرﺳﯽ اﺛﺮات ﺣﺎﺋﻞ ﻧﮕﻬﺪارﻧﺪه در ﻓﺼﻞ ﻣﺸﺘﺮك ﺳﺪ و آﺳﻔﺎﻟﺖ، ﺳﻄﺢ ﺗﻤﺎﺳﯽ ﺑﺎ اﺳﺘﻔﺎده از اﻟﻤﺎنﻫﺎي درز ﺑﺎ ﺿﺨﺎﻣﺖ ﺻﻔﺮ ﺗﻌﺮﯾﻒ ﺷﺪه اﺳﺖ. ﻧﺘﺎﯾﺞ آﻧﺎﻟﯿﺰﻫﺎ ﺗﺼﺪﯾﻖ ﻣﯽﮐﻨﺪ ﮐﻪ ﺣﺎﺋﻞ آﺳﻔﺎﻟﺘﯽ ﻣﯽﺗﻮاﻧﺪ ﭘﺎﯾﺪاري ﻟﺮزهاي ﺳﺪ وزﻧﯽ را در ﻣﻘﺎﺑﻠﻪ ﺑﺎ ﻧﯿﺮوﻫﺎي ﻫﯿﺪرودﯾﻨﺎﻣﯿﮑﯽ ﺑﻬﺒﻮد ﺑﺨﺸﺪ ﺑﻪ ﮔﻮﻧﻪاي ﮐﻪ ﺗﺄﺛﯿﺮ ﻗﺎﺑﻞ ﺗﻮﺟﻪ ﺣﺎﺋﻞ آﺳﻔﺎﻟﺘﯽ ﺑﺮ ﺗﻮزﯾﻊ ﻣﻄﻠﻮب ﺗﻨﺶﻫﺎ در ﮐﻞ ﺑﺪﻧﻪ ﺳﺪ و ﻧﯿﺰ ﻣﻤﺎﻧﻌﺖ از اﯾﺠﺎد ﺗﻤﺮﮐﺰ ﺗﻨﺶ و ﮐﺎﻫﺶ ﺗﺮكﺧﻮردﮔﯽ در ﻗﺴﻤﺖ ﺷﮑﺴﺘﮕﯽ ﺑﺪﻧﻪ ﺑﺎﻻدﺳﺖ در ﻧﺰدﯾﮑﯽ ﺗﺎج ﺳﺪ ﻣﺸﺎﻫﺪه ﻣﯽﮔﺮدد و ﺗﺮكﺧﻮردﮔﯽﻫﺎ ﺗﻨﻬﺎ در ﻣﻘﻄﻊ ﺳﻄﺢ ﻣﺸﺘﺮك ﺳﺪ و ﻓﻮﻧﺪاﺳﯿﻮن ﺗﻮﺳﻌﻪ ﻣﯽﯾﺎﺑﻨﺪ و ﺗﺮكﺧﻮردﮔﯽ در ﺣﺎل ﭘﯿﺸﺮوي در ﻗﺴﻤﺖ ﺷﮑﺴﺘﮕﯽ ﺷﯿﺐ ﭘﺎﯾﯿﻦدﺳﺖ ﺑﻪ ﺳﻤﺖ ﺑﺎﻻدﺳﺖ ﺑﺪﻧﻪ ﺳﺪ ﻣﺸﺎﻫﺪه ﻧﮕﺸﺘﻪ ﮐﻪ ﺑﻪ ﺗﺒﻊ آن، ﻣﻨﺘﺞ ﺑﻪ ﺧﺮاﺑﯽ ﮐﻞ ﺳﺪ ﻧﻤﯽﮔﺮدد.

In the present study, seismic analysis of concrete gravity dams strengthened by asphalt buttressing is presented for improving the seismic behavior of the Koyna dam in India subjected to Koyna ground motion. Fluid-Structure interaction is modeled including water compressibility and reservoir bottom absorption. The foundation is considered as rigid. A three-dimensional fixed smeared crack model is used to consider the nonlinear behavior of mass concrete. The analysis is carried out in the time domain by Newmark time integration scheme. Linear and nonlinear behavior of dam models subjected to horizontal and vertical components of selected record have been analysed. In order to investigate the effects of asphalt buttressing on the interface of dam and asphalt, the contact surface is defined using joint elements with a thickness of zero. The results of the analyzes confirm that the asphalt buttressing can improve the stability of the dam due to the pressure applied to the dam in counteracting the hydrostatic and hydrodynamic forces, Also the significant effect of asphalt Buttressing on the optimal distribution of stresses in the entire body of the dam as well as the prevention of stress concentration and reduction of fracture in the upper body near the dam crest show so that the crack at the lower section of the dam and at the interface of the dam and foundation is partially developed with a slower rate, and the cracking at the upper part near the crown of the dam does not spread to the upstream body of the dam and does not cause a total failure. Overall, it can be said that asphalt buttressing can improve the seismic stability of gravity dams by exerting pressure on the dam in opposition to hydrostatic and hydrodynamic loads.