تحليل كليدي تاثير فشار متعادل كننده زمين سپر EPB در جابجايي هاي سينه-كار تونل به روش عددي مطالعه موردي تونل انتقال آب ابوذر تهران

A critical analysis of the effect of earth pressure balance (EPB) on displacements of tunnel face by numerical modeling Case study of Abuzar water transitional tunnel

ﻃﺮح ﺗﻮﻧﻞ اﻧﺘﻘﺎل آب اﺑﻮذر ﺑﻪﻣﻨﻈﻮر ﮐﻨﺘﺮل، ﻫﺪاﯾﺖ ﺟﻤﻊآوري آبﻫﺎي ﺳﻄﺤﯽ و ﺳﯿﻼبﻫﺎ، ﮐﺎﻫﺶ آﻻﯾﻨﺪهﻫﺎ در ﺳﻄﺢ ﺷﻬﺮ ﺗﻬﺮان و ﺧﺎرجﺳﺎزي آن ﺗﻮﺳﻂ ﺳﺎﻣﺎﻧﻪ اﻧﺘﻘﺎل ﻣﻨﺎﺳﺐ و اﯾﻤﻦ ﺑﻪ اﺟﺮا در آﻣﺪه اﺳﺖ. ﺣﻔﺮ اﯾﻦ ﺗﻮﻧﻞ ﺑﻪ روش ﻣﮑﺎﻧﯿﺰه و ﺑﻪ ﮐﻤﮏ ﯾﮏ دﺳﺘﮕﺎه TBM از ﻧﻮع ﺳﭙﺮ ﺗﺮﮐﯿﺒﯽ در دو ﺣﺎﻟﺖ ﺑﺎز و ﺑﺴﺘﻪ ﺑﻪ ﺻﻮرت ﺳﭙﺮ ﺗﻌﺎدﻟﯽ ﻓﺸﺎر زﻣﯿﻦ )EPB( اﻧﺠﺎم ﮔﺮﻓﺘﻪ اﺳﺖ. ﭘﺎﯾﺪاري ﺳﯿﻨﻪﮐﺎر در ﺣﺎل ﺣﻔﺎري ﺗﻮﺳﻂ ﺳﭙﺮ ﺗﻌﺎدﻟﯽ ﻓﺸﺎر زﻣﯿﻦ در اﺑﺘﺪاي ﺗﻮﻧﻞ ﺑﻪ ﻓﺎﺻﻠﻪ 1500 ﻣﺘﺮ داراي اﻫﻤﯿﺖ ﻓﻮقاﻟﻌﺎدهاي اﺳﺖ. ﺗﻮﻧﻞ اﺑﻮذر در ﻃﻮل ﻣﺴﯿﺮ داراي روﺑﺎرهﻫﺎي ﺑﺎ ﺿﺨﺎﻣﺖﻫﺎي ﻣﺨﺘﻠﻔﯽ اﺳﺖ. ﺑﻪ اﯾﻦ ﻣﻨﻈﻮر در ﭼﻬﺎر ﻣﻘﻄﻊ در ﻃﻮل ﻣﺴﯿﺮ در ﻓﻮاﺻﻞ 950 ،750 ،500 و 1200 ﻣﺘﺮ از دﻫﺎﻧﻪ ﺗﻮﻧﻞ ﮐﻪ ﻧﺴﺒﺖ ﺿﺨﺎﻣﺖ روﺑﺎره ﺑﻪ ﻗﻄﺮ ﺗﻮﻧﻞ ﺑﻪﺗﺮﺗﯿﺐ 1/10، 1/56 ،1/33 و 1/70 اﺳﺖ، ﻓﺸﺎر ﻧﮕﻬﺪاري ﺳﯿﻨﻪﮐﺎر ﺗﻮﻧﻞ ﺑﺎ اﺳﺘﻔﺎده از روشﻫﺎي ﻣﺨﺘﻠﻒ ﺗﺠﺮﺑﯽ و ﺗﺤﻠﯿﻠﯽ ﺑﺮآورد ﺷﺪه اﺳﺖ. ﺑﻪ ﻋﻠﺖ ﭘﺪﯾﺪه ﻗﻮس ﻓﺸﺎر در ﺑﺎﻻي ﺳﯿﻨﻪﮐﺎر ﺗﻮﻧﻞ ﻣﻘﺪار ﻓﺸﺎر ﻧﮕﻬﺪاري ﺳﯿﻨﻪﮐﺎر ﺑﺮآورد ﺷﺪه از ﻫﺮ ﯾﮏ از روشﻫﺎي ﺗﺠﺮﺑﯽ و ﺗﺤﻠﯿﻠﯽ ﺑﺎ اﻓﺰاﯾﺶ ﺿﺨﺎﻣﺖ روﺑﺎره ﺗﻐﯿﯿﺮ ﭼﻨﺪاﻧﯽ ﻧﺪارد. ﺗﺄﺛﯿﺮ ﻓﺸﺎر ﻧﮕﻬﺪاري اﻋﻤﺎلﺷﺪه ﺑﺮ ﺳﯿﻨﻪﮐﺎر ﺗﻮﻧﻞ ﺣﺎﺻﻞ از روشﻫﺎي ﻣﺨﺘﻠﻒ ﺗﺠﺮﺑﯽ، ﺗﺤﻠﯿﻠﯽ و ﻋﻤﻠﯿﺎﺗﯽ در ﻣﯿﺰان ﺟﺎﺑﻪﺟﺎﯾﯽﻫﺎ ﺑﻪ روش ﻋﺪدي ﺑﺎ اﺳﺘﻔﺎده از ﻧﺮماﻓﺰار ﺳﻪﺑﻌﺪي FLAC3D در ﻣﻘﺎﻃﻊ ﻣﺨﺘﻠﻒ ﺗﻮﻧﻞ ﻣﻮرد ﺑﺮرﺳﯽ و ﺗﺠﺰﯾﻪوﺗﺤﻠﯿﻞ ﻗﺮار ﮔﺮﻓﺘﻪ اﺳﺖ. ﻧﺘﺎﯾﺞ ﻧﺸﺎن ﻣﯽدﻫﺪ ﺑﺎ اﻓﺰاﯾﺶ ﺿﺨﺎﻣﺖ روﺑﺎره ﯾﺎ ﻧﺴﺒﺖ ﺿﺨﺎﻣﺖ روﺑﺎره ﺑﻪ ﻗﻄﺮ ﺗﻮﻧﻞ، ﺑﺎ اﻋﻤﺎل ﻓﺸﺎر ﻧﮕﻬﺪاري ﺳﯿﻨﻪﮐﺎر ﺑﻪ روشﻫﺎي ﺗﺠﺮﺑﯽ و ﺗﺤﻠﯿﻠﯽ، ﻣﯿﺰان ﺟﺎﺑﻪﺟﺎﯾﯽﻫﺎي ﺣﺎﺻﻞ از ﻣﺪلﺳﺎزي ﺳﯿﻨﻪﮐﺎر ﺗﻮﻧﻞ ﺑﺎ ﻧﺮماﻓﺰار ﺳﻪﺑﻌﺪي FLAC3D ﺑﺮاي ﻧﺴﺒﺖ ﺿﺨﺎﻣﺖ روﺑﺎره ﺑﻪ ﻗﻄﺮ ﺗﻮﻧﻞ ﺑﯿﺸﺘﺮ از 1/56، ﺧﯿﻠﯽ ﺑﯿﺸﺘﺮ از ﻧﺴﺒﺖ ﺿﺨﺎﻣﺖ روﺑﺎره ﺑﻪ ﻗﻄﺮ ﺑﺮاﺑﺮ 1/33 اﺳﺖ. اﯾﻦ ﻧﺸﺎن ﻣﯽدﻫﺪ ﺑﻪ ﻋﻠﺖ ﺑﺴﺘﻪ ﺑﻮدن ﺳﯿﺴﺘﻢ ﺣﻔﺮ ﺗﻮﻧﻞ ﺑﻪ روش ﺳﭙﺮ ﻣﺘﻌﺎدل ﮐﻨﻨﺪه ﻓﺸﺎر زﻣﯿﻦ، ﻣﯿﺰان آزادﺳﺎزي ﺗﻨﺶ ﮐﻪ ﻣﻨﺠﺮ ﺑﻪ اﯾﺠﺎد ﭘﺪﯾﺪه ﻗﻮس ﻓﺸﺎر ﻣﯽﮔﺮدد، ﮐﻢﺗﺮ از روشﻫﺎي دﯾﮕﺮ ﺣﻔﺮ ﺗﻮﻧﻞ اﺳﺖ. ﻧﺘﺎﯾﺞ ﻧﺸﺎن ﻣﯽدﻫﺪ ﮐﻪ روشﻫﺎي ﺗﺠﺮﺑﯽ و ﺗﺤﻠﯿﻠﯽ ﺑﺮاﺳﺎس ﭘﺪﯾﺪه ﻗﻮس ﻓﺸﺎر، ﺑﺮآورد ﻣﻨﺎﺳﺒﯽ از ﻓﺸﺎر ﻧﮕﻬﺪاري ﺳﯿﻨﻪﮐﺎر ﺑﺎ اﻓﺰاﯾﺶ ﺿﺨﺎﻣﺖ روﺑﺎره ﺑﺮاي ﺣﻔﺮ ﺗﻮﻧﻞ ﺑﻪ روش ﺳﭙﺮ ﻣﺘﻌﺎدل ﮐﻨﻨﺪه ﻓﺸﺎر زﻣﯿﻦ ﺣﺎﺻﻞ ﻧﻤﯽﻧﻤﺎﯾﻨﺪ. ﻫﻤﭽﻨﯿﻦ ﻧﺘﺎﯾﺞ اﯾﻦ ﺗﺤﻘﯿﻖ ﻧﺸﺎن ﻣﯽدﻫﺪ ﮐﻪ ﻓﺸﺎر ﺑﺮاﺑﺮ ﺣﺪود 90 درﺻﺪ ﺗﻨﺶ اﻓﻘﯽ ﺑﺮﺟﺎ، ﻓﺸﺎر ﻣﻨﺎﺳﺒﯽ ﺑﺮاي ﻧﮕﻬﺪاري ﺳﯿﻨﻪﮐﺎر ﺗﻮﻧﻞ اﺑﻮذر اﺳﺖ

Overburden has different thickness along the Abuzar water transitional tunnel. For this reason, tunnel face support pressure has been estimated for four different sections having ratio of overburden thickness to diameter of 1.1, 1.33, 1.56 and 1.7 respectively by different empirical and analytical methods. Estimated tunnel face support pressure using each of empirical and analytical methods does not have a considerable variation with an increase of the overburden thickness. Effect of face support pressure using different empirical and analytical methods and the practical measured pressure on the values of face displacements of the tunnel have been investigated in four different sections of tunnel by numerical modeling using FLAC3d software. The results show that values of displacements from the tunnel face modeling using FLAC3d software have a considerably greater value for overburden having a thickness of greater than 6.8 m in comparison with the overburden thickness of smaller than 5.8 m. The empirical and analytical methods cannot estimate acceptable value of face support pressure of tunnel with an increase of the overburden thickness for a tunnel excavated by earth pressure balance (EPB).