ﺗﺄﺛﯿﺮ ﻻﯾﮥ ﻣﺎﺳﻪاي ﻣﺴﻠﺢ و ﻏﯿﺮﻣﺴﻠﺢ ﺑﺎ و ﺑﺪون ﺳﺘﻮنﻫﺎي ﻣﺎﺳﻪاي ﺑﺮ رﻓﺘﺎر ﻇﺮﻓﯿﺖ ﺑﺎرﺑﺮي- ﻧﺸﺴﺖ رس ﻧﺮم

Effects of unreinforced /reinforced sand layers coupled with / without sand columns on bearing capacity – settlement of soft clay

ﺳﺘﻮنﻫﺎي ﻣﺎﺳﻪاي/ﺳﻨﮕﯽ ﺑﻪ دﻟﯿﻞ اﺟﺮاي ﺳﺎده و ﮐﻢ ﻫﺰﯾﻨﻪ ﺑﻮدن داراي ﮐﺎرﺑﺮدﻫﺎي ﻣﺘﻨﻮع در ﻣﻬﻨﺪس ژﺋﻮﺗﮑﻨﯿﮏ ﻣﯽﺑﺎﺷﻨﺪ. اﯾﻦ روش ﺑﺎﻋﺚ ﻣﺴﻠﺢ ﻧﻤﻮدن ﺧﺎك ﺑﻪ ﻣﻨﻈﻮر اﻓﺰاﯾﺶ ﻇﺮﻓﯿﺖ ﺑﺎرﺑﺮي، ﮐﻨﺘﺮل ﻧﺮخ ﻧﺸﺴﺖ، ﮐﺎﻫﺶ ﻧﺸﺴﺖﻫﺎي ﻧﺎﻣﺘﻘﺎرن و ﮐﻞ، ﭘﺎﯾﺪاري ﺳﻄﻮح ﺷﯿﺒﺪار و ﻣﻘﺎوﻣﺖ در ﺑﺮاﺑﺮ رواﻧﮕﺮاﯾﯽ ﻣﯽﺷﻮد. ﺧﺎكﻫﺎي رﺳﯽ ﻧﺮم ﮐﻪ در زﻣﺮه ﺧﺎكﻫﺎي ﻣﺸﮑﻞﺳﺎز ﻗﺮار ﻣﯽﮔﯿﺮﻧﺪ از ﻇﺮﻓﯿﺖ ﺑﺎرﺑﺮي ﮐﻢ و ﭘﺘﺎﻧﺴﻞ ﻧﺸﺴﺖ ﺑﺎﻻﯾﯽ ﺑﺮﺧﻮردار ﺑﻮده و از اﯾﻦ رو ﻧﯿﺎز ﺑﻪ ﺑﻬﺴﺎزي دارﻧﺪ. در ﻣﻘﺎﻟﮥ ﺣﺎﺿﺮ ﺗﺄﺛﯿﺮ ﻻﯾﮥ ﺳﻄﺤﯽ ﻣﺎﺳﻪاي ﺑﻪ ﺻﻮرت ﻣﺴﻠﺢ و ﻏﯿﺮﻣﺴﻠﺢ ﻫﻤﺮاه ﺑﺎ و ﺑﺪون ﺗﮏ و ﮔﺮوه ﺳﺘﻮنﻫﺎي ﻣﺎﺳﻪاي ﺑﺮ رﻓﺘﺎر ﻇﺮﻓﯿﺖ ﺑﺎرﺑﺮي-ﻧﺸﺴﺖ رس ﻧﺮم ﺑﺮرﺳﯽ ﺷﺪه اﺳﺖ. ﺑﺪﯾﻦ ﻣﻨﻈﻮر رﻓﺘﺎر ﻧﻤﻮﻧﻪﻫﺎي رس ﻧﺮم، رس + ﻻﯾﻪي ﺳﻄﺤﯽ ﻣﺎﺳﻪاي ﻣﺴﻠﺢ و ﻏﯿﺮﻣﺴﻠﺢ، رس + ﺗﮏ/ﮔﺮوه ﺳﺘﻮنﻫﺎي ﻣﺎﺳﻪاي و رس + ﻻﯾﮥ ﺳﻄﺤﯽ ﻣﺎﺳﮥ ﻣﺴﻠﺢ/ ﻏﯿﺮﻣﺴﻠﺢ + ﺗﮏ / ﮔﺮوه ﺳﺘﻮنﻫﺎي ﻣﺎﺳﻪاي ﺑﺮرﺳﯽ و ﻧﺘﺎﯾﺞ در ﻣﻘﺎﻟﻪ ﺣﺎﺿﺮ اراﺋﻪ ﮔﺮدﯾﺪه اﺳﺖ. از ژﺋﻮﮔﺮﯾﺪ ﺑﻪ ﻋﻨﻮان ﻋﺎﻣﻞ ﺗﺴﻠﯿﺢ ﻻﯾﻪي ﻣﺎﺳﻪاي، از دﺳﺘﮕﺎه ﺳﯽ. ﺑﯽ. آر. ﺑﻪ ﻣﻨﻈﻮر ﺳﯿﺴﺘﻢ ﺑﺎرﮔﺬاري و از ﺻﻔﺤﮥ ﻓﻠﺰي ﺑﻪ ﻗﻄﺮ 5 ﺳﺎﻧﺘﯿﻤﺘﺮ ﺑﻪ ﻋﻨﻮان ﺳﻄﺢ ﺑﺎرﮔﺬاري در آزﻣﺎﯾﺶﻫﺎ اﺳﺘﻔﺎده ﺷﺪه اﺳﺖ. ﻧﺘﺎﯾﺞ آزﻣﺎﯾﺸﺎت ﻧﺸﺎن ﻣﯽدﻫﺪ ﮐﻪ ﺑﻪ ﮐﺎرﮔﯿﺮي ﻻﯾﮥ ﺳﻄﺤﯽ ﻣﺎﺳﮥ ﻏﯿﺮﻣﺴﻠﺢ و ﻣﺴﻠﺢ ﺷﺪه ﺑﺎ ﯾﮏ ﻻﯾﮥ ژﺋﻮﮔﺮﯾﺪ در ﻧﺴﺒﺖ ﻧﺸﺴﺖ 5% ﺑﺎﻋﺚ اﻓﺰاﯾﺶ ﻇﺮﻓﯿﺖ ﺑﺎرﺑﺮي ﺑﯿﻦ 4 ﺗﺎ 7 ﺑﺮاﺑﺮ ﻧﺴﺒﺖ ﺑﻪ رس ﻧﺮم ﺑﻪ ﺗﻨﻬﺎﯾﯽ ﺷﺪه و اﺳﺘﻔﺎده از ﺗﮏ ﯾﺎ ﮔﺮوه ﺳﺘﻮنﻫﺎي ﻣﺎﺳﻪاي ﻧﯿﺰ ﺑﻬﺒﻮد ﻇﺮﻓﯿﺖ ﺑﺎرﺑﺮي رس ﻧﺮم را ﺑﺎﻋﺚ ﺷﺪه اﺳﺖ. ﺑﻪ ﮐﺎرﮔﯿﺮي ﻻﯾﮥ ﺳﻄﺤﯽ ﻣﺎﺳﮥ ﻣﺴﻠﺢ و ﻏﯿﺮﻣﺴﻠﺢ ﺗﻮام ﺑﺎ ﺗﮏ ﯾﺎ ﮔﺮوه ﺳﺘﻮنﻫﺎي ﻣﺎﺳﻪاي ﻧﯿﺰ ﻇﺮﻓﯿﺖﻫﺎي ﺑﺎرﺑﺮي را 7 ﺗﺎ 9 ﺑﺮاﺑﺮ ﻧﺴﺒﺖ ﺑﻪ رس ﻧﺮم اﻓﺰاﯾﺶ داده ﮐﻪ ﺑﻬﺒﻮد 700 ﺗﺎ 900 درﺻﺪي اﺳﺖ. ﺑﺎ اﻓﺰاﯾﺶ ﻗﻄﺮ ﺳﺘﻮنﻫﺎي ﻣﺎﺳﻪاي ﻇﺮﻓﯿﺖ ﺑﺎرﺑﺮي ﻧﻬﺎﯾﯽ اﻓﺰاﯾﺶ ﯾﺎﻓﺘﻪ ﺑﻪ ﮔﻮﻧﻪاي ﮐﻪ ﺑﻪ ﮐﺎرﮔﯿﺮي ﮔﺮوه ﺳﺘﻮن ﻣﺎﺳﻪاي ﺑﻪ ﻗﻄﺮ 8 ﺳﺎﻧﺘﯿﻤﺘﺮ ﺑﯿﺸﺘﺮﯾﻦ ﺗﺄﺛﯿﺮ را ﺑﺮ رﻓﺘﺎر ﻇﺮﻓﯿﺖ ﺑﺎرﺑﺮي- ﻧﺸﺴﺖ ﻧﻤﻮﻧﻪﻫﺎي رس + ﺳﺘﻮنﻫﺎي ﻣﺎﺳﻪاي داﺷﺘﻪ اﺳﺖ. ﻫﻤﭽﻨﯿﻦ ﻧﺘﺎﯾﺞ ﮔﻮاه آن اﺳﺖ ﮐﻪ ﺑﻪ ﮐﺎرﮔﯿﺮي ﻻﯾﮥ ﻣﺎﺳﮥ ﺳﻄﺤﯽ ﺑﻪ ﺻﻮرت ﻣﺴﻠﺢ ﯾﺎ ﻏﯿﺮﻣﺴﻠﺢ ﻫﻤﺮاه ﺑﺎ ﮔﺮوه ﺳﺘﻮن ﻣﺎﺳﻪاي ﻣﺆﺛﺮﺗﺮ از ﺗﮏ ﺳﺘﻮن ﻣﺎﺳﻪاي ﻫﻢ ﺣﺠﻢ اﺳﺖ.

In current paper the effects of surface unreinforced / reinforced sand layers coupled with and without single and group sand columns on the bearing capacity – settlement behavior of soft clays has been investigated. In this regard behavior of soft clay, clay + unreinforced / reinforced sand layer, clay + single / group sand piles and clay + unreinforced / reinforced sand layer + single / group piles samples has been assessed. Geogrid was adopted as the reinforcement, a circular plate 5cm in diameter as the loading surface and C.B.R. apparatus as the loading system. Results show that employing unreinforced / reinforced sand layers at a settlement ratio of 5% improves bearing capacity by 4 t0 7 times the soft clay. Coupling the surface unreinforced / reinforced sand layers with single / group sand piles further increases the bearing capacity by 7 to 9 times that of soft clay.