ارزﯾﺎﺑﯽ آزﻣﺎﯾﺸﮕﺎﻫﯽ اﺛﺮ اﻟﯿﺎف ﭘﻠﯽ ﭘﺮوﭘﯿﻠﻦ و ﻧﺎﻧﻮﺳﯿﻠﯿﺲ ﺑﺮ ﻣﺸﺨﺼﺎت ژﺋﻮﺗﮑﻨﯿﮑﯽ ﺧﺎك رس

Laboratory Evaluation of polypropylene fibers and nano-SiO2 on geotechnical properties of clayey soils

ﺑﻬﺴﺎزي ﺧﺎﮐﻬﺎي ﻣﺴﺌﻠﻪدار ﺑﻪ ﻋﻨﻮان اﻣﺮي اﺟﺘﻨﺎب ﻧﺎﭘﺬﯾﺮ ﻧﻘﺶ ﻣﻬﻤﯽ در ﭘﺮوژهﻫﺎي ﻋﻤﺮاﻧﯽ دارد. اﺿﺎﻓﻪ ﻧﻤﻮدن ﺑﺮﺧﯽ از اﻓﺰودﻧﯽﻫﺎ ﺑﻪ ﺧﺎك، ﺑﻪ ﻋﻨﻮان ﯾﮑﯽ از روﺷﻬﺎي ﻣﻮﺛﺮ در ﺑﻬﺒﻮد ﻣﺸﺨﺼﻪﻫﺎي رﻓﺘﺎري ﺧﺎك ﻫﻤﻮاره ﻣﺪﻧﻈﺮ ﻣﻬﻨﺪﺳﯿﻦ ژﺋﻮﺗﮑﻨﯿﮏ ﺑﻮده اﺳﺖ. در اﯾﻦ ﭘﮋوﻫﺶ ﺑﻪ ﺑﺮرﺳﯽ اﺛﺮ اﻟﯿﺎف ﭘﻠﯽ ﭘﺮوﭘﯿﻠﻦ و ﻧﺎﻧﻮﺳﯿﻠﯿﺲ در ﺗﺮﮐﯿﺐ ﺑﺎ ﺧﺎك ﺑﻪ ﻋﻨﻮان ﯾﮏ روش ﻧﻮﯾﻦ ﺑﺮاي ﺑﻬﺴﺎزي ﭘﺎراﻣﺘﺮﻫﺎي ﻣﮑﺎﻧﯿﮑﯽ ﺧﺎك اﺳﺘﻔﺎده ﮔﺮدﯾﺪ. ﻫﺪف از اﯾﻦ ﺗﺤﻘﯿﻖ ﺑﺮرﺳﯽ اﺛﺮ اﻓﺰودن ﻧﺎﻧﻮﺳﯿﻠﯿﺲ و اﻟﯿﺎف ﭘﻠﯽ ﭘﺮوﭘﯿﻠﻦ ﺑﺮ روي ﻣﺸﺨﺼﺎت ﺧﺎك رس ﺑﺎ ﭘﻼﺳﺘﯿﺴﯿﺘﻪ ﮐﻢ در آزﻣﺎﯾﺶ ﺗﮏ ﻣﺤﻮري ﻣﯽﺑﺎﺷﺪ. ﺳﻪ ﺗﺮﮐﯿﺐ ﻣﺨﺘﻠﻒ از ﻧﺴﺒﺖﻫﺎي اﻟﯿﺎف ﭘﻠﯽ ﭘﺮوﭘﯿﻠﻦ )%0/25- %0/5 و %1 وزن ﺧﺎك ﺧﺸﮏ( و ﺳﻪ ﺗﺮﮐﯿﺐ از ﻧﺎﻧﻮﺳﯿﻠﯿﺲ )%0/5- %0/75 و %1 وزن ﺧﺎك ﺧﺸﮏ( اﺳﺘﻔﺎده ﺷﺪه اﺳﺖ. ﻧﺘﺎﯾﺞ اﯾﻦ ﭘﮋوﻫﺶ ﻧﺸﺎن ﻣﯽدﻫﺪ ﮐﻪ اﻓﺰودن ﺗﺮﮐﯿﺐ اﻟﯿﺎف ﭘﻠﯽ ﭘﺮوﭘﯿﻠﻦ و ﻧﺎﻧﻮﺳﯿﻠﯿﺲ در ﺧﺎك رس ﺑﺎﻋﺚ اﻓﺰاﯾﺶ ﻣﻘﺎوﻣﺖ ﻓﺸﺎري ﻣﺤﺼﻮر ﻧﺸﺪه و ﻫﻤﭽﻨﯿﻦ اﻓﺰاﯾﺶ ﻣﺪول اﻻﺳﺘﯿﺴﯿﺘﻪ ﻣﯽﮔﺮدد ﮐﻪ ﺑﻪ ﺗﺮﺗﯿﺐ ﺑﺎﻋﺚ اﻓﺰاﯾﺶ 4/69 و 4/17 ﺑﺮاﺑﺮ ﻧﺴﺒﺖ ﺑﻪ رس ﻃﺒﯿﻌﯽ ﺷﺪه اﺳﺖ. ﻫﻤﭽﻨﯿﻦ ﺑﺎ اﺿﺎﻓﻪ ﮐﺮدن ﻧﺎﻧﻮﺳﯿﻠﯿﺲ ﺷﮑﺴﺖ ﻧﻤﻮﻧﻪﻫﺎ ﺑﯿﺸﺘﺮ از ﺗﺮﮐﯿﺐ ﺧﺎك ﺑﺎ اﻟﯿﺎف اﺳﺖ، اﻣﺎ ﺑﺎ اﻓﺰاﯾﺶ ﻣﻘﺎدﯾﺮ اﻟﯿﺎف، ﻣﮑﺎﻧﯿﺰم ﮔﺴﯿﺨﺘﮕﯽ ﻧﻤﻮﻧﻪﻫﺎي اﺻﻼح ﺷﺪه ﺗﻐﯿﯿﺮ ﻣﯽﮐﻨﺪ در ﻧﺘﯿﺠﻪ ﺑﺎ اﻓﺰاﯾﺶ ﻣﻘﺎدﯾﺮ اﻟﯿﺎف، ﮐﺮﻧﺶ ﮔﺴﯿﺨﺘﮕﯽ اﻓﺰاﯾﺶ ﻣﯽﯾﺎﺑﺪ.

Improvement of problematic soils, as an inevitable issue, has an important role in the construction projects. Adding some additive materials to the soil, has been considered as one of the effective procedure in improving characteristics behavior of soils. In this study, the effect of polypropylene fibers and nano-SiO2 in combination with clay was investigated, as a novel method, in order to refining mechanical properties of the soil. The purpose of this research is to investigate the effect of nano-SiO2 and polypropylene fibers on the properties of low plasticity clay by applying Unconfined Compression Test. Three different mixtures of the proportion of polypropylene fibers(0.25 %, 0.5%, and 1% of dry weight of clayey soil) and nano-SiO2 (0.5%, 0.75%, and 1% of dry weight of clayey soil) has been used. The results of this study show that adding the mixture of polypropylene fibers and nano-SiO2 into the clay soils, leads to 4.69% and 4.17% increment of unconfined compressive strength and modulus of elasticity, respectively, in comparison to the untreated clay. Also adding nano-SiO2 to the soil, causes more failure of samples occur respect to the case in in which the soil is getting mixed with fiber, though by increasing the amount of fibers, the failure mechanism of refined samples changes, thus the failure strain increases.