كليدواژه :
آزمايش سه محوري , مخلوط ماسه - دانه هاي EPS , ژئوتكستايل و لنز ماسه يي , تسليح
چكيده فارسي :
استفاده از مصالح مختلف در تركيب با خاك، جهت بهبود رفتار يا سبك سازي آن در حال توسعه است. يكي از انواع مصالح اشاره شده جهت اختلاط با خاك و سبك سازي آن، دانه هاي پلي استايرن منبسط شده (EPS) است. در نوشتار حاضر، جهت بررسي رفتار مخلوط خاك - دانه هاي EPS و همچنين تاثير لايه هاي ژيوتكستايل محصور در لنز ماسه يي در مقاومت آن، تعداد 34 آزمايش سه محوري استاندارد انجام شده است. نتايج نشان مي دهند كه اگرچه دانه هاي EPS سبب سبك شدن مخلوط مي شوند، اما صلبيت كم آن ها سبب افت مقاومت مخلوط نسبت به فقط خاك مي شوند. جهت ايجاد تعادل بين كاهش وزن مخصوص و عدم افت زياد مقاومت مخلوط، مقدار 0٫5٪ جرمي دانه هايEPS در مخلوط مناسب به نظر مي رسد. استفاده از 4 لايه ي ژيوتكستايل محصور در 4 لايه ي لنز ماسه يي در نمونه، ضمن كاهش 25٪ در وزن مخصوص مخلوط، سبب افزايش مقاومت آن در كرنش 3٪ به ميزان 123٪ نسبت به حالت مخلوط غيرمسلح مي شود.
چكيده لاتين :
Nowadays, the use of different materials in combination with the soil has been grown in geotechnical applications. One of these materials is the expanded polystyrene beads (EPS) that are used to reduce the density and provide lightweight fill. To investigate the possibility of the strength enhancement of soil-EPS beads mixture, the number of 34 standard triaxial compression tests with a diameter of 100 mm and a height of 200 mm have been conducted on the soil alone, as well as unreinforced and geotextile reinforced soil-EPS beads mixture with and without sandy lens layers. In addition, 0.5%, 1%, and 2% of EPS beads in weight mixed with sand, four layers of geotextiles, and four layers of sand lens with a thickness of 20 mm were used to prepare the samples. The tests were carried out at three different confining pressures of 100, 200, and 300 kPa up to 15% of axial strain. Test results show that although EPS beads produce lightweight material, their low rigidity and large volume strain lead to the loss of mixture strength. It can be seen that the ultimate strength of the mixture (at a strain rate of 15%) decreases 42%, 65% and 78% for 0.5%, 1% and 2% of EPS beads, respectively, as compared with soil alone. To make a balance between weight loss and loss of strength, the use of 0.5% of EPS beads to mix with sand seems appropriate. To increase the strength of the sand-EPS beads mixture, geotextile layers and sandy lens layers were used. The test results indicate that the geotextile layers encapsulated with sandy lens layers have an influential impact on increasing the strength of mixture. For example, the use of four geotextile layers encapsulated with four sand lens layers gives a 123% increase in the strength compared with the unreinforced sand-EPS beads mixture. Thus, the combination of these two methods significantly increases the resistance of the mixture. On the basis of the study, the concept of sand-EPS beads mixture reinforced by geotextile layers encapsulated with soil lens layers could be used to improve the performance of backfill over soft soil.
