بررسی عددی تأثیر سیستم کیسه-خاک در بهبود ظرفیت باربری ژئوتکنیکی خاک بستر

Using of reinforcement elements in improving geotechnical properties of soil has been considered by a human for many years. In recent years, many improvements have been made in the field of improving poor soils and reinforcing them. Soil reinforcement is used as an effective method to improve the soil layers in order to increase the bearing capacity and reduce the settlement. Soil-bag system is one of the new polymer products. That can be used as a soil reinforcing element in various projects. Soil-bag system was developed in order to increase the bearing capacity of the soil and reduce its settlement. The kind of filling materials mostly depends on the application of soil-bag system and availability of materials. The most important characteristic implemented into the structure of soil-bag system is tension strength of the polymer implemented in the bag. Bags implemented into soil-bag system are generally built of polyethylene or polypropylene polymers. When soil-bag system undergoes vertical loading, tension force produced into the bag cover causes to increase vertical force (N), consequently, this causes to increase the force between soil particles (= soil friction coefficient and F=.N). Earth reinforcement using of soil-bag system causes to increase bearing capacity and it causes to minimize transformation of foundation bed influenced by the imposed load. The results of simple pressure test on the foundation reinforcement with soil-bag system by Yongfu Xu show that when soil-bag system is exposed on external load, it exhibits high strength which a fundamental portion of this strength is resulted from tension force generated in the cover of polymeric bag. Of other characteristics of soil bags, the absorption of vibrations resulted from traffic load can be addressed. In this study, the bed soil models in reinforced and non-reinforced conditions have been investigated using numerical method. Numerical studies have been done in three dimensional cases using finite element method (Abaqus). In this method sand and polypropylene polymer bag behavior were defined by using Mohr-coulomb and Elastic- Perfect Plastic models. Also, the effects of soil-bag system in increasing the bearing capacity and reducing settlement were evaluated. Another resistance-based parameters of soil-bag system which was examined in this research, is the effect of internal friction angle of soil on the bearing capacity of soil-bag system. Regarding the results of numerical method, it is observed that the maximum tension concentration in the above-mentioned model is placed in the corners of polymeric bag. The results show that the more is the friction angle between soils particles, the resistance of soil-bag system will also be increased against the external loading. There are proper matching between the results obtained from numerical studies and field studies done by other researchers. The results show that the bearing capacity of reinforced bed is almost 2 times bigger than the non-reinforcement bed.