بررسی آزمایشگاهی اثر آرایش قرارگیری ژئوتکستایل در ظرفیت باربری پی روی خاک مسلح

در این پژوهش،، اثر چگونگی قرارگیری ژئوتکستایل در زیر پی در ظرفیت باربری آن بصورت آزمایشگاهی مورد بررسی قرار گرفته است. در این آزمایش‌ها، خاک زیر پی در یک جعبه فولادی به ابعاد 30×25×90 سانتی متر و پی نواری بصورت یک ورق فولادی به ابعاد  2×7/5×25 سانتی متر شبیه‌سازی شده است. تاثیر قرارگیری مسلح کننده‌ها در ظرفیت باربری پی با نه چینش مختلف بصورت تک لایه، دو لایه و سه لایه بصورت پیوسته و غیر‌پیوسته در بعد سوم، مورد بررسی قرار گرفته است. نتایج این تحقیق نشان می‌دهد استفاده از مسلح کننده‌ها بصورت نوارهای منقطع که به‌صورت مناسبی در فضای سه‌بعدی توزیع شده باشند، باعث افزایش بازده تسلیح می‌گردد. در تسلیح چند لایه، استفاده از نوارهای گسسته مسلح‌ کننده‌ها به‌گونه‌ای که نواری واقع در اعماق لایه‌های مجاور زیر یکدیگر قرار نگیرند، باعث افزایش چشمگیر بازده تسلیح خواهد شد.

laboratory investigation of the effect of the geotextile placement pattern on the bearing capacity of footing on reinforced sand

shear strength of the soil as a granular material depends on the stress level, confinement, cohesion. and the friction between its solid particles. geosynthetics are widely used to improve the mechanical properties of the soil. inclusion of geosynthetics as reinforcement elements increases the confinement and the shear strength of the soil. the bearing capacity of foundation on reinforced soil depends on the type, length, depth, and mechanical properties of the reinforcements and their interface with the soil. since the placement pattern ofthe reinforcements has a great impact on the stress distribution within the soil mass, therefore, it could be animportant parameter on the bearing capacity of the foundations on the reinforced soil. proper placement of the reinforcements within the soil mass could be employed to increase the effectiveness of the reinforcements on the bearing capacity improvement of the foundation on the reinforced soil. this paper presents the results of an experimental study on the effect of the pattern of reinforcement placement in reinforced soil on thebearing capacity of a strip foundation. a steel box filled with sand with the dimensions of 100×25×30 cm(length, widths, and height) was used as the test base. the strip footing was simulated by a steel plate withdimensions of 25×7.5×2 cm. the sand used in this study was a poorly graded sand (sp) according to the unified soil classification system. a woven type geotextile was used as reinforcement. the effect of thereinforcement’s placement pattern on the bearing capacity of the foundation was investigated with ninedifferent layouts including single, double, and three-layered reinforcement layouts. all the specimens prepared with a similar initial unit weight and void ratio. the tests conducted using a displacement-controlled loading device. the loading was applied with a rate of 1 mm/second. all the tests repeated at least three times to assure the accuracy and the repeatability of the results. the results of these tests indicated that the bearing capacity of the foundation increases as the length of the reinforcement increases but up to a certain limit and then remains constant. although increasing the number of reinforcements layer increased the bearing capacity of the foundation, however, the effectiveness of the geotextile in the improvement of the bearing capacitydecreased. placement of the reinforcements in a discrete pattern improves the effectiveness of thereinforcement on the bearing capacity improvement. in multi-layer reinforcement layouts, using discrete stripsof reinforcements in each elevation without overlapping with upper- and lower-layers of reinforcements,resulted the maximum efficiency of reinforcements influence in the improvement of the bearing capacity ofthe foundation. in the recent case, for a specific cross-sectional area of the reinforcement, the bearing capacity of the foundation could be increased by 20% using 17% less reinforcement. the results of this study indicate that the layout of the reinforcement pattern is a very important factor in the bearing capacity of foundations onreinforced soil. with a proper placement of reinforcements, the maximum bearing capacity of the foundation could be achieved with a minimum amount of reinforcement material.