بررسي باربري جانبي تك شمع قايم مجاور شيب خاكي تسليح‌شده با ژيوگريد

INVESTIGATION OF LATERAL RESISTANCE OF SINGLE PILE LOCATED NEAR GEOGRID REINFORCED SLOPE

در اين نوشتار، با مطالعه روي مدل‌هاي كوچك مقياس آزمايشگاهي، تاثير تسليح يك شيب ماسه‌يي بر باربري جانبي تك شمع قايم مجاور شيب با ژيوگريد بررسي شده است. برنامه‌ي مطالعات آزمايشگاهي شامل بررسي تاثير پارامترهاي مختلف بر نحوه‌ي آرايش عناصر تسليح ژيوگريدي، فاصله‌ي شمع از لبه‌ي تاج شيب، ميزان تراكم و زاويه‌ي شيب، طول مدفون، وضعيت اصطكاك جداري، و شكل مقطع شمع بر باربري جانبي تك شمع قايم مجاور شيب است. براساس نتايج، مقدار ظرفيت باربري جانبي بهبود‌يافته‌ي شمع تا حد زيادي به نحوه‌ي آرايش قرارگيري عناصر تسليح وابسته است. مقادير بهينه‌ي d31 و d6/24 (d: قطر شمع) به‌ترتيب براي طول و عرض لايه‌هاي ژيوگريد و d82/2 و d64/1 براي عمق مدفون‌شدگي بالاترين لايه و فاصله‌ي بين لايه‌هاي ژيوگريد پيشنهاد مي‌شود.

It is sometimes possible for a structure resting on vertical piles to be placed near natural or human-made slopes. The behavior of pile foundations that are located near slopes is different from their behavior when they are located at ground level, as piles not only may induce failure in the slope (especially at shallow depths) but also the lateral bearing capacity of the piles themselves may decrease to a great extent due to the nearby slope. There have been many numerical and experimental studies on single or group piles subjected to lateral loads and founded on flat horizontal ground. Whereas there are many studies on single and group piles near sandy slopes reinforced by geogrids, the effect of using slope reinforcement techniques on the behavior of vertical piles subjected to lateral loads near reinforced slopes has not yet been investigated. Consequently, the lack of study in this field, concerning the real behavior of piles in such situations and the effects of soil reinforcement on the lateral resistance of piles near slopes still exists. The main purpose of this investigation is to examine the effect of reinforcing elements on the lateral behavior of a single vertical pile near a sandy slope, and also how to use an appropriate reinforcing layout in a practical way. Therefore, a broad series of conditions, including unreinforced cases, were tested by varying parameters such as: arrangement of geogrid reinforcements, pile distance from the slope crest, relative density of sand, angle of slope, embedded length, shaft roughness and cross section of pile. The results indicate that an improvement in the lateral resistance of the pile intensively depends on the arrangement of geogrid reinforcements. The optimum length and width values of geogrid layers (i.e. the one leading maximum lateral resistance of a single pile) were 31d and 24.6d (d=pile diameter) and 2.82d, 1.64d for the depth of the first layer and spacing between geogrid layers, respectively.