تحليل عددي خاكريزهاي راه مسلح به ژيوسل و بررسي پارامترهاي موثر در عملكرد سيستم تسليح با ژيوسل

Numerical Analysis of Geocell Reinforced Road Embankments and Evaluation of Effective Parameters on the Performance of Geocell Reinforcing System

ژيوسل ها از انواع ژيوسينتتيك ها هستند كه اخيراً جهت تسليح خاك به‌كار برده شده اند. با توجه به عملكرد منحصر به‌فرد اين نوع سيستم تسليح (محصوركنندگي بالا ناشي از هندسه سه بعدي)، استفاده از آن ها در حال توسعه بوده و پژوهش‌هاي وسيعي روي آن ها در حال شكل گيري است. مطالعات آزمايشگاهي نسبتاً وسيعي روي سيستم تسليح با ژيوسل صورت گرفته است، اما مطالعه‌ي عددي عملكرد آن ها، كه براي درك رفتار دقيق‌شان لازم است، بندرت انجام شده است. به همين دليل روش هاي تيوري و طراحي موجود براي اين سيستم، بسيار عقب تر از كاربردهاي آن در زمينه هاي مختلف از جمله در راه‌سازي است. لذا در اين پژوهش، به مطالعه‌ي عملكرد سيستم تسليح با ژيوسل در خاكريزهاي راه و عوامل موثر در آن بر مبناي روش عددي تفاضل محدود با استفاده از نرم افزار FLAC3D پرداخته شده و تاثير پارامترهاي خاك درون ژيوسل و نيز نحوه‌ي قرارگيري لايه هاي ژيوسل در عملكرد اين خاكريزها مورد بررسي قرار گرفته است.

The use of reinforced soil has been considered since long ago. Due to the improvement in technology, different kinds of reinforcement, including geosynthetic and steel types, have emerged. Geocells, as a special type of geosynthetic, have recently been used for soil improvement. Their three dimensional geometry causes extreme lateral confinement for infill soil. This phenomenon leads to increased soil deformability and strength properties. The geocell reinforcement system is in the process of practical development due to its several advantages. Based on literature reviews in this field, theories and design methods are far behind applications in the field, especially roadway applications, due to a lack of understanding of their mechanisms and influencing factors. There are rather extensive laboratory studies in the field of geocell reinforcement, but because of its complexity, numerical modeling of geocell reinforcement has rarely been performed and most numerical studies are based on equivalent composite models for representing the strength and stiffness of geocell confined soil. In a composite model, the geocell reinforced soil is replaced with a soil with higher parameters. These parameters are selected based on limited test results performed on geocell reinforced soil. Therefore, generalizing them to other kinds of soil could be accompanied by further errors. In this numerical study, geocell and soil were simulated separately in 3D. Hence, this numerical modeling has no composite assumptions and errors. Also, all key behaviors of the geocell were included completely. In this paper, geocell reinforced road embankments are simulated using the Finite Difference Method (FDM) of FLAC3D. Geocell was simulated using geogrid structural elements, and the elastic–perfectly plastic Mohr–Coulomb model was used for modeling the behavior of soil. In order to verify the modeling, results were compared with the results of a laboratory test, and, then, different factors influencing reinforced embankment performance, including soil properties and the placement of geocell layers, were investigated.