بررسي اثر تسليح خاك با ژئوگريد بر پارامترهاي مقاومتي بستر راه

Investigation on the Effect of Geogrid Reinforcement on the Strength Parameters of Subgrade

يكي از روش ­هاي افزايش ظرفيت باربري و كنترل ميزان نشست و تغييرشكل خاك در روسازي راه، استفاده از ژئوگريد­ها مي­ باشد. در اين مقاله با مروري بر تحقيقات انجام شده در طول دو دهه ­ي اخير در ارتباط با مكانيزم­ هاي عملكرد ژئوگريد و كاربرد­هاي آن در راه­ سازي، خصوصيات مقاومتي بستر مسلح با ژئوگريد مورد بررسي قرار گرفته است. بررسي­ ها نشان مي­دهد در اثر تسليح خاك با ژئوگريد در خاك­ هاي با ظرفيت باربري كم، خصوصيات مقاومتي خاك از قبيل CBR، چسبندگي، سختي و مدل الاستيسيته، به صورت چشمگيري افزايش مي­يابد ولي تغيير قابل ملاحظه ­اي در زاويه اصطكاك داخلي خاك ايجاد نمي­كند. هرچه خاك بستر ضعيف­ تر باشد، تأثير تسليح با ژئوگريد پررنگ­تر مي­گردد. همچنين در اين مقاله مطالعات صورت­ گرفته در خصوص تعيين پارامتر­هاي طراحي روسازي مسلح­ شده با ژئوگريد و ارزيابي عملكرد ژئوگريد براي روسازي دانه­ اي و روسازي انعطاف­ پذير، ارائه شده است.

In last decade, Geosynthetics as polimerical products have been applied for various use in civil engineering such as reinforcement, separation, filtration, Drainage, Fluid barrier and Protection. Subgrade soil and its properties are very important in the design of road pavement structure and Its main function is to give acceptable base to the pavement from underneath. Since Pavements constructed over soft subgrade having poor strength parameters such as CBR leading to more thickness of the pavement, successful use of geosynthetics is ensured in a given geotechnical application. As it is well-matched and effective in improving the soil properties when appropriately used. A geogrid as a geosynthetic material containing connected parallel sets of tensile ribs with apertures of sufficient size to allow strike-through of surrounding soil, stone, or other geotechnical material is a common form of subgrade reinforcement. Geogrids used in subgrade as a part of road pavement, has primary functions of geosynthetics which are separation and reinforcement. Geogrid have been successfully used to provide a construction platform over subgrades. Due to recent studies, lateral restraint, improved bearing capacity and tensioned membrane effect  are reinforcement mechanisms which have been identified the use of geogrids to reinforce pavement materials. This study investigated the behavior of reinforced subgrade with geogrid and the effect of reinforcement on soil properties. it is considered various research on geogrid use in pavement. It is shown that the composite of geogrid and soil can reduce the desired thickness of aggragate layer.  It is also mentioned that the use of geogrid in pavement system will affect the cohesion of subgrade and improve the mohr-coloumb strength parameter of the soil.