بررسی تاثیر نوع چرخ و وزن محور بر ترک خوردگی روسازی هایآسفالتی به روش المان محدود

ترک های بالا به پایین از مهمترین خرابی های روسازی های آسفالتی محسوب میشوند که سبب کاهش قابل ملاحظه کیفیت روسازی ها خواهند شد. برهم‌کنش بین چرخ و روسازی نقشی تعیین کننده در پیدایش این نوع از خرابی ها ایفا میکند. در این مقاله سعی شده تا با تحلیل ویسکوالاستیک و به روش المان محدود تاثیر تغییرات وزن محور و همچنین تغییرات نوع چرخ بر ترکهای بالا به پایین بررسی شود. برای این منظور تاثیر سه وزن محور 5، 8.2 و 15 تن و دو ترکیب چرخ مختلف (چرخ‌های زوج و عریض) بر ترک‌های بالا به پایین در روسازی مسلح شده با ژئوگرید و غیرمسلح مقایسه شد. نتایج حاصل از این تحقیق نشان می‌دهد که در وزن محور 5 و 8.2 تن ترک‌های بالا به پایین ابتدا در لبه‌های داخلی مسیر حرکت چرخ ظاهر می‌شوند در حالی که، در وزن محور 15 تن این ترک‌ها در فضای بین دو چرخ زودتر از سایر نواحی ایجاد خواهند شد. همچنین مشخص شد که استفاده از چرخ عریض به جای چرخ‌های زوج بر ترک‌های پایین به بالا بیش از ترک‌های بالا به پایین تاثیرگذار خواهد بود. براساس نتایج به دست آمده می‌توان گفت، استفاده از ژئوگرید در زیر لایه آسفالتی عمدتا در کاهش ترک‌های پایین به بالا موثر خواهد بود و تاثیر چندانی در کاهش ترک‌های بالا به پایین نخواهد داشت. علاوه بر این، مقایسه نسبت خرابی به دست آمده نشان می‌دهد که هم در روسازی مسلح و هم در روسازی غیرمسلح خسارت ترک‌های بالا به پایین ناشی از چرخ عریض بیش از چرخ‌های زوج خواهد بود.

Investigation of TopDown Cracking in Asphalt Pavements Using FEM

Topdown cracking (TDC) is among the major forms of asphaltic pavement distresses that significantly affects the serviceability and development of structural failure. Interaction of tire and pavement interaction plays a key role in the initiation of TDC. This study utilizes viscoelastic analysis using finite element modeling to evaluate the influence of axle loads and tire types on the top down cracking in asphaltic pavements. The effect of three axle loads of 5, 8.2 and 15 ton and two tire configurations (conventional dual tire assembly and super single tire) on TDC in Geogrid reinforced and unreinforced pavements has been investigated. The results show that under axle load of 5 and 8.2 ton top down cracking occurs, initialy at the inner edges of the tires, while under axle load of 15 ton its occurence between the tires is sooner than the other zones. Among bottomup cracking (BUC) and TDC, BUC is more sensitive to the variations of tire type. The study also indicates that the reinforcement of pavement using geogrid at the bottom of asphalt layer is more effective on the bottom up cracking than on the top down cracking. By comparison, the super single tire was shown to create more TDC damage ratio than the dual tires assembly in both reinforced and unreinforced pavements. Topdown cracking (TDC) is among the major forms of asphaltic pavement distresses that significantly affects the serviceability and development of structural failure. Interaction of tire and pavement interaction plays a key role in the initiation of TDC. This study utilizes viscoelastic analysis using finite element modeling to evaluate the influence of axle loads and tire types on the top down cracking in asphaltic pavements. The effect of three axle loads of 5, 8.2 and 15 ton and two tire configurations (conventional dual tire assembly and super single tire) on TDC in Geogrid reinforced and unreinforced pavements has been investigated. The results show that under axle load of 5 and 8.2 ton top down cracking occurs, initialy at the inner edges of the tires, while under axle load of 15 ton its occurence between the tires is sooner than the other zones. Among bottomup cracking (BUC) and TDC, BUC is more sensitive to the variations of tire type. The study also indicates that the reinforcement of pavement using geogrid at the bottom of asphalt layer is more effective on the bottom up cracking than on the top down cracking. By comparison, the super single tire was shown to create more TDC damage ratio than the dual tires assembly in both reinforced and unreinforced pavements. Topdown cracking (TDC) is among the major forms of asphaltic pavement distresses that significantly affects the serviceability and development of structural failure. Interaction of tire and pavement interaction plays a key role in the initiation of TDC. This study utilizes viscoelastic analysis using finite element modeling to evaluate the influence of axle loads and tire types on the top down cracking in asphaltic pavements. The effect of three axle loads of 5, 8.2 and 15 ton and two tire configurations (conventional dual tire assembly and super single tire) on TDC in Geogrid reinforced and unreinforced pavements has been investigated. The results show that under axle load of 5 and 8.2 ton top down cracking occurs, initialy at the inner edges of the tires, while under axle load of 15 ton its occurence between the tires is sooner than the other zones. Among bottomup cracking (BUC) and TDC, BUC is more sensitive to the variations of tire type. The study also indicates that the reinforcement of pavement using geogrid at the bottom of asphalt layer is more effective on the bottom up cracking than on the top down cracking. By comparison, the super single tire was shown to create more TDC damage ratio than the dual tires assembly in both reinforced and unreinforced pavements.