کالیبراسیون مدل‌های ویتزاک و ویتزاک اصلاح شده برای پیشبینی مدول دینامیکی لایه‌های آسفالتی در حال بهره‌برداری

نوع مقاله : مقاله پژوهشی

نویسنده

دانشگاه ارومیه

چکیده

یکی از ورودی‌های مهم روش طراحی روسازی آسفالتی مکانیستیک – تجربی (MEPDG)، مدول دینامیکی (|E*|) است که به عنوان مشخصه رفتار ویسکوالاستیک مخلوط‌های آسفالتی شناخته می‌شود. MEPDG برای تعیین مدول دینامیکی لایه‌های آسفالتی در روسازی‌های در حال بهره‌برداری، از ترکیبی از نتایج آزمایش افت و خیزسنج وزنه افتان (FWD) و مدل‌های پیش‌بینی آزمایشگاهی مدول دینامیکی بهره می‌گیرد. این در حالی است که این روش با چالش‌هایی همراه بوده و نیاز به ارائه مدل‌های دقیق و بهبود روش فعلی احساس می‌شود. در این پژوهش با انجام آزمایش‌های میدانی و آزمایشگاهی در ده سایت روسازی آسفالتی در استان‌های خوزستان و کرمان، به بررسی و تحلیل مدول دینامیکی درجای لایه‌های آسفالتی با استفاده از نتایج محاسبات بازگشتی FWD پرداخته شده است. در هر سایت، آزمایش FWD انجام شده و مغزه‌هایی برای تجزیه و تعیین خصوصیات حجمی مخلوط‌ها و مشخصات ویسکوزیته قیرهای بازیابی گرفته شده است. نتایج این پژوهش نشان می‌دهد با استفاده از مدل‌های پیش‌بینی موجود ویتزاک و ویتزاک اصلاح شده، امکان ساخت مدل‌های جدید درجا با کالیبراسیون این مدل‌ها وجود دارد. با استفاده از مدل‌های جدید توسعه یافته تحت عناوین مدل ویتزاک درجا و مدل ویتزاک اصلاح شده درجا، مدول دینامیکی لایه‌های آسفالتی در حال بهره‌برداری بدون نیاز به انجام آزمایش FWD به طور مستقیم با استفاده از خصوصیات حجمی لایه‌ها و مشخصات ویسکوزیته قیر بازیابی از آنها با دقت پیش‌بینی بالا و اُریب پیش‌بینی پایین تعیین می‌شود. ارزیابی عملکرد و اعتبارسنجی مدل‌های جدید، دقت پیش‌بینی این مدل‌ها را با ضریب تعیین 93/0 نشان می‌دهد.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Calibration of Witczak and Modified Witczak Models for Prediction of Dynamic Modulus of In-Service Asphalt Layers

نویسنده [English]

  • Nader Solatifar
Urmia University
چکیده [English]

One of the important input parameters of the Mechanistic-Empirical Pavement Design Guide (MEPDG) for asphalt pavements is the dynamic modulus (|E*|) that can be defined as the viscoelastic property of asphalt materials. For the determination of dynamic modulus of in-service asphalt layers, MEPDG uses results of both Falling Weight Deflectometer (FWD) and laboratory dynamic modulus predictive models. This method in some cases lacks precision. Hence, it is needed to improve the current method and develop accurate predictive models. In this research, ten asphalt pavement sites, having various structures, ages, and conditions, were selected in Khuzestan and Kerman provinces in Iran. Field and laboratory testing were performed and the dynamic modulus of in-service asphalt layers was determined. Developed predictive models for dynamic modulus of asphalt mixes including Witczak and Modified Witczak were calibrated and new models were constructed for predicting in-situ dynamic modulus of asphalt layers. These two calibrated models entitled “In-situ Witczak Model” and “In-situ Modified Witczak Model” could be directly used for the prediction of dynamic modulus of in-service asphalt layers from volumetric properties of asphalt mixes and viscosity characteristics of extracted binders without any need for FWD testing. Performance evaluation and validation of new models showed high accuracy and low bias with a very good correlation between predicted and measured values (R2=0.93).

کلیدواژه‌ها [English]

  • Dynamic Modulus of Asphalt Layers
  • FWD
  • Dynamic Modulus Predictive Models
  • Witczak Model
  • Modified Witczak Model
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