Development of a New Mechanistic Empirical Rutting Model for Unbound Granular Material
Development of a New Mechanistic Empirical Rutting Model for Unbound Granular Material
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DOI：
10.1061/(asce)mt.1943-5533.0001555
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发表时间：
2016-08-01
影响因子：
3.2
通讯作者：
Lytton, Robert L.
中科院分区：
文献类型：
--
作者：
Gu, Fan;Zhang, Yuqing;Lytton, Robert L.
提出了一种新的力学-经验车辙模型来评价非结合粒料的永久变形特性。为了表征UGM中车辙行为的应力依赖性，MER模型将软化应力项和硬化应力项并入基于Drucker-Prager塑性屈服准则的Tseng-Lytton模型。对两种类型的UGM进行了重复加载三轴试验，采用7种应力状态对模型系数进行了标定，采用2种应力状态对模型预测的准确性进行了验证。根据三轴试验结果，建立了这两个合并应力项与累积永久应变的相关性。结果发现，相关性符合幂函数，R2值为0.97-0.99。将MER模型与现有的UGM车辙模型（包括MEPDG模型、Korkiala-Tanttu模型和UIUC模型）进行了对比，分析了试验室实测和模型预测的车辙偏差。与现有的UGM车辙模型相比，MER模型能够更好地描述UGM在不同应力状态下的应力相关车辙行为。此外，MER模型的预测精度明显高于现有模型。还进行了敏感性分析，以评估的影响，凝聚力和摩擦角的PD行为。这证明了MER模型表征UGM车辙行为的水分敏感性的潜力。最后，将MER模型应用于非线性有限元程序中，预测了柔性路面的车辙深度。与MEPDG模型相比，MER模型预测的基层车辙深度更高，对荷载大小和基层模量的变化更敏感。
This paper proposes a new mechanistic-empirical rutting (MER) model to evaluate the permanent deformation (PD) behavior of unbound granular material (UGM). To characterize the stress dependence of rutting behavior in UGM, the MER model incorporated a softening stress term and a hardening stress term into the Tseng-Lytton model, which is based on the Drucker-Prager plastic yield criterion. Repeated load triaxial tests were performed on two types of UGMs in this study, employing seven stress states to calibrate the model coefficients, and two stress states to validate the accuracy of the model predictions. The correlations of the two incorporated stress terms with the accumulated permanent strains were established based on the triaxial test results. It was found that the correlations are fitted by power functions with 0.97-0.99 R2 values. The proposed MER model was compared with the existing UGM rutting models, including the MEPDG model, Korkiala-Tanttu model, and UIUC model in terms of differences between the laboratory-measured and model-predicted PDs. Compared to the existing UGM rutting models, the MER model is better able to characterize the stress-dependent rutting behavior of UGM at various stress states. In addition, the prediction accuracy of the MER model is significantly higher than the existing models. A sensitivity analysis was also performed to evaluate the effects of cohesion and friction angle on the PD behavior. This demonstrates the potential of the MER model to characterize the moisture sensitivity of rutting behavior for the UGM. Finally, the MER model was implemented in a nonlinear finite element program to predict the rut depth of a flexible pavement. Compared to the MEPDG model, the MER model always predicts higher rut depths of the base layer and is more sensitive than the MEPDG model to the variations of load magnitude and base modulus.