沥青-集料界面粘脱滑移本构模型及细观粘弹蠕变性能研究

The interface of between aggregate and asphalt is the weaknesses position of the mixture internal structure, which will impose a significant influence on the service life of asphalt mixtures. However, the existing mesomechanics models of asphalt mixtures are almost based on the three-phase composite materials (asphalt mortar, aggregate, void) and have no enough consideration for the actual mechanics characteristics of the weak interface. It is no doubt that the effectiveness of the numerical simulation results will face a great challenge. Based on the self-development load test system, firstly, the project will conduct a research on the influence of different factors, which includes aggregate surface morphology, asphalt type and aging, temperature and loading rate,etc., on the bonding strength of the asphalt-aggregate interface, and then the failure mechanism of the interface bonding strength will be analyzed. Secondly, the objective of the project will establish the constitutive model of the interface bond-slip between aggregate and asphalt. In order to achieve the goal, the stress transfer and debonding process of the interface between asphalt and aggregate will be tested and perceived accurately. As well, the main control parameters of the curve of internal stress and deformation will be extracted. Finally, considering the actual bonding condition of the interface, the mesomechanics finite element analysis models of asphalt mixtures are established to simulate the viscoelastic creep mechanics performance of asphalt mixtures. The simulation results will be calibrated by the laboratory test results. The expected results will provide a theoretical support to perform the mesomechanics analysis of complicated mechanics behavior of asphalt mixtures. The research will have an important academic significance and practical value for the optimization design of asphalt mixtures.

沥青一集料界面是沥青混合料内部结构的薄弱环节，对混合料使用寿命的影响显著。现有沥青混合料各种细观力学分析模型通常是以三相复合材料（沥青胶浆、集料、空隙）为基础，忽略了对于弱界面力学特征的准确表达，从而使细观力学模拟结果的可靠性面临挑战。项目在自主研发数控测试系统的基础上，首先研究不同因素（集料表面形态、沥青类型及老化程度、温度以及加载速率等）对沥青—集料界面粘结强度的影响规律，剖析界面粘结破坏机理；其次控制试验测试条件，定量感知沥青—集料界面的应力传荷及脱粘滑移过程，提取界面“内应力—变形”曲线的主控参数，构建界面粘脱滑移本构模型；最后充分考虑沥青—集料界面实际粘结状态，建立沥青混合料细观力学有限元分析模型，并进行室内试验验证。据此，系统模拟沥青混合料粘弹蠕变力学行为，揭示材料内部参数对粘弹蠕变性能的影响规律。研究成果可为沥青混合料结构的优化设计提供科学依据，具有重要学术意义和实用价值。

沥青混合料是铺面工程材料中最重要的筑路材料，它由集料、沥青和空隙、沥青-集料界面等部分组分，其中沥青-集料界面间的接触是整体结构强度和稳定性最薄弱环节。项目以沥青-集料界面为主要研究对象，首先，在自主研发的沥青-集料界面加载测试系统基础上，采用斜剪和直剪的方式，探讨了集料粗糙度、沥青老化、温度、加载速率集料类型、法向应力等因素对沥青-集料界面粘结强度以及剪切滑移全过程的影响规律，提出了沥青-集料界面性能评价应综合考虑强度指标和能量指标；其次，利用测试系统定量感知了沥青-集料界面的应力传荷与粘脱滑移过程，建立了沥青-集料界面的粘脱滑移本构模型，通过对模型参数与影响因素间的灰色关联度分析表明，老化对于界面模型参数的影响关联度最大，加载速率、温度、法向应力、粗糙度等参数对界面的影响依次减小；再次，通过粘弹性理论和力学试验相结合的方式，构建了沥青-集料界面在压剪耦合状态下的蠕变本构模型，提出了对模型参数的求解方法并对模型有效性进行验证；最后，基于沥青-集料界面粘脱滑移本构模型，建立了考虑界面效应的沥青混合料细观有限元数值模型，开展了小梁蠕变试验数值模拟，并进行室内试验验证，探讨了粗集料级配、棱角特性和弹性模量，空隙率以及沥青-集料界面参数等因素对于沥青混合料蠕变性能的影响规律。研究表明，沥青砂浆-集料界面对于混合料的力学行为影响显著，界面断裂能和粘结强度越大，界面的抗裂性能以及混合料抵抗永久变形能力也越强。中粒式级配沥青混合料蠕变性能优于细粒式沥青混合料，粗集料的棱角性指数越大，沥青混合料抵抗变形的能力越好。在悬浮密实型沥青混合料中，随着空隙率的增大，蠕变变形量逐渐增大，同时空隙率过大容易导致界面开裂。研究成果从细观力学层次上刻画了沥青-集料界面损伤破坏全过程，可为沥青混合料复杂力学行为分析提供理论支持，为细观层次上的沥青混合料的优化设计提供了新思路，具有重要的学术意义和实用价值。