复杂应力状态下沥青混合料强度统一计算方法研究

In our country, maximum tensile stress theory used in asphalt pavement design can not consider the synergistic damage effect among each stress component. And may lead to early damage of pavement structure. . In order to study strength properties and failure modes of asphalt mixture under simple and complex stress states（especially at the conditions that the stress states are similar to pavement structure, such as triaxial compression and triaxial tension and compression stress states）, uniaxial strength tests, including compression, tension, bending , splitting tests, and self-developed triaxial strength tests are systematically carried out in this project. On this basis, the unified strength model and failure criterion for one-dimensional and three-dimensional stress states are established. And the law for strength characteristics and strength envelop change with temperature, loading rate and hydrostatic stress and other factors are revealed. Then, based on the unified analysis of ultimate strength at various test conditions and stress states, the strength unified calculation method of asphalt mixture is proposed, and provide theoretical basis for resistance calculation of asphalt pavement structure. Finally, the load checking method of asphalt pavement is proposed, and the destruction source is determined through the study of mechanics analysis and loading check for typical pavement structure. Besides, the load control index and standard for asphalt layer are proposed.. This research provides the test and theoretical reference for material and structure design of asphalt pavement under three dimensional stress states, and can promote the progress and development of the design theory and method for asphalt pavement in our country.

我国沥青路面设计采用的最大拉应力理论无法考虑各应力分量之间的协同破坏作用，可能导致路面的早期损坏。. 为此，项目拟通过系统的拉、压、弯、劈裂试验及自主创新的三轴试验装置及方法，研究简单及复杂应力状态下(特别是与路面结构应力状态相近的三向压缩及三向拉压应力状态)沥青混合料的强度特性及破坏模式，统一建立一维与三维强度模型及破坏准则，揭示沥青混合料强度特性及强度包络图随温度、加载速度、静水应力等因素的变化规律。在此基础上，对不同试验条件与应力状态的极限强度值进行统一分析，提出复杂应力状态下的强度统一计算方法，为沥青路面结构抗力计算提供理论依据。最后，提出沥青路面荷载校核方法，对典型路面结构进行力学分析及荷载校核，确定路面结构的破坏源，提出沥青层荷载控制指标与标准。. 研究成果为沥青路面结构按三维复杂应力状态进行设计提供了试验及理论参考，能够推动我国沥青路面设计理论与方法的进步与发展。

针对沥青路面设计采用的最大拉应力破坏准则无法考虑各应力分量之间协同破坏作用的问题，本项目自主创新了三轴试验装置及方法，系统地开展了AC-13沥青混合料的三轴试验；揭示了复杂应力状态下，特别是与路面结构应力状态相近的三向压缩及三轴拉压应力状态下沥青混合料的强度特性，将混合料的破坏模式划分为拉应力、拉应变、斜剪破坏等类型。.基于三轴试验结果建立了非线性的八面体强度模型与破坏准则，揭示了沥青混合料强度包络面随温度、加载速度、静水应力等的变化规律。并在应力状态与路面结构相近的条件下，简化了三维强度模型及其试验方法，提出了工程应用强度模型及参数获取方法。在此基础上，建立了复杂应力状态下的强度统一计算方法，统一了一维与三维强度参数，并通过传统的拉、压、弯、劈裂试验对强度模型的科学性进行了验证。最后，提出了沥青路面荷载校核方法，通过对路面结构进行力学分析及荷载校核，确定了沥青面层的破坏源，提出了AC-13沥青层的荷载控制指标与标准。.这种研究方法既可应用于沥青混合料，也适用于半刚性基层材料，为沥青路面结构按三维复杂应力状态进行设计提供了试验及理论参考，能够推动我国沥青路面设计理论与方法的进步。

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