【作者】 锁利军；

【导师】 王秉纲；

【作者基本信息】 长安大学 ， 道路与铁道工程， 2008， 博士

【摘要】 沥青路面是我国高等级公路的主要路面型式，沥青路面强度的高低直接影响公路的运营能力和安全舒适性，因此，如何保证或提高沥青混合料的强度至关重要。实践中，沥青路面结构中沥青混合料的真实受力状况为三向应力状态，而Mohr-Coulomb强度理论及其相应的闭式三轴试验都未考虑中间主应力对强度的影响，其表现的应力状态与路面结构中沥青混合料的真实受力状态不符。以往沥青混合料研究对中间主应力分析较少，尤其未提及对沥青混合料强度的贡献。因此，有必要研究中间主应力对沥青混合料强度的影响。在国内外研究成果基础上，对沥青混合料的中间主应力效应进行试验研究。研究表明，沥青混合料强度随中间主应力的增大而增大。在考虑各因素交互作用的条件下，正温、零和负温的正交试验显著性分析得出：中间主应力对沥青混合料的强度有显著影响。因此，对沥青混合料强度研究而言，沥青混合料的中间主应力效应不可忽视。双剪强度理论能考虑中间主应力对材料强度的影响，因此，可选择双剪强度理论分析沥青混合料的强度。针对沥青混合料中间主应力效应试验研究的特点，自行设计制作了平面应变试验装置，确定了沥青混合料试件的形状和尺寸、试件的成型方法、试验温度及加载速率。对不同试验条件下的沥青混合料破坏试件进行对比分析。通过回归分析得到中间主应力方向有侧限，加载速率2mm/min时，温度与强度的关系；通过回归分析得到中间主应力方向有侧限时，-10℃变化到25℃时一组温度下的加载速率与强度的关系。对不同温度、不同加载速率下应力应变曲线进行回归分析，得到中间主应力方向有侧限，加载速率2mm/min时，不同温度下应力应变曲线的表达式。确定了应力应变曲线的两种典型型式。提出了确定沥青混合料弹性极限的具体方法。双剪强度理论的屈服准则可以对应于刚性基层沥青路面面层的剪切破坏模式，可将其应用于沥青路面面层厚度计算中。基于数值计算，建立刚性基层缩缝处沥青路面结构的三维有限元模型，分析刚性基层缩缝处沥青面层的中间主应力以及与之有关的正应力σ₁₂、σ₂₃与主剪应力τ₁₂、τ₂₃，并对不同因素下的三个主剪应力τ₁₂、τ₂₃和τ₁₃以及与其对应地正应力σ₁₂、σ₂₃和σ₁₃进行了排序，为正确使用双剪强度理论公式奠定基础。荷载应力分析表明：因素变化不影响剪应力与正应力的排序；温度应力分析表明：剪应力与正应力的排序具有区间性。依据双剪强度理论，以试验研究结论、力学分析结果为基础，综合考虑以往的研究成果，初步提出基于双剪强度理论的沥青面层厚度分析方法。更多还原

【Abstract】 So far as expressway is concerned, asphalt pavement is one of most typical pavements in China, and highway’s transport capacity、safety and stability depend on asphalt pavement’s quality, which has relevance with strength of asphalt mixture. Because of it, how to improve strength of asphalt mixture is becoming an important problem. In fact, asphalt mixture in asphalt pavement is said to be in a state of triaxial stress, however, both strength theory of Mohr-Coulomb and axisymmetric triaxial testing method do not include intermediate principal stress, actually, it is not accordance with three-dimensional space in asphalt pavement. Especially, there is no report on both intermediate principal stress and intermediate principal stress’s influence on strength in the past research of asphalt mixture. All in all, it is necessary to study intermediate principal stress’s influence on strength of asphalt mixture.Based on the world-wide research, influence of intermediate principal stress on strength of asphalt mixture is studied by testing method. Test study shows that strength of asphalt mixture increases with the increase of intermediate principal stress. When both interaction of different factors and temperature difference are considered, orthogonal experimental design significance analysis shows that intermediate principal stress has an obvious influence on strength of asphalt mixture. Therefore, so far as the research of strength of asphalt mixture is concerned, effect of intermediate principal stress should be taken into account. Actually, effect of intermediate principal stress can be considered in twin shear strength theory, hence, twin shear strength theory should be thought of as strength theory of asphalt mixture.Considering the characteristics of testing method for intermediate principal stress’s influence on strength of asphalt mixture, testing device for plain strain is designed, meanwhile, the size、shape and making method of specimen of asphalt mixture as well as testing condition are decided. Failure specimens of asphalt mixture from different testing conditions are analyzed. When loading velocity is 2mm/min and intermediate principal stress is taken into account, functional relationship between temperature and strength can be obtained. Functional relationship between loading velocity and strength is established through regression method when intermediate principal stress is considered and temperature difference is from -10℃to 25℃. When both different temperature and different loading velocity are considered, regression relationship of stress-strain is studied. Based on that, considering such condition as mtermediate principal stress、2mm/min of loading velocity and temperature difference, function of curve of stress-strain is obtained. Two typical curves of stress-strain are put forward. Meanwhile, concrete method is proposed to determine elastic limit of asphalt mixture.As a matter of fact, failure criterion of twin shear strength theory can be employed to explain surface’s shearing failure of asphalt pavement with rigid base. Consequently, twin shear strength theory should be applied to surface thickness calculation of asphalt pavement with rigid base. Based on numerical calculation, intermediate principal stress、intermediate shear stress and normal stress of asphalt pavement at the location of joint of base are calculated and analyzed by three-dimensional finite element method in this paper. Study of load stress shows that different factor has the same order of shear stress and normal stress; At the same time, study of thermal stress shows that different factor has different order of shear stress and normal stress, meanwhile, order of shear stress and normal stress is changed when the fixed factor has different numerical value. Based on conclusion of both testing study and stress analysis, reviewing the past research results, and combining with twin shear strength theory, method of thickness analysis for asphalt pavement with rigid base is put forward.更多还原