基于边界效应理论的沥青混合料强度参数研究

Research on strength parameters of asphalt mixture based on boundary effect theory

为了研究沥青混合料的强度参数和断裂性能,在边界效应理论基础上,预制切口偏中距离的影响,引入等效峰值载荷换算公式,得到了一种改进边界效应模型。在5℃的条件下开展了不同偏中距离的三点弯曲试件AC-13级配沥青混合料断裂试验,采用扩展有限元法对同样尺寸的三点弯曲试件进行了模拟,通过载荷位移曲线验证了数值模型的可靠性。将试验与数值模拟获得的峰值载荷代入到改进模型推导了沥青混合料的抗拉强度和断裂韧度,最后利用模型结果反演拟合得到偏中距离对峰值载荷的影响曲线。结果表明,本研究模型推导和反演结果均与试验结果接近,证明改进边界效应模型不仅克服了原有模型无法应用在复合型断裂试件的局限性,还为沥青混合料的弹脆性断裂性能确定提供了一种预测方法。

To analyze the strength parameters and fracture characteristics of the asphalt mixture,after the offset distance was considered and an equivalent peak load was introduced,a modified boundary effect model was established based on the boundary effect(BE)theory.The different pre-crack three-point bending tests were carried out at 5℃,and the corresponding XFEM modeling was performed and validated by the load displacement curve from the tests.The tensile strength and fracture toughness were determined by the load peak obtained from test and numerical simulation.Finally the variation curve between the offset distance and load peak was inversed and fitted by the modified model solution.The results show there is little difference between the model solution and test data.It is proved that a modified boundary effect model not only overcomes the limitation of mixed fracture specimens application of the original BE model,but also provides a prediction method for determining the elastic and brittle fracture performance of asphalt mixtures.