沥青混合料永久变形的三轴重复荷载试验方法

Triaxial Repeated Load Test Method for Permanent Deformation of Asphalt Mixture

对沥青混合料永久变形的三轴重复荷载试验方法进行了研究,提出了完整的试件制备方法、试验设备要求以及试验的边界条件、温度条件和荷载条件等试验参数.对芯样空隙率与原样试件空隙率的转换关系进行了研究,结果表明:放大原样试件的空隙率,可以保证芯样的空隙率满足要求.对沥青混合料流变数的确定方法进行了研究,提出了采用三次样条插值函数分段拟合永久应变-荷载作用次数的关系曲线,分析了永久应变速率的变化规律,并以此确定了沥青混合料的流变数.重点研究了温度和荷载应力对沥青混合料流变数的影响,确定了最佳试验温度(45℃)和轴向应力(700 kPa).最后,对试验方法的重复性和再现性进行了分析,确认该方法精度高,可以作为沥青混合料抗永久变形能力评判的标准试验方法.

Triaxial repeated load test method for permanent deformation of asphalt mixture was researched, and the preparation method of test specimen as well as apparatus requirement, boundary condition, temperature eonditions and loading conditions were put forward. Conversion relationship between voids in core specimen and original specimen is obtained, and it is suggested that voids in original specimen should be enlarged to ensure voids in core specimen so as to meet expected requirements. The piecewise cubic spline interpolation function is adopted to fit the relation curve between permanent strains and loading cycles, and the permanent strain rate is analyzed to determine the flow number. Then the influenee of temperature and axial pressure on flow number was studied, and recommended axial pressure was 700 kPa while recommended test temperature was 45℃. Finally, repeatability and reproducibility of the test method were analyzed. It is indicated that this test method has a good precision, and it can be used to estimate the rut resistance of asphalt mixture as a standard test.