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针对现有沥青混合料剪切试验方法的不足,对国内外沥青混合料抗剪性能试验方法进行研究分析,提出了一种新的正应力条件下的扭转剪切试验方法。其原理是通过千斤顶对试件均匀施加正应力,同时再通过齿条和齿轮将竖向力转化成扭矩,使圆柱体沥青混合料试件处于压剪状态。建立三维有限元模型进行理论分析,得出试件内部的剪应力分布,表明试件破坏状态为剪切破坏。对两种沥青混合料在不同温度和不同正应力条件下进行扭转剪切试验,结果表明混合料的抗剪强度随着温度的升高急剧降低,混合料的抗剪强度与正应力呈线性增长关系,符合摩尔-库伦强度理论。根据摩尔-库伦理论线性回归得到混合料的黏聚力和内摩擦角,将其与其他3种试验方法结果进行比较,表明该试验方法具有较好的可行性和可靠性,可以有效地评价沥青混合料剪切性能。
Aimed at the deficiency of existing shear test methods of asphalt mixture, the test methods of shear resistance of asphalt mixtures at home and abroad are studied and analyzed. A new torsional shear test method under normal stress conditions is proposed. The principle is through the jack uniform stress applied to the specimen, and then through the rack and gear vertical force into torque, so that the cylinder asphalt mixture specimen in the state of pressure and shear. The establishment of three-dimensional finite element model for theoretical analysis, obtained within the specimen shear stress distribution, indicating that the specimen failure state is shear failure. The torsional shear tests of two kinds of asphalt mixture under different temperatures and different normal stresses show that the shear strength of the mixture decreases sharply with the increase of temperature and the shear strength and normal stress of the mixture increase linearly Relationship, in line with the Moore-Coulomb strength theory. According to the linear regression of Mohr-Coulomb theory, the cohesion and internal friction angle of the mixture were obtained and compared with the results of the other three kinds of test methods, indicating that the test method has good feasibility and reliability, can effectively evaluate the asphalt Mixture shear properties.