基于尺寸效应的非标准试件抗拉强度影响规律研究

Study on the Tensile Strength of the Test Piece Based on Non-Standard Size Effect

目的研究不同试件尺寸对沥青混合料试件抗拉性能及冻融劈裂抗拉强度比的影响规律,测量路面非标准芯样力学性能。方法采用AC-13、AC-16两种级配类型、设计不同高度的试件进行常温劈裂及冻融劈裂试验,并现场钻取路面芯样进行试验,验证尺寸效应系数公式的准确性。结果当试件高为30~63.5 mm时,不同级配试件抗拉强度与冻融劈裂抗拉强度比均随着高度的增大而增大;空隙率对不同高度试件抗拉强度平均值影响较小;抗拉强度与冻融劈裂抗拉强度比尺寸效应系数均随着高度增大而减小;路面钻取芯样试验结果转换后数值离散型较小。结论沥青混合料试件具有尺寸效应,笔者提出了尺寸效应系数转换公式,并验证了小尺寸试件进行抗拉性能检测的可靠性,可以实现标准试件与非标准试件之间的强度转换。

In order to accurately measure the mechanical properties of pavement non-standard core samples,the effects of different test specimen sizes on the tensile properties of asphalt mixture and the tensile strength ratio of freeze-thaw splitting were studied.This paper uses AC-13,AC-16 two gradation types,design different height of test specimens for normal temperature cracking and freeze-thaw cracking tests,and on-site drilling core samples for testing and verify the accuracy of the size effect coefficient formula.The results show that,when the height of the specimens is between 30 mm and 63.5 mm,the ratio of tensile strength to freeze-thaw splitting tensile strength of the specimens with different levels of mixture increases with the increase of height;The void fraction has little effect on the average tensile strength of specimens with different heights;Both the effect coefficient and the freeze-thaw splitting tensile strength ratio size effect coefficient decrease with increasing height;The sample test results of road drilling have a smaller discrete value after conversion.It is proved that the asphalt mixture specimen has a size effect,and the reliability of the tensile performance test using a small specimen is verified,and the strength conversion between the standard specimen and the non-standard specimen is realized.