关键词: 堆石料； 粗粒含量； 强度劣化； 往复剪切； 抗剪强度

Abstract: The reciprocating shear mechanical properties and strength degradation mechanism of rockfill have important research significance for stability analysis of high fill slopes.A direct shear test was carried out to analyze the shear strength，hysteresis loop area，damping ratio and shear stiffness of soils with different coarse-grained contents and to furtherly explored its degradation mechanism.The test results showed that the shear strength of argillaceous siltstone rockfill was significantly affected by coarse grain content and reciprocating shear times.The shear strength increased with the increasing of coarse grain content and decreased with the reciprocating shear times.The area of hysteresis loop was positively correlated with coarse grain content and negatively correlated with the numbers of reciprocating shear.The damping ratio had nothing to do with the coarse grain content，but it decreased with the increasing of the numbers of reciprocating shear.The exponential relationship between shear stiffness of soil failure and the coarse grain content was significant，and the normalized shear stiffness was linearly correlated with the numbers of reciprocating shears.Based on this，an empirical formula of shear stiffness of argillaceous siltstone rockfill considering different coarse grain content and reciprocating shear times was established，which can provide a calculation basis for the stability analysis of accumulation bodies.

Key words: rockfill material； coarse grain content； strength deterioration； reciprocating direct shear； shear strength