Abstract: Due to the long-term landing and take-off of aircraft, the development characteristics of the cumulative plastic strain of silt foundation will change. The influences of loading frequency and degree of compaction on the long-term cumulative plastic deformation of compacted silt under different dynamic stress amplitudes were studied based on dynamic triaxial test. The test results show that the cumulative plastic strain evolution type of compacted silt under different cyclic stress ratios can be divided into three types: plastic shakedown, plastic creep and incremental failure. In addition, the degree of compaction affects the cumulative plastic strain and the ratio of critical cyclic dynamic stress. And the loading frequency has a significant influence on the increase rate of cumulative deformation in the early stage of loading. In addition, the elastic behavior is obviously influenced by the degree of compaction, with the dynamic modulus increasing with the increase of compactness. Based on that the evolution characteristics of cumulative plastic strain of compacted silt showing a stable type, a model of cumulative plastic strain of compacted silt was proposed, in which the influences of degree of compaction and loading frequency were considered. It was found that the fitting parameters had a good linear relationship with the cyclic stress ratio under the same degree of compaction and loading frequency during model parameter fitting. Based on the analysis of the correlation among the parameters, the relationships between these parameters and cyclic stress ratio, degree of compaction and loading frequency were determined.

Key words: compacted silt, dynamic triaxial test, cyclic stress ratio, degree of compaction, loading frequency, cumulative plastic strain model