Experimental study on damping ratio and dissipated energy characteristics of silt under intermittent cyclic loading
There exist following time intervals between trains traveling in the same direction on the track.Therefore,the time-dependent curve of the dynamic train load carried by the roadbed consists of the time-dependent curve of the dynamic load during the passage of the train and the tracking time interval during which the dynamic load is zero.In order to study the effect of intermittent loading on dynamic characteristics of heavy railway embankment,a series of dynamic triaxial tests on silt considering continuous cyclic loading and cyclic loading with intermittent intervals was conducted.The variation rules of specimen dissipated energy and damping ratio under the two loading modes were comparatively analyzed under different water content,enclosing pressure and stress states.The results indicate that:the cumulative plastic strain at each loading stage of the specimen under intermittent loading decreases with increasing number of loading stages,and the rate of cumulative plastic strain decreases accordingly.In contrast,under continuous loading,the hysteresis loop of the specimen gradually becomes denser in the early stage of loading but loosens in the later stages with increasing vibration cycles.The damping ratio of the silt increases with increasing water content.The increase of the perimeter pressure reduces the magnitude of the variation of the damping ratio,and the intermittent action decreases its damping ratio.Combined with the research results of cumulative plastic strain of the specimen,the boundary of dissipated energy of the specimen was divided,and the method of judging the dynamic stability of roadbed from the perspective of energy dissipation was proposed.First,when the relative dissipated energy eigenvalue is lower than 24%,the specimen is in a dynamically stabilized state.Second,when the relative dissipated energy eigenvalue is in the range of 24%～68%,the specimen is in a critical state.Lastly,when the relative dissipated energy eigenvalue is more than 68%,the specimen is in an unstable state.The results of the study provide a reference for further optimizing the railroad embankment maintenance and design of the railroad.
siltintermittent cyclic loadingdamping ratiodissipated energythe relative dissipated energy eigenvalue
万方数据
维普
