An Experimental Study on Railway Ballast Degradation Under Cyclic Loading

To investigate the degradation of railway track ballast layer, triaxial tests, full-scale railways test facilities or models of a section can be used. In this study, a half-section scaled model of a ballasted track consisting of a steel sleeper and a metal box filled with aggregates was developed. The impact of cyclic loading on the ballast degradation was investigated using the experimental model considering ballast rearrangement and breakage. The frequency of the cyclic loading was set to 8 Hz, which mimics a train passage with an axle wheel spacing of 2.6 m and a speed of 70 km/h. MakAdam aggregates from Skutskar quarry in Sweden were used in the tests. The size of the ballast aggregates was scaled down by the parallel-gradation scaling technique. The results demonstrate that vertical ballast deformation exhibited an exponential trend at the beginning of the cyclic loading followed by a linear trend. The ballast aggregates mainly broke at their corners rather than in the middle after 100,000 loading cycles.