Cyclic filtration apparatus for testing subballast under rail track

An apparatus capable of testing subballast-subgrade filtration behavior under cyclic loading is presented. The apparatus can be used to accurately monitor the pressure fluctuations, permeability of the filtration system, and turbidity variations of the effluent with time. The test results show that the frequency of cyclic loading has an influence on the filtration behavior of subballast material used in railway tracks. Further, the effect of cyclic load on the design and selection of subballast materials over a wet subgrade must be considered to avoid filter malfunctioning.