Subballast compaction in track rehabilitation by means of plate compactors

Abstract

In the course of track maintenance, formation rehabilitation machines like Plasser & Theurer´s AHM 800-R are widely used for the renewal of the formation protective layer (FPL). Two excavating chains remove the existing ballast and FPL. Using integrated ballast washing plants, crushing plants and mixers, large quantities of the old ballast can be reconditioned and used for the FPL, which is automatically filled and compacted by a set of six plate compactors. The final FPL usually has a thickness of 40 cm, which results in a challenge for the plate compactors since the compactors are limited in size and weight to be able to operate below the raised track grid. The ability of the plate compactors to sufficiently compact the FPL is investigated by means of a mechanical model describing the interaction of the compactor with the soil. Three operating phases - loading, unloading and loss of contact - characterize the interaction and are simulated for numerous parameter combinations of compactor and soil characteristics. The motion quantities obtained from the model are evaluated and discussed. The results of modeling show that an increase of the FPL stiffness is accompanied by a significant change of the motion behavior.