TRACK DEFLECTIONS AND MACROSCOPIC MOVEMENT OF RAILWAY EMBANKMENT

Measurements were made under traffic of track deflections and of movem ent in the ground beneath railway track at an embankment which suffere d chronically from rapidly deteriorating track geometry and from the n eed frequently to deposit ballast on the track. The deflections so mea sured were at least one order of magnitude greater than those which wo uld be common on a railway, and similarly exceeded common standards of vertical line and level by an order of magnitude. These large deflect ions arose hugely from movement in a 1-1.5m deep layer of ash, giving rise to an effective track modulus of the order of 1MPa. This is very much less than typical values, which am in the range 30-300 MPa; the l owest value reported to date in the literature is about 8MPa. In order satisfactorily to treat both fundamental problems it would be necessa ry to stop movement in the ash, either by removing it completely or by stabilising it with concrete or the like.