RAIL TRACK FORMATIONS FOR HIGHER AXLE LOADS AND SPEEDS

Abstract

Rail network system forms an integral part of the transportation system in a country and plays a significant role in sustaining healthy economy. With the increase in population and demand for goods to transport from one place to another puts an additional pressure over the existing rail network. Thus, the demand for high speeds and higher axle load trains is increasing. Higher speeds and loads call for more settlement and stresses in the existing track system. Hence, it is impossible to run high speed trains on the existing track. To do so, it is required to change the track formation so that both the settlements and stresses are reduced to permissible limits. To find the settlements and dynamic stresses, a detailed parametric study has been carried out in Finite Element Modelling software PLAXIS-3D. To carry out with the work the behaviour of all the components were studied. Based on the different failure criteria various component of track super and sub-structure has been assigned with different material models. A standard geometrical rail track formation is analyzed for various sub soil subgrade conditions as per defined by the Indian Railways standards. Dynamic analysis has been carried out for one standard axle load and one higher axle load at various speeds. Results for deformations and stresses have been studied and presented in the form of charts and graphs. The effect of inclusion of geogrid of at the interface of ballast and sub ballast has been also analyzed. By placing the geogrid, a significant reduction in deformations were observed and also the increase in bearing capacity of the sub structure components of the track are registered.