ANALYSIS OF INFINITE BEAMS ON TENSIONLESS REINFORCED EARTH BEDS UNDER MOVING LOADS

Abstract

Usually, rails are modeled as infinite beams in the analysis and design of railroad tracks. There are many factors like load intensity, velocity of load, damping of soil — rail system, other geometrical parameters, which play an important role in the analysis. Further, due to scarcity of land with good bearing capacity, construction is being carried on improved. ground. This can be by means of stone columns or geosynthetics etc. In this work, an attempt has been made to model and analyze the rails (idealized as infinite beams), lying on reinforced earth beds, and subjected to moving load. Earth beds have been assumed to react only under compression, i.e., act as tensionless foundation. Geosynthetic has been used to reinforce the poor earth beds and modeled as an elastic membrane. Governing differential equations for the rail — foundation system have been obtained and finite difference method has been adopted for solving these by means of Gauss — Siedel iterative scheme. A detailed parametric study has been conducted to study the effect of applied load, velocity of the load, relative compressibility of soil layers on the response of the rail — foundation system. The value of input parameters like applied load intensity, velocity of applied load, properties of soil subgrade etc. have been adopted as per the Indian railway conditions. It has been found that applied load intensity, velocity of moving load has a significant influence on the response of rails. Damping has not been found to have significant effect on the response due to tensionless nature of the foundation system.