THEORETICAL ANALYSES OF MEASUREMENT OF STRESS-FREE TEMPERATURE IN CONTINUOUS WELDED RAIL

The actual value of the neutral temperature in continuous welded rail is of high concern for track people so as to avoid rail failure in winter and track buckling in summer. The measurement of the rail tension by releasing the rail from sleepers in the section of a certain tens meters and lifting the rail at the center of it has been successfully tried. It is analyzed theoretically with four mechanical models. Results of the analyses make clear that the calculation with the model of the massive beam connected with heavier beams at ends shows excellent coincidence with the practice. With use of the model, the values for another practice, necessary items to be checked, and the optimum conditions in the measurement on Japanese Tokaido Shinkansen are calculated. Through such investigation, not only the characteristics of the measurement are made clear, but it also is confirmed that this measurement is reliable with high precision because only the mechanical characteristics of rail and the weight of track skeleton are concerned. The application of the model to curves is checked.