| Budget Amount *help |
¥3,000,000 (Direct Cost: ¥3,000,000)
Fiscal Year 2005: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 2004: ¥2,500,000 (Direct Cost: ¥2,500,000)
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| Research Abstract |
To understand the mechanism of track deterioration and predict track settlement or track irregularity growth, for reducing track maintenance cost and designing new track structures, this research describes numerical discontinuous model studies of railroad ballast with regard to ballasted track deterioration using discontinuous deformation analysis. After reviewing a present research status and future issues on prediction of track settlement with track dynamic model, this research first present a newly developed measuring system of grain shapes by using a 3D digitizer and newly developed 2D and 3D numerical modeling techniques using exact shapes and dimensions of real ballast stones. Then it describes analysis of dynamic behavior of railroad ballasts in response to dynamic sinusoidal loads. The model comprises an assemblage of arbitrarily shaped two-dimensional polygonal crushed stones, rails, sleepers, and a roadbed. Dependencies of particle activities in a narrow area of railroad track on frequency and acceleration were evaluated with such parameters as: increase in void volume (dilation); and horizontal, vertical, rotational displacements, and kinetic energy of ballast grains. Next, a new embedding type sensing-stone apparatus than can measure dynamic 3-D rigid body displacements and rotational behaviors of internal ballast grains of the track was developed with using Piezoresistive-type thinnest semiconductor triaxial accelerating sensors that can simultaneously detect acceleration in three axial directions (X, Y and Z) with a single chip. It confirmed that the newly developed apparatus and techniques are very beneficial.
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