レールが軸力を受けている無限軌道を対象に波動分散解析を行った. 解析では, レールとまくらぎを3次元Timoshenkoはり要素により離散化し, 水平・鉛直たわみと振り振動の影響を再現した. まくらぎ1区間で与えられる軌きょう1ユニットの運動方程式にFloquet原理を適用し, 無限軌道内を伝播する波動モードの分散特性を求めた. 解析結果に基づき, 軸力に鋭敏な振動モードや, 締結装置の剛性などが共振周波数に及ぼす影響などについて考察した.Wave modes propagating in rails subjected to an axial load due to temperature stress are analyzed. An infinite track consisting of rails and sleepers is modeled by 3-D Timoshenko beams. The Floquet theorem is applied to the equation of motion of track sub-structure given by a repetitive unit. The wave dispersion analysis is then reduced to an eigenvalue problem in terms of the axial load, the wave number and the frequency. Sensitivity of axial loads to the wave number and frequency is investigated in the context of the dispersion analysis. Through those analyses, modes which are suitable for evaluation of axial load and the influence of uncertainties in track modeling on these modes are discussed.