飽和含水状態にある岩石の繰り返し疲労特性におよぼす間隙水圧の影響

封圧下において繰り返し圧縮荷重を受ける岩石の力学的挙動に関する研究 (第2報)

抄録

In order to clarify the effect of pore pressure on cyclic fatigue characteristics of water saturated rocks under confining pressure, cyclic fatigue tests using 1 Hz sinusoidal wave of pulsating compressive stress were carried out under both confining pressure and pore pressure for Kimachi sandstone and Hirono sandy mudstone laying emphasis on endurance limit and the change of volumetric strain in cyclic fatigue process.
Main results obtained in this study were summarized as follows.
(1) Under the condition of constant pore pressure and constant confining pressure, endurance limit exists for both rocks. Pore pressure remarkably decreases both number of cycles to failure and endurance limit.
(2) Stress ratio corresponding to endurance limit increases with b value in equation (1), which means that the lower the stress ratio corresponding to endurance limit is, the more number of cycles is required to reach the endurance limit.
(3) Pore pressure promotes dilatancy in fatigue process of water saturated rocks, and the dilatancy due to the pore pressure lowers endurance limit and the number of cycles to failure.