岩石の疲労寿命の分布特性とS-N線図

岩石の疲労破壊に関する研究 (第1報)

抄録

In this paper, the fatigue failure of some rocks under the repeated compressive load is discussed from the point of view that the fatigue failure is a stochastic process. Using a graphical method in which the logarithms of the probability of survival are plotted against the fatigue lives, it is revealed that the probability of survival is represented with the sum of two expotential functions, i. e.
p=ξ1·exp (-λ₁·N) +ξ₂·exp (-λ₂·N) where p: the probability of survivalξ_i: the probability that the failure of test piece occurs by the fracture mechamism with the rate constamtλ_i N: the number of loading cycles
This result means that the fatigue failure of rocks consists of two exclusive Poisson's processes of 1st order, each of which would correspond to the inter- and innergranular fracture of the mineral particles constituting the rock.
In order to obtain the S-N curve, the effect of the stress amplitude on the rate constant of the fatigue failure is investigated. A series of experiments is carried out at a constant minimum load and several levels of maximum loads.
Finnally, it is indicated that the loading frequency has a little effect on the fatigue life of the rock.