抄録
On the basis of laboratory creep test of rocks under uniaxial compressive load, it is revealed that the strain rate of rock sample is inversely proportional to the residual failure life in the tertiary creep region. The residual failure life is defined as the time remained from an arbitrary time up to the time when creep failure occurs. Hence, the residual failure life is independent of the starting point of either time measurement or loading. The strain rate is also independent of the starting point of time measurement according to the definition.
It means that if the strain rate is observed from an arbitrary time in the tertiary creep region, then the residual failure life could be estimated.
This law of tertiary creep strain rate is applied to estimate the residual failure life of pillar which is loaded by approximately uniaxial compressive load.
Firstly, the estimation procedure of residual failure life of pillar is proposed and discussed by means of an example which is taken out from results of laboratory creep test of a rock. Secondly, the accuracy of estimation of residual failure life is discussed on the basis of theory of mathematical statistics.
It is revealed that
(1) the effect of sample number on the accuracy of estimation is not remarkable;
(2) as increases the term of observation, remarkably decreases the error of estimation. However, from the technical point of view, it is recommended to estimate the residual failure life as early as possible by several data taken in short term of observation, at the cost of accuracy, in order to ensure sufficient time for possible remedies.
