Very long-term loading of roof beams in limestone caves

Fixed-end beams in limestone caves exhibit very large deflections that result from tensile crack propagation followed by compressive failure. Two different models for time dependence of compressive strength based on subcritical crack propagation yield nearly identical results and are effectively independent of initial flaw size. These models are consistent with compressive failure in the cave beams, and observed deflections suggest that this compressive failure is by splitting, causing delamination of the beams.