Repeated One-Dimensional Freeze-Thaw Experiments on Sapporo Soft Rock

In this research the behavior of Sapporo soft rock was investigated under the effect of repeated one-dimensional freeze-thaw. As indicators of the rate of deterioration, the AE (Acoustic Emissions) , porosity, and elastic wave velocity under dry conditions were used. It is considered that the microscopic destruction that occurred inside Sapporo soft rock, which doesn't show significant effect of freezing, can be analyzed in detail by measuring the AE.Main results obtained in our research are summarized as follows:(1) No deterioration of the test pieces was apparently observed even after 40 cycles of one-dimensional freeze-thaw. This experimental result implies that the effects of one-dimensional freezing on rock are significantly different from those resulting from three-dimensional freezing.(2) It was observed that the total number of occurrences of AE was the highest in the first cycle of freeze-thaw, and decreased thereafter. However, the number was converging to an almost constant value.(3) It was confirmed that the number of occurrences of AE decreased during freezing (processes 1, 2, and 3) after several freeze-thaw cycles, but increased during thawing (process 4) .(4) It was confirmed that the displacement of expansion during freezing and shrinking during thawing increased with repetition of the freeze-thaw cycle. The increase in the number of occurrences of AE during thawing mentioned above was due to this increase in the displacement of shrinking during thawing.The mechanism of deterioration caused by one-dimensional freeze-thaw on Sapporo soft rock revealed in this research is of great value in engineering for the examination of methods for the maintenance of architecture made of Sapporo soft rock, which is currently being re-evaluated as historical architecture.