For the purpose of forecasting the frost heaving of rock masses, the author studied on the relation between the rate of frost heaving and physical properties of rocks such as grain size distribution, specific gravity, water contents, etc. Laboratory tests were carried out to rock specimens which are molded into a cylinder with the height of 3 cm and the diameter of 8 cm, or rock fragments packed in the same scale cylindrical case.
These pieces were put in -3°C air for 6 days, and the expansion of height was measured at each pieces. As results, the following facts are pointed out throughout the tests for 123 specimens and 55 cases, namely:
. 1) frost heaving is most remarkable in soft and fine-grained sedimentary rocks such as middle -upper Neogene mudstone and tuffaceous rocks.
2) frost heaving is generally found among the rocks which are less than 0.2 in specific gravity or more than 20% in water contents.
3) degree of frost heaving is markedly increased for weathered or sheared masses of above-mentioned sedimentary rocks.