It is discussed whether the measurement of vibration on stone or rock is useful to evaluate danger of rock-collapse at a slope quantitatively. Therefore the seismic tremors and the seismic noises produced by hammer blows are measured on the boulder stones or the loose parts of rock and then the resistibility of stones or rocks for movement are measured. Then the acceleration ratio, the maximum acceleration value, the r. m. s. value of the acceleration, the frequency spectrum and the transfer function are computed. The acceleration ratio above mentioned is the ratios the acclerations of the boulder stones or the loose parts of rock to that of the slope.
The experimental results indicate the the acceleration ratio of the impulse produced by hammer blows has close relation with the resistibility of the boulder stones or the loose parts of rock and that there exist more obvious relation in the vertieal direction than the horizontal direction.

View full abstract

This report deals with the results of swelling test using the mudstone samples controled to various water potential states, as well as the relation between the dry shrinking of mudstone and the water potential. Moreover, it deals with the simple prediction method of the swelling behavior of mudstone.
The important matters clarified by tests are as follows:
1) Water at pF 4.20-5.50in its potential state accounts for the large amount of water contained in mudstone, and the remarkable shrinking is produced by the dehydration of this water.
2) The amount of swelling recovers almost the amount of shrinking so far as the test sample is not slaked by wetting. In this case, water at the higher pF gives the better swelling efficiency per unit water volume.
3) The occurrences of slaking increase in the drying condition above pF5.50 of test sample before wetting.
4) The minute cracks occurred in the drying process produce a considerable effect on shrinking and swelling behavior of mudstone.
5) It is possible to predict the amount of swelling and the swelling behavior of mudstone by shrinkage ratio at furnace drying.

View full abstract

A few of large scale mudflow occur in mountainous regions a year in Japan, then damage results to roads, buildings and other works of man and affects often people's lives. Hence, in order to get methods of prediction and control of mudflow, various investigations on the phenomena have been carried out.
In this report, many papers of the investigations were collected, and mainly summarized in order to examine the present state of understanding of the phenomena and to advance effective investigations in the future. Following points are deeply concerned, as part (I), which are definition, classification, nature of flowage, deposition and (topographical and geological) conditions of occurrence of mudffow.

View full abstract