土砂堆積形状と堆積空間

抄録

We investigated the actual conditions of heavy rain disasters which occurred on August 1981 at Hidaka and Mt. Yohtei in Hokkaido, and studied the deposit shapes formed by debris flows and landslides, partially with some laboratory experiments.
The results are as follows:
1) The plane shape of deposit was expressed by the length, width and angle of dispersion (Fig. 3, Table 1).
2) It was considered that the deposit shape was influenced by the channel plane shape (Fig. 7. 8).
3) Comparing the results of actual investigations and experiments, it was clarified that the deposit shape was more influenced by the channel plane shape than by the channel longitudinal one (Fig. 9, 11, 12).
4) The values of angle of dispersion (tan θ) were 0.36-2.90 in Hidaka, 0.20-0.73 in experiments and 0.11-1.07 in Shodoshima. The values of the ratio of deposit width to length (Bd/L) were calculated at 0.20-1.23 in Hidaka, 0.12-0.53 in experiments and 0.11-0.56 in Shodoshima.
5) The model of deposit shape was expressed by Bd/L and tan θ in Fig. 13, and was formulated in the following equation:
log (Bd/L)=0.690 log (tan θ)-0.165
6) We discussed the length and area of deposit by the scale and form of movement, and the effects of retardation works to the debris flows which had occurred in the Aokinosawa River at Mt. Yohtei (Fig. 14, 15).
7) Some effects of retardation works were recognized and the planning method was discussed with regard to the effects (Fig. 16, 17).