An experimental study of the impact force of debris flows on slit dams

摘要

This study aims to investigate experimentally the impact force of debris flows on slit dams. A site for investigation was selected at Song-Her Village, Taichung, Taiwan. Data on the characteristics of debris flows were recorded using various auto-recording instruments, such as earth pressure gages, load cells, and accelerometers. The grain-size distribution of soil samples for laboratory tests was simulated by use of the equal weight substitution method based on that found in situ. Flume model tests were performed on two types of slit dams. The impact force on the model dams under different flowing conditions and resultant deposition in front of the dam were measured, thereby establishing the relationship between the impact force and the deposited amount of a debris flow. Test results show that the height and the angle of the deposited debris increase with the flume gradient. The vibration and displacement caused by a debris flow to the slit dam with a 90front-face batter are greater than those with a 60front-face batter. Furthermore, the direct impact force exerting on the 90slit dam by a debris flow is found to be greater than that on the 60slit dam. Besides, tires installed in front of the slit are also found to be an effective buffer for absorbing the impact energy of a debris flow.