Debris flow is one of the types of landslides, and occur mainly in mountain channel parts that have steep slopes due to extreme rainfall. Recently, due to climate change, rainfall has increased, and the frequency of debris flow has increased. In addition, the risk of damage by debris is increasing due to continuous population growth and indiscriminate development. In particular, in the case of densely populated areas adjacent to mountainous areas such as Umyeon Mt. in Seoul and Hwangnyeong Mt. in Busan, it is necessary to clearly characterize the behavior of the debris flow. Because it can cause not only economic damage but also huge human damage. Therefore, in this study, it was conducted on the behavioral characteristics of the debris flow according to the rheological properties and the performance evaluation of the net-type barrier to reduce the behavior of debris flow. The research progress is as follows.
First, rheological experiment were conducted using the developed large scale vane-type rheometer test equipment. In the test, viscosity and yield stresses were calculated using natural soils and the water content was converted to volumetric sediment concentration. Viscosity and yield stress increased with increasing volumetric sediment concentration(Cv) and were similar at the different range of volumetric sediment concentration(Cv) according to the clay fraction of each sample.
Second, to analyze the behavioral characteristics of the debris flow according to the rheological properties, a small scale debris flow experiment equipment was manufactured. For each sample, experiments were conducted under various water content conditions. Through experiments, the front velocity and the deposition (runout distance and deposition volume) of debris flow were calculated. In both samples, as the Cv decreased, the front velocity and the deposition increased. In the sample with high clay fraction, the rate of the front velocity and the deposition increase were higher. In addition, both samples showed that the front velocity and the deposition of the debris flow were increased as the rheological properties decreased. According to the change of rheological properties, a sample with high clay fraction had a greater rate of change in the front velocity and the deposition.
Third, net-type barrier were fabricated and installed on small scale flume experiment equipment to carry out performance evaluation experiments of net-type barrier. The bigger the mesh size of the net-type barrier and the higher water content, the lower the reduction rate of the front velocity and the deposition.
The result of this study is expected to be able to use as the important basic data for predicting the behavioral characteristics in case of occurrence of debris flow and analyzing the effect of reducing debris flow behavior through the installation of net-type barrier.