Routing Debris Flow with Limestone

Abstract

本研究は石灰質による流下土石流と土石流扇状地の形成過程を宇治川オープンラボラトリに設置された急勾配水路を用いて解析を行なったものであり、土石流発生と発達過程における分級および、扇状地における粒度分布解析結果を明らかにするものである。本研究においては混合粒径土石流の分級を議論する基礎実験として二つの異なる流径(2.5mmと6mm)を用いた土石流扇状地の形成実験と高速ビデオカメラを用いた粒子追跡を行なった。扇状地の形成過程の初期段階において荒い流径粒子が前方に集中し、これらが扇状地の発達に影響を与える事を明らかにした。

In the recent decade, several debris flow events have occurred and caused hundreds of deaths, injured people and damaged many facilities. Consequently, there is a strong need to devise a method to evaluate the possible debris flow hazard areas. To comprehend precisely this problem, this study sets up debris flow experimental channel at Ujigawa Open Laboratory. The model apparatus are consisted with three main components: a flume open channel, a deposition board and a water intake box. To understand the particle segregation and movement mechanism of the limestone grain (2.5mm and 6mm) flow, a high-speed video camera (HSVC) is used to capture a video footage during short intervals of 0-40s. Besides using HSVC, video recordings of the tests were performed to analyze debris flow characteristics. This paper presents about the routing of limestone grains at two different slope angles which of 18° (mild) and 25° (steep). Results of the deposition patterns for each case are discussed.