A 190 m long flume for investigation of debris flow impacts on multiple flexible barriers

Debris flows, consisting of mixtures of poorly sorted soil, rock and water, surge downstream along channelised paths, causing significant casualties and infrastructure damage. Mitigation typically involves installing barriers along potential flow paths to arrest the material. Laboratory flume experiments are established methods for investigating the physical mechanisms of debris flow mobility and flow–barrier interactions, although they often fail to capture the scale-dependent nature of debris flows reliably. To address this limitation, a new 190 m long, 6 m wide flume facility, the largest of its kind, has been constructed in Kunming, China. In this study, a test was conducted using a total volume of 180 m³ of debris material to explore debris flow interactions with multiple flexible barriers, monitored by various sensors and instruments installed in the flume and the barriers. Results highlight the effectiveness of multiple flexible barriers in mitigating debris flows, showing progressive reduction of impact forces, landing distance and retention volume while moving downstream. Existing design criteria for estimating impact forces and barrier spacing in a multiple barrier system are validated. This research underscores the flume’s capability to provide valuable, reproducible data, offering new insights into flow–barrier interactions, calibrating numerical models and contributing to the development of rational design guidelines.