Experimental investigation on the formation process of landslide dams and a criterion of river blockage

Abstract

River blocking caused by landslide dams is a common geological disaster in mountainous regions worldwide, threatening the safety of human lives and infrastructure. However, studies on the formation process of landslide dams and the criteria of river blockage are still at an early stage. This paper built a laboratoryscale experimental apparatus for simulating the formation and evolution process of landslide dams, and then carried out a total of 29 experiments. It analyzed the common evolution stages of river blocking, including landslides, dam formation, and dam breaching in detail. Then, we investigated the influences of the landslide volume, the landslide discharge, and the water flow rate on a criterion and the time length of river blockage. The experimental results suggest that the formation condition of a landslide dam is related to the ratio of the landslide discharge to the water flow rate. Based on this understanding, we proposed a dimensionless River Blockage Criterion (RBC) to judge the formation of landslide dams. The criterion indicates that when RBC > 1.5, a landslide dam may form; otherwise, a landslide dam may not form. Additionally, the time length of river blockage was found to be related to the landslide volume and the water flow rate. Subsequently, we proposed a model for predicting the time length of river blockage and verified it by the 29 experimental results. The Baige River-blocking event, which occurred on the Jinsha River, China, in 2018, was used as a case study to further verify the RBC and the proposed model. The results show that the proposed RBC agreed well with reality, and the percentage difference between the calculated and the actual time length of river blockage was 11%. The findings of this study could contribute to the early warning and emergency response of river-blocking disasters.

Influence of Internal Structure on Breaking Process of Short-Lived Landslide Dams

“…Through analysis, an empirical formula to evaluate the breaking form of the landslide dam on the spot was presented, the relationship between the growth rate of the dam breach area and the growth rate of the saturation degree, and the final dam breach area and the final saturation degree were proposed, as well as the mechanism of the moment when the peak flow occurs was found. Combined with early identification of highrisk areas of landslide dam and life prediction of landslide dam (Chen et al, 2019a;Chen et al, 2019b;Nian et al, 2020), the pre-burst disaster assessment of the short-lived landslide dams could be more effective.…”

“…However, it is difficult to make model tests similar in experimental phenomena to meet these conditions. To make the experimental phenomena closer to reality, the similarity of coupled water and soil motion is also necessary (Nian et al, 2020). Due to the limitations, researchers can only make the experimental models meet similarity criteria as much as possible.…”

Numerical Simulation on the Longitudinal Breach Process of Landslide Dams Using an Improved Coupled DEM-CFD Method

“…During this process, due to the fragmented dam materials with large pores inside, the seepage flow would first appear at the foot of the downstream slope. Once the water level overtops the dam crest, dam breaching commences through overtopping erosion (Nian et al, 2020). Figure 6 shows the typical temporal sequences of the landslide dam breach process (scenario C2).…”

On Dam Failure Induced Seismic Signals Using Laboratory Tests and on Breach Morphology due to Overtopping by Modeling

“…Many researchers use small indoor flumes to perform tests for landslide dam breaches [25][26][27][28]. Most of the tests explored the erosion of the dam body, including the effects of different flume slopes, dam geometry, and material properties.…”