Relationship between seepage water volume and total suspended solids of landslide dam failure caused by seepage: an experimental investigation

Prakash Dhungana,Fawu Wang

doi:10.1186/s40677-020-0144-6

Abstract

BackgroundLandslide dams inevitably demonstrate the potential for catastrophic failure with high-risk damage to life and property at the downstream site. Hence, knowledge of the internal stability of dam materials is a key to predicting the seepage failure of landslide dams. In this study, experiments were conducted to examine the relationship between seepage volume and total suspended solids (TSS) of seepage water based on hydro mechanical constrains. Understanding the relationship between the seepage volume and TSS with hydro-mechanical constraints supports the prediction of the seepage failure of landslide dams at the field level.ResultExperiments were conducted with a mixed sample of silica sands. Seepage water was collected from a flume tank with the facility to measure the hydraulic gradient, vertical displacement, and seepage water volume. Grain size affected the life span of the dam. The seepage volume increased with the increase in the percentage of silica sand S4, whereas TSS increased with the increase in the percentage of silica sand S8. With the increase in the dam height, the dam life decreases for low coeficient of uniformity of the grain size distribution. With the increase in the reservoir size, TSS decreased, and the total seepage volume increased.ConclusionDam failure depends on the particle size, dam geometry, inflow rates, reservoir size, hydraulic gradient, and seepage water volume, and TSS of seepage water. The results indicated that with the increase in fine particles, the life span decreases, and TSS increases. With the increase in the flow rate, the dam life span decreases, and the TSS and seepage volume rate increase.The dam height leads to an increase seepage volume with low TSS, where the life span of the dam also depends on the particle size distribution With the increase in the reservoir size, the seepage water volume decreases with low TSS.

Highlights

Formation and failure of landslide dams in mountainous areas constitute a significant natural hazard
Experiments were conducted to understand the effect of the dam height, reservoir size, and inflow rate into the reservoir on hydraulic gradient, vertical displacement, total suspended solids (TSS), seepage water volume, and longevity of the dam for three soil samples prepared by the mix of silica sands S4, S5, S6, and S8
The density of the dam controlled the time for the initial peak hydraulic gradient, whereas density exhibited a lower effect for the total life span in contrast to the initial peak hydraulic gradient (Fig. 3)

Summary

Introduction

Formation and failure of landslide dams in mountainous areas constitute a significant natural hazard. The inflow rate into the reservoir and reservoir volume, dam size, and dam material are important factors that affect the failure of a landslide dam (Schuster and Costa, 1988). Some authors already reported the statistics of landslide dams and their failure in various regions worldwide. They have summarized the important characteristics of landslide dams including their classification, cause and type of failure, life span, and some other important parameters (Costa and Schuster, 1991; Korup, 2004; Stefanelli et al, 2015; Xu et al, 2009; Casagli and Ermini, 1999; Chai et al, 1995; Clague and Evans, 1994). Understanding the relationship between the seepage volume and TSS with hydro-mechanical constraints supports the prediction of the seepage failure of landslide dams at the field level

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Conclusion