Effects of Soil Properties on Earthen Dam Breach Characteristics

Abstract

The dynamic behavior of earthen dam breaches, influenced by the mechanical and erodibility properties of soil, is necessary for both dam safety and flood risk predictions. This study investigates the sensitivity of six key soil properties: median grain size (d50), coefficient of uniformity (Cu), bulk density (ρb), critical Shields number (θc), angle of repose, and bed-load coefficient (α), on peak breach discharge (Qp), final breach width (Wf), time to peak discharge (Tp), and total failure time (Tf), using a one-at-a-time sensitivity analysis approach. The dam breach is simulated using FLOW-3D Hydro on non-cohesive, earthen-dam breach flow initiated in a pilot channel carved in the dam crest. The results show that all the parameters studied had the same proportionality with the breach characteristics, except for the bed-load coefficient, which showed an adverse proportionality. Among them, d50 and θc have the strongest influence, followed by ρb. The sensitivity also varied among the breach characteristics parameters, with Wf being more responsive than Tf. These findings underscore the critical role of the mechanical and erodibility properties of soils in dam-breach modeling and offer valuable insights into their impact on spatial and temporal breach development.