Determination of critical shear stress of non‐cohesive soils using submerged jet test and turbulent kinetic energy

Abstract

AbstractLaboratory tests using Jet Erosion Testing (JET) apparatus, impinging normally on a horizontal boundary, were conducted to determine the critical shear stress (τc) of non‐cohesive soil samples. A three‐dimensional (3D) SonTek/YSI 16 MHz Micro‐Acoustic Doppler Velocimeter (MicroADV) was used to measure turbulent kinetic energy (TKE) at a radial limit of entrainment in the wall jet zone and the measurements were used to calculate τc of the samples. The results showed that TKE increases exponentially with increasing particle size. The τc from this study were comparable (R2 = 0.8) to the theoretical τc from Shields diagram after bed roughness scale ratio (D/ks), due to the non‐uniform bed conditions, was accounted for. This study demonstrated that JET and TKE can be used to determine τc of non‐cohesive soils. The use of JET and TKE was found to be faster and easier when compared to the conventional approach of using flumes. A relationship of TKE at the onset of incipient motion (TKEc) and samples’ D50 developed in this study can be used to predict τc of non‐cohesive soils under similar non‐uniform conditions. Copyright © 2015 John Wiley & Sons, Ltd.