Experimental research on mechanism of scour by submerged jets in consolidated clay

Abstract

This study presents a rapid consolidation device for clay, coupled with a systematic investigation of submerged jet scouring behavior in consolidated clay under varying parametric conditions (soil strength: 25–40 kPa; jet velocity: 7.5–12.5 m/s; nozzle diameter: 5–7 mm; target distance: 0–3 cm). The developed graded vacuum preloading method demonstrates remarkable efficiency in producing hardened sediment specimens (compaction time <192 hr) that exhibit comparable physical properties to naturally consolidated reservoir deposits that have formed over many years. Experimental findings reveal a linear proportionality between shear strength and dry density. Notably, the cohesive nature of consolidated clay fundamentally alters scouring mechanisms through interparticle cementation effects, distinguishing it from non-cohesive soil behavior. Temporal evolution analysis shows the scouring depth follows a second-order exponential growth pattern, progressing through four characteristic phases: (Ⅰ) short start stage (0–3 s), (Ⅱ) rapid development stage (3–35 s), (Ⅲ) slow expansion stage (35–60 s), and (Ⅳ) stable stage (>60 s). Parametric sensitivity studies establish positive correlations between scouring efficiency and jet velocity as well as nozzle diameter, while demonstrating inverse relationships with both target distance and soil strength.