Stability of block mattress under non-uniform flow downstream of sluice gate

Abstract

Downstream of hydraulic structures, the flow is normally of turbulence. This will cause considerable erosions on the gravel bed. To prevent this, block mattress is preferable in many cases. Its effective stabilization and feasibility on construction make it commonly used against scouring problems, protecting underwater pipelines and cables. The currently widely used design formula with dedicated parameters for block mattresses was derived by Pilarczyk. However, it is observed to be partly functioning under non-uniform flow condition, since the turbulence parameter is rather empirical. Therefore the main purpose of this thesis is to optimize the current design formula (Pilarczyk’s) for non-uniform flow condition. In this flow regime, turbulence is of importance for bed material entrainment. Thus this research focused on how to introduce turbulence effect into formula explicitly. To predict the failure of block mattress better, a detailed study on failure mechanism and impact of flow condition over the block mattress edge is necessary.