the efficiency of a collar in reducing the scour depth around circular and rectangular piers is studied at different flow intensities (ratio of upstream shear stress to sediment critical shear stress). rectangular piers aligned with the flow as well as skewed at 5º, 10º, 20º were examined. previous studies had shown that with collar the equilibrium time of scouring increases considerably. to re...

Estimating maximum scour depth is normally required in order to determine the depth of  bridge piles. The present paper uses the SSIIM Software which considers flow and sediment equations in a three dimensional manner. The software models flow field around circular bridge pile by resolving Navier-Stokes three-dimensional equations and k-  method, and by temporary solution of flow field and cont...

Prediction of the scour around a group of pile in the field exposed to oscillatory waves is very important for many offshore structure and coastal engineering projects. Conventional predictive formulas for the geometric properties of scour hole, however, are not able to provide sufficiently accurate results. In this paper the ANNs approach is used to predict the scour depth around pile group us...

local scour around the abutment is of utmost importance in bridge failures. numerous methods such as riprap have been proposed to reduce the destructive effects of scouring; one of the ways to harness and reduce the local scour depth is installed protective collars around the abutment. in this paper effect of collar elevation (upper level, bed level and lower level), collar geometry and its siz...

An experimental study has been conducted on the effectiveness of two types of flow-altering countermeasures placed around a cylindrical pier under clear water condition, which include sacrificial piles and submerged vanes. Their arrangements follow the optimal configurations recommended in the published articles with some modification. The temporal evolution of maximum scour depth and its equil...

A series of experiments was conducted to investigate the erosion behaviors of the noncohesive sediments downstream of smooth and rough aprons. A total of 33 tests were carried out with five different roughness conditions (k =0, 1, 1.85, 3.35 and 5mm) in a flume 0.5m wide, 0.6m deep and 9m long. For each run, s measurements were taken of the scour-hole profiles at the asymptotic or equilibrium s...

This study addresses the design of riprap aprons as a scour countermeasure near abutments under clear-water conditions. It deals with the lateral extent of riprap aprons and the geometry of the scour hole prevailing at the apron edge. The study applies to riprap aprons acting as granular filters. The scour depth appears to be independent for a sufficiently long relative abutment length. Scour h...

stable pile depth in the Snowy River study (SKM 2005) is outlined. The inputs used in the run of the LLP99 model were: • single soil layer, • very high flexural stiffness of pile (1,000,000 kN/m). • pile width = 0.3 m (i.e. wooden pile), • shear strength in the absence of lateral stress (for unconsolidated sand 150 kN/m was used), • effective unit weight of soil (15 kN/m), • active lateral effe...