Experimental study of scour dynamics around elongated piers with pile caps

Pier geometry of bridges encompasses various characteristics, including type, dimensions, and shape. Pier types range from single-column to multiple-column configurations, with options such as rectangular shapes, and various pile arrangements (friction or tip bearing, with or without footings or pile caps). Footings or pile cap may be embedded in the bed, rest on the surface, or be exposed within the flow. Key dimensions include diameter for circular piers, spacing for multiple columns, and the width and length for elongated piers. Shapes vary from round, square, or sharp-nosed profiles to circular cylinders, groups of cylinders, or rectangular forms. Complex pier configurations may expose the pier, footing or pile cap, and piles to the flow. While various scour conditions have been explored in literature, the influence of footings at the base of elongated skewed piers has received relatively less attention, despite being prevalent in real-world applications. This study presents results from physical models focusing on elongated piers with rounded noses and tails, accompanied by footings of varying planimetric dimensions. Experiments were conducted under clear water conditions near critical thresholds, analyzing the temporal evolution of scour depth until near-equilibrium. Results from a single elongated pier are compared with those from a circular pier, providing insights into maximum scour depth and its spatio-temporal evolution, thus informing proper design practices.