Numerical investigation on erosion characteristics of elevated pile cap in high concentration sediment flow environment

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The objective of this investigation is to study the erosion process and characteristics of elevated pile cap in high concentration sediment flow environment, taking into account the influence of multiple factors. Firstly, a three-dimensional model of elevated pile cap was established and used for numerical simulation of erosion. Subsequently, the validity of the elevated pile cap erosion numerical model was corroborated through a comparison with the results of existing physical model tests. Finally, the influence of hydrological conditions, structure geometric characteristics, and material properties on the erosion characteristics of the elevated pile cap were investigated. The numerical results demonstrate that the sand content, flow velocity and pile longitudinal clearance diameter ratio are positively correlated with the abrasion thickness and erosion rate of the elevated pile cap. The pile diameter, the pile transverse clearance diameter ratio, and the compressive strength have a negative correlation with the abrasive thickness and erosion rate of the elevated pile cap. When the particle diameter increases from 0.2 to 2.0 mm, the erosion rate of the pile foundation first decreases and then increases. If the bearing platform is not fully submerged, the erosion rate of the elevated pile cap decreases with the increase of water depth. As the water gradually submerges the bearing platform, the erosion rate of the pile foundation increases with the increase of water depth. And with the change of impact angle, the shielding effect of the front pile on the back pile will also change, which has a great influence on the downstream piles erosion. This study not only enriches existing erosion theories but also guides erosion protection of the elevated pile cap.