Analysis of erosion characteristics of mountainous area bridge piers based on three-dimensional refined measurements

In order to investigate the characteristics and development patterns of erosion damage in bridge piers in mountainous areas, a three-dimensional refined measurement method of concrete bridge pier surface erosion based on LiDAR and binocular cameras with infrared structural light is proposed. Consequently, a method for calculating the erosion volume of bridge piers based on the three-dimensional measurement data is established. Field tests conducted on two large bridges located in the Hengduan Mountains area yielded high-accuracy three-dimensional data of pier erosion. This study discusses the erosion characteristics and the variation pattern of erosion with pier height for both cylindrical and octagonal bridge piers. Field observations indicate that the erosion mainly occurs on the water-facing surfaces; the primary source of erosion for cylindrical piers comes from suspended sediments, and the erosion depth is related to the pier height following a power function relationship. The erosion on octagonal piers is severe, with some areas exposing longitudinal and hoop reinforcements, primarily caused by large-sized drift rocks in the river during flood periods. The results can provide references for the measurement of erosion in mountainous area bridge piers and for the design of erosion protection.