Automatic as-built management of retaining grid frame structures using point cloud data

Abstract

Extreme weather and earthquakes are boosting demand for slope protection on steep terrain. Retaining grid frame structures—lattice-type concrete grids—must be surveyed precisely, yet rope-work-based manual measurements are labour-intensive and hazardous. This paper presents an as-built management method that (1) separates grid frame and slope surfaces in point cloud data, (2) creates cross-sections, and (3) outputs width, height and frame center distance for every frame. Tests on a 60 m curved site in Fukushima showed mean dimensional error of 0.02 m, satisfying the Japanese guideline tolerances (±0.10 m for frame center distance and ± 0.03 m for both width and height), and an F1-score of 0.92 for slope surface detection with reliable rope removal. The workflow lowers field labour, enhances safety.