Fractal characterization and mechanical behavior of pile-soil interface subjected to sulfuric acid

Abstract

This study aimed to investigate the different performance of pile-soil interfaces when the concrete was subjected to sulfuric acid corrosion. A series of large-scale direct shear tests were carried out to study the influence of sulfuric acid corrosion on the interface between soil and concrete pile. Concrete specimens immersed in sulfuric acid solution for different durations (0, 31, 93 and 154 days) were used to simulate the concrete pile surface roughness under sulfuric acid environment, which would be more realistic than the artificially roughened surfaces. Sand was used to simulate the soil. Geometric models of concrete specimens attacked by sulfuric acid were captured using a 3D laser scanning technology, and fractal dimension was adopted to evaluate the surface characterization of concrete subjected to sulfuric acid. The shear stress-displacement curves of the interface between sand and corroded concrete were measured. The shear strength parameters and the Clough-Duncan hyperbolic model parameters were obtained. The relationship between friction angle and fractal dimension was established. The results of the tests showed that with the increase of the corrosion duration, the concrete surface became rougher, the fractal dimensions of concrete surface, the sand-corroded concrete interface friction angle, and the shear displacement at peak stress became larger. A nonlinear relationship was found between the fractal dimension and interface friction angle. The results could provide a reference to diagnose, evaluate, and analyze the interface behavior between sulfuric acid corroded concrete materials and soil.