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.

中文翻译：

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硫酸作用下桩土界面的分形表征及力学行为

本研究旨在研究混凝土受到硫酸腐蚀时桩土界面的不同性能。通过一系列大型直剪试验，研究了硫酸腐蚀对土与混凝土桩界面的影响。采用在硫酸溶液中浸泡不同时间（0、31、93和154天）的混凝土试件模拟硫酸环境下的混凝土桩表面粗糙度，比人工粗糙表面更逼真。沙子被用来模拟土壤。采用3D激光扫描技术对硫酸腐蚀混凝土试件的几何模型进行采集，并采用分形维数对硫酸腐蚀混凝土的表面特性进行评价。测量了砂与腐蚀混凝土界面的剪应力-位移曲线。获得了剪切强度参数和 Clough-Duncan 双曲线模型参数。建立了摩擦角与分形维数的关系。试验结果表明，随着腐蚀持续时间的增加，混凝土表面变得越来越粗糙，混凝土表面的分形维数、砂蚀混凝土界面摩擦角和峰值应力处的剪切位移变大。分形维数与界面摩擦角之间存在非线性关系。研究结果可为硫酸腐蚀混凝土材料与土壤界面行为的诊断、评价和分析提供参考。