Influence Mechanism of Confining Pressure on Morphology of Concrete Crack Surfaces

Characterizing the morphological characteristics of concrete crack surfaces is fundamental for accurately analyzing the evolution mechanism of leakage in concrete linings. In this research, concrete crack surfaces are obtained using triaxial compression tests and three-dimensional (3D) laser scanning. The mechanism by which confining pressure influences crack morphology is further revealed, and the impact of crack morphology on tunnel lining leakage is illustrated from the perspective of fractal dimensions. The results indicate that the concrete crack surface flattens as the confining pressure increases. The distribution of asperity on concrete crack surfaces exhibits strong randomness. A negative exponential function can effectively depict the relationship between the fractal dimension of a concrete crack surface and the confining pressure. As the fractal dimension decreases with increasing confining pressure, concrete cracks developing under higher confining pressure exhibit a higher permeability coefficient, and tunnel linings become more susceptible to water leakage.