With the increasing pressure, a crack in a medium will be gradually closed, which is affected by stress interactions. The closing process of parallel cracks under vertical stress is simulated here. The coplanar and stacked cracked models are constructed to analyze the influence of two types of stress interaction on the closing process. The spatial distribution of cracks, demonstrated by numerical experiments, has a significant impact on stress interactions and thus the process of crack closure. The mechanisms underlying the delay of crack closure caused by stress interactions are different for the two models. Furthermore, according to the stress dependence of crack microscopic parameters (crack porosity, aperture, and length of major axis), the process of crack closure can be divided into three stages: the linear deformation stage, the contact stage, and the closure stage. In the first stage, no contact is permitted inside the crack. The shielding effect directly leads to a closure lag, and thus a linear stress dependence of the microscopic crack parameter. In the second stage, the shielding effect determines the increasing rate for the stress dependence of microscopic crack parameters in regularly distributed cracked models. However, for the randomly distributed cracked model, local stress interactions result in the eccentric closure of cracks, and thus the crack closure lag. In the last stage, the crack is closed and stress interactions disappear both in the regularly and randomly distributed models.

The deterioration of concrete hydraulic structures caused by chemical factors, seepage, and environmental stress necessitates advanced protective coatings that enhance durability, flexibility, and environmental sustainability. Conventional protective systems often exhibit limited durability under combined hydraulic, thermal, and chemical stress. In this study, a novel polyfluorosilicone-based coating system is presented, which integrates a deep-penetrating nano-primer for substrate reinforcement, a crack-bridging polymer intermediate layer for impermeability, and a polyfluorosilicone topcoat providing UV and weather resistance. The multilayer architecture addresses the inherent trade-offs between adhesion, flexibility, and durability observed in conventional waterproofing systems. Informed by a mechanistic study of interfacial adhesion and failure modes, the coating exhibits outstanding high mechanical and performance characteristics, including a mean pull-off bond strength of 4.56 ± 0.14 MPa for the fully cured triple-layer coating system, with cohesive failure occurring within the concrete substrate, signifying a bond stronger than the material it protects. The system withstood 2.2 MPa water pressure and 200 freeze–thaw cycles with 87.2% modulus retention, demonstrating stable mechanical and environmental durability. The coating demonstrated excellent resilience, showing no evidence of degradation after 1000 h of UV aging, 200 freeze–thaw cycles, and exposure to alkaline solutions. This water-based formulation meets green-material standards, with low volatile organic compound (VOC) levels and minimal harmful chemicals. The results validate that a multi-scale, layered design strategy effectively decouples and addresses the distinct failure mechanisms in hydraulic environments, providing a robust and sustainable solution.