Nonlinear analysis and design of surface anti-seepage polyurea coating considering multiple action effects
The polyurea anti-seepage coating system has been extensively used in hydraulic structures due to its superior long-term durability and mechanical properties,and fine robustness to construction surfaces in contrast with polyurethane coating.In view of the lack of structural design theory for polyurea coating system,the experi-ence-based design method commonly used may lead to unsafe,unreasonable and uneconomic results.In this study,the key theory concerning the nonlinear analysis of surface anti-seepage polyurea coating was discussed,and a nonlinear FEM models was built to investigate the mechanical behavior,peeling behavior,and failure mode of the polyurea coating under various conditions,such as substrate surface fracturing,surface hydraulic pressure,and joint deformation.The main conclusions are as follows:(i)Concerning the combined substrate surface fracture and hydraulic pressure condition,the peeled coating at the crack location exhibits a tensile-bending stress state.(ii)Coating material damage may occur at the stress concentration point.(iii)The maximum stress increases with the increase of the hydraulic pressure and cohesive strength,and the peeling length of the coating decreases with the increase of cohesive strength and increases with the increase of fracture width.(iv)Concerning the joint deformation condition,the peeling length increases with the coating thickness and joint deformation width,and the peeling length decreases with the cohesive strength.(v)The maximum stress increases with the coating thickness,cohesive strength and the hydraulic pressure.Finally,the frame of design and simple design program were proposed.
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