Analysis of the nanoparticles effect on the stability of buried porous concrete pipes containing fluid flow using the numerical method

Buried porous concrete pipes, which are used with fluid flow underground or in porous environments, are one of the vital innovations in subsurface structures. However, the stability and optimal performance of these pipes in the face of fluid flow are related to multiple issues including chocolate change, corrosion, and structural resistance reduction. In recent years, with the advancements in the field of nanotechnology, adding nanoparticles to the concrete environment in order to improve various properties has become one of the strategies to study and improve the stability of buried porous concrete pipes. Considering the widespread applications of perforated concrete pipes containing fluid flow in civil engineering, providing a suitable mathematical model for analyzing their stability and dynamic performance is essential. In this regard, a buried concrete pipe is formulated, taking into account the permeability in concrete materials and the surrounding soil, reinforced with silica nanoparticles. The structure is modeled using cylindrical shell elements and by employing the theory of elasticity. To calculate the force induced by the fluid flow inside the pipe, the Navier-Stokes equation is utilized. The influence of nanoparticles in the pipe is modeled using a mixing model, and the soil bed is simulated using vertical springs and shear layers. Finally, by applying Hamilton's principle, the governing equations of the structure are extracted. The Bezier finite element method is employed for structural analysis, and the effects of parameters such as the volume fraction of nanoparticles, concrete permeability, soil bed, fluid inside the pipe, and geometric parameters are investigated. The results of the analysis indicate that with an increase in the volume fraction of nanoparticles from zero to 3%, the maximum frequency and critical fluid velocity increase by 35% and 38%, respectively. Additionally, as the concrete permeability increases from zero to 6.0, the maximum frequency and critical fluid velocity decrease by 26% and 18%, respectively. These findings can contribute to the improvement and optimization of the design of concrete pipes containing fluid flow, enhancing our understanding of the dynamic behavior of these structures.