Influence of Hole Geometry and Position in Leaking Pipes under Combined Pressure and Bending Regimes

Abstract

Strategies to reduce leakage based on integrated systems of monitoring and management of the pressure levels and related anomalies are acknowledged as the most reliable and cost-effective techniques to improve the efficiency of water networks. Because of their relevant impact at the large scale and the crucial roles currently played by programs envisaging ideas of smart cities capable to control/solve problems of homeland security and prevention and early monitoring of disasters and natural hazards, assessment and optimization of water networks have gained interest in recent years, overcoming the scientific fences of civil and hydraulic engineering and now being at the center of a wider vivid debate on how to maximize theoretical and experimental methods to increase security, reliability, and the so-called resilience of urban centers. Within this general scenario, this paper approaches the problem of the monitoring of leakage phenomena by focusing on the possibility of tracing the effects of the presence of not-necessarily circular holes on pipes subjected to combined water pressure and bending regimes, conceiving a parametric model which includes size, shape, orientation, and positioning of the hole, as well as different boundary conditions in the analyses to establish how they influence the final leakage. Sensitivity finite-element–based analyses are conducted to derive curves which could in principle serve, in combination with other consolidated strategies, to better identify position and amount of leakage phenomena. The outcomes are compared with the literature and in-house full-scale experimental findings, demonstrating good agreement between theoretical outcomes and laboratory results and gaining insight into advantages and limitations of the proposed strategy. It is felt that the developed approach, integrated with consolidated monitoring systems, might be useful to scientists and civil engineers in the management of existing hydraulic networks to estimate leakage volumes and predict more-realistic scenarios and related solutions for designing and planning practical interventions. This paper principally focuses on the hole geometry and position aspects, without addressing the hydraulic topic of discharge coefficient, in order to better understand the behavior of a leaking pipe.