Abstract
This manuscript concerns the decrease of the structural strength and possible collapse of force (pressure) mains due to bedload erosion (abrasion), caused by low concentrations of hard solid particles transported with the sanitary sewage. Such a phenomenon may probably occur in combined sanitary systems (CSS), but it has also been observed in force mains delivering domestic sewage, due to occasional penetration of hard solid particles into the sanitary sewerage system. Force mains are usually subject to stresses originating from the internal pressure combined with those of the external load. For the design of such pipelines, Schlick's formula is usually applied. The present study applies Schlick's formula to represent the pipe failure curve. Then by properly introducing safety factors into Schlicks' formula the study defines service curves of the pipe. Each service curve is associated with a particular value of the pipe construction safety factor. In the next step by applying the concept of service curves the study hypothesizes the extension of Schlick's formula for possible calculation of the decrease of the pipe safety factor due to the presence of the invert groove. Calculations are made by using the ANSYS code, and the numerical results are applied to evaluate a particular case history of an asbestoscement (AC) force main collapse.
Highlights
This study has originated from a case history of asbestoscement (AC) pressure main collapse that took place in Tel-Aviv area, Israel
The information represented in this article indicates the resistance of the pipe wall material to abrasion may be an important factor for the life service of collection systems
Many studies refer to pipe abrasion due to the presence of high concentrations of hard solid particles transported with the water flowing through the conduit
Summary
This study has originated from a case history of asbestoscement (AC) pressure main (force main) collapse that took place in Tel-Aviv area, Israel. At the invert of the collapsed pipe a 40 mm wide and 20 mm deep groove has been found This groove has been the result of many years of bedload erosion caused by low concentrations of hard solid particles (sand and gravels) transported with the domestic wastewater delivered through that main. Manufacturing AC products like AC pipes has been banned in most developed countries (e.g., [1, 2]) including Israel. Such pipes are still at work for conveying water and wastewater in many places while providing good service. The force main in Tel-Aviv area collapsed on January 28, 2003, after about 30 years of completing its
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
