Bed Load Erosion Patterns and Their Effect on the Structural Strength of Rigid Pipes Made of Homogeneous Materials

Hillel Rubin,Holger Schuttrumpf,Eran Rubin,Dmitry Tokarev

doi:10.2174/1874149520130417001

Abstract

This manuscript concerns the decrease of the structural strength of rigid pipes made of homogeneous materials due to bed load erosion, caused by different concentrations of hard solid particles transported by the sanitary sewage, or surface runoff. Such a phenomenon has been observed in combined sanitary systems (CSS), as well as in force mains delivering domestic sewage due to the penetration of hard solid particles into the sanitary sewerage system. Field observations have indicated that the low concentrations of solid particles transported with the sewage lead to the formation of a groove at the pipe invert. Experiments carried out in this study have shown that the width of the groove mainly depends on the concentration of the solid particles. Numerical simulations have indicated that bed load erosion resulting from very low concentrations of solid small particles may be more detrimental to the structural strength of the pipe than higher concentration of such particles.

Highlights

This study has originated from a case history of asbestoscement (AC) force main collapse occurring in Tel-Aviv area, Israel [1]
At the invert of the collapsed pipe a 20 mm deep and 40 mm wide groove has been found. This groove has been the result of around 30 years of bed load erosion caused by low concentrations of hard solid particles transported with the domestic wastewater delivered through that force main
The reported field observations concerning the development of grooves at the invert of force mains [1] probably indicate that in such pipes this phenomenon is very much expected, because the settling system existing at the suction side of the wastewater pumping station leads to settlement of most quantities of grit present with the wastewater

Summary

Introduction

This study has originated from a case history of asbestoscement (AC) force main collapse occurring in Tel-Aviv area, Israel [1]. In comparison to the broad range of themes connected with sediment transport in water sheds, open channels, canals and pipes, the subject of pipeline abrasion by sediments has been attracted very moderate attention. This topic is very much relevant to transport of various types of slurry through pipes [e.g., 2, 3] because the transported high concentration of solid particles of the slurry causes continuous decrease of the pipe wall thickness due to its abrasion. Pipe selection for sewerage and drainage systems considers the pipe resistance to abrasion, because this parameter is assumed to affect costs of maintenance and there is a need for rehabilitation or replacement of such systems

Objectives

Conclusion