EXPERIMENTAL STUDY ON HYDRAULIC PROPERTIES OF MANHOLES IN A SURCHARGED SEWER PIPE SYSTEM

Abstract

Manholes connecting sewer pipes are important elements in an urban drainage system. The manholes exert impacts not only on the local flows in their vicinities but also on the sewer flows in the whole pipeline system. For an appropriate assessment of the capacity and efficiency of a drainage system, and to improve the accuracy of numerical models for urban flood simulation, it is crucial to understand the hydraulic properties of manholes. In this study, a series of laboratory experiments have been conducted with a scaled physical sewer system model to clarify the local energy losses and local flow structure in a junction manhole. In particular, the influences of the lateral flow discharge ratio, the lateral pipe alignment angle and the outlet pipe submergence condition on the local energy losses have been analyzed. In addition, the local three-dimensional velocity structure in the manhole has been characterized.