Abstract:
Urban flooding in low-lying areas of Colombo has intensified due to increased
monsoonal rainfall and inadequate gravity drainage capacity, necessitating reliable
stormwater control infrastructure. The Oliyamulla Stormwater Pumping Station
was developed as a flood mitigation measure within the Peliyagoda-Kelaniya
drainage basin and incorporates six vertical sliding gates to regulate pumped and
gravity-driven discharges to the Kelani River. Accordingly, an electrically hoisted
sluice gates or vertical gates were designed that overcame significant engineering
challenges to ensure safe and reliable gate operation. This paper presents the
design and implementation of a mechanically robust and cost-effective hoisting
system for vertical sliding gates with significantly different sizes, weights, and
operating heads. The design methodology involved analytical evaluation of hydrostatic
thrust, buoyancy, friction at guides and seals, and dynamic lifting forces.
Maximum operating loads of approximately 76 kN per spindle for pump outlet
gates and 178 kN per spindle for gravity-flow gates were derived using standard
hydraulic load formulations with appropriate safety factors. The spindles are
90 mm in diameter and manufactured from stainless steel Grade 304. Power
requirements were calculated from the lifting forces and target spindle speed, resulting
in the selection of 7.5 kW and 11 kW geared motor systems operating
at lifting speeds of approximately 0.34 m/min. Structural integrity of the screw
spindles was verified against Euler buckling, thread wear, and combined stress
criteria, while the hoisting platform was validated using SAP2000 finite element
analysis. The finalized systems achieved reliable dual-mode operation with overload
protection and adequate safety margins. The novelty of this work lies in the
unified design approach that standardizes spindle size and transmission components
across heterogeneous gate configurations while complying with American
Water Works Association (AWWA) and Indian Standards (IS), thereby providing
a practical solution for urban flood control infrastructure.
