Assessment of Scouring Effect of Msingi Masonry Arch Bridge in Mkalama, Singida, Tanzania
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Date
2025-08-26
Journal Title
Journal ISSN
Volume Title
Publisher
ABUAD Journal of Engineering Research and Development (AJERD)
Abstract
This study presents an integrated geotechnical and hydraulic assessment of the Msingi Masonry Arch Bridge in Mkalama
District, Singida, Tanzania, to evaluate scour vulnerability, subsurface strength, and structural load capacity. Field investigations
included Dynamic Probing Light (DPL) testing, core sampling, and particle size analysis at six test pits (DS1–DS6), alongside
laboratory tests adhering to BS 1377:1990 standards. Results revealed significant spatial variability in soil gradation and compaction,
with deeper layers demonstrating high bearing capacities (up to 1555.8 kN/m²), while surface strata exhibited loose conditions and
higher susceptibility to erosion—particularly in zones with elevated fines content. Hydraulic modelling, using site-specific parameters
such as hydraulic radius (1.88 m), channel slope (0.0082), and Manning’s coefficient (0.017), predicted a scour depth of 2.6 m,
compared to the observed 2.0 m. Structural analysis using the MEXE method yielded an allowable axle load of 28.05 tonnes, translating
to a foundation pressure of 98.6 kN/m², which is within safe soil capacity limits. Despite current structural stability, the narrow scour
margin and near-threshold loading conditions indicate elevated long-term vulnerability. The study recommends immediate installation
of scour countermeasures, selective foundation deepening in weak zones, and routine monitoring to enhance the resilience and longevity
of the bridge.
Description
This Journal Article was Published by ABUAD Journal of Engineering Research and Development (AJERD)