Buried Pipeline Response to Braced Excavation Movements

Abstract

This paper presents a detailed study to ascertain the response of a buried minor sewer pipeline consisting of three new manholes of 3.5- to 4-m deep and 89.7 m of 225-mm-diameter vitreous clay pipes to braced excavation ground movements. The pipeline and the manholes were supported on 6-m long, generally, of 65- to 75-mm-diameter Bakau (timber) piles embedded in 8- to 15-m-thick soft marine clay and peaty clay with an overconsolidation ratio of 1.2. The 34-m pipeline connecting two of the manholes ran parallel to a row of sheetpiles 9 m away. The sheetpiles formed one side of a strutted basement excavation about 9- to 10.5-m-deep. The excavation is part of an adjacent construction project. A recent oversite fill of 1.1 m has been placed to raise the site platform to avoid possible flooding throughout the area encompassing the pipeline and the adjacent construction project. Useful lessons which have been learnt from the study will be presented also.