Structures are usually designed on assumed values of the dry density and the peak angle of shearing resistance of the backfill. However, whilst the use of backfills with significantly higher material properties may produce a stronger structure and lower settlements, the superior backfill could be seriously detrimental to an integral bridge construction, as integral bridges are reliant on the expansion and contraction of the bridge deck being accommodated by rotation of the bridge abutment, instead of by expansion joints or bearings. During demolition of a redundant bridge abutment, data were collected to investigate the states of compaction of the in situ granular fill. Results of tests on the fill material demonstrated that higher values of the internal angle of friction were produced by higher states of compaction. The implications of the findings on the design of integral bridges are discussed and recommendations made on potential ways of minimising these effects. (A)
Abstract