At-rest soil pressure is developed during the construction of bridge abutment. Active soil pressure are developed when the abutment are pushed forward by backfilled soils at the back of abutment wall. A state of equilibrium shall be reached when the at-rest pressure is reduced to active earth pressure. Hence, at-rest pressure is considered when assessing the stability of abutment while active pressure is adopted when assessing the adequacy of structural elements of abutment.
Passive pressure is only considered in integral abutment which experiences passive pressure when the deck expands under thermal effects.
Passive pressures are developed when the abutment wall pushes the soils at the front of abutment. Given that larger movements is required to mobilize passive pressure than active pressure and the abutment is designed not to slide under active pressure, it is normally assumed that passive pressure does not develop at the front of abutment. Moreover, there is a possibility that soils may be removed temporarily owing to utility diversion; it is normally assumed that stability contribution by soils in front of abutment is ignored.
This question is taken from book named – A Self Learning Manual – Mastering Different Fields of Civil Engineering Works (VC-Q-A-Method) by Vincent T. H. CHU.
If you have a query, you can ask a question here.
what is the term used when you build a bridge abutment out of soil and then add additional soil for settlement then remove the additional soil later on to build your concrete abutment