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 other

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.

Thanks Dr Amkad for brief answer