Under the counterforce on the rectangular open caisson working well during pipe jacking

the backwall displacement curve was assumed to be parabolic and the relation between the displacement and earth pressure was used to calculate the earth counterforce. Then considering the friction forces on the well sides and well bottom

the permissible jacking force was calculated through the horizontal forces balance of the whole working well. Through an example comparing the new method with Rankine theory

it was shown that the new one can calculate the earth pressure at the un-passive state and considers the effect of the local force on the earth pressure distribution on the backwall.