Currently

it is still controversial whether isolation piles can effectively reduce the deformation of underground structures outside foundation pits.In order to study the effect of isolation piles on lateral soil displacement induced by excavation

a three-stage method is presented to study the soil movement outside isolation piles after excavation by combining the two-stage method and the stratum compensation method

and the rationality of the proposed method is verified.The calculated results show that

under different excavation depths and deformation modes of the foundation pit

lateral soil displacement in a certain depth range under the ground surface can be reduced by the isolation piles

however the horizontal displacement of the deep soil is increased;with the increase of the stiffness of the isolation piles

the isolation effect on the lateral displacement of the top soil becomes more significant

but there are more deep lateral soil displacement;the drag effect to the deep soil due to the isolation piles can be reduced with a reasonable buried depth.When consider setting isolation piles to protect the underground structures outside the foundation pit

its feasibility should be comprehensively analyzed according to the simulate results

the practical engineering condition and the local experience.