Abstract: Selecting any one bracing plane on a pile as the research object, according to set up a bracing (or anchor or bolt) and excavation to the bottom of foundation pit, the force balance equation and the displacement coordination equation is established. Then through the collaborative working among the ring beam to them , the research object is extended to the entire bracing plane, to consider the excavation process, internal bracing to be set and soil-pile-ring beam interaction bracing plane displacement and force equations is derived. And then using FORTRAN language to solve the program, the horizontal displacement and internal force will be calculated to the ring beam and any section of the pile body to foundation pit excavation to bottom. Through a case study, it is shown that the calculated ring beam(pile top) displacements are consistent with monitoring results; and internal forces for some piles are consistent with calculated results by the references [1]. Finally, the proposed method is proved to be reasonable and feasible.

Key words: foundation pit, row of piles supporting, excavation process, internal force and deformation