Construction method for dismounting and replacing support of large connected complex deep foundation pit without partition wall

The invention relates to a large connected complex deep foundation pit support replacement construction method without a partition wall, which comprises the following steps of: firstly, presetting latticed columns and support connecting beams on one side of a support replacement position which is provided with a constructed main body structure bottom plate, a constructed main body structure column/wall and a constructed main body structure floor slab under the condition that the partition wall is not arranged; and then the foundation pit support can be detached and replaced by arranging a buttress wall and a buttress stand column, and the supporting axial force is underpinned to the buttress wall and the buttress stand column in an automatic servo system axial force compensation mode. Compared with the prior art, the support dismounting and replacing construction method for the large connected complex deep foundation pit without the partition wall has the advantages that support dismounting and replacing can