Integral supporting device for deep foundation pit and supporting method thereof

The invention provides an integral supporting device for a deep foundation pit and a supporting method thereof. The device comprises an enclosing purlin, a structural bottom plate, reinforced concretesupporting columns and opposite supports, wherein the U-shaped enclosing purlin is additionally arranged at the position, in a pit, of the reinforced concrete supporting columns on the outer side ofthe deep foundation pit; and the enclosing purlin and the reinforced concrete supporting columns of the foundation pit are connected in a bar planting mode; top steel bars of the reinforced concrete supporting columns are anchored into the structural bottom plate, so that the structural bottom plate and the reinforced concrete supporting columns are fixedly connected; and opposite support steel bars are anchored into the structural bottom plate. The local support and bottom plate connecting mode can reduce the influence of a temporary structure on a permanent structure in the construction process, and the exposure time