Safety supporting device for deep foundation pit excavation

The utility model relates to the technical field of deep foundation pit excavation, in particular to a safety supporting device for deep foundation pit excavation, which comprises a bored pile and a cast-in-place pile, the cast-in-place pile is arranged on the inner side of the bored pile, supporting and protecting structures are arranged on the inner side and the outer side of the cast-in-place pile, and each supporting and protecting structure comprises a stand column pile. After a drilling machine drills a hole, concrete is injected to reliably manufacture a bored pile, the first steel support and the bored pile are reliably connected through the top beam, personnel injury caused by top side earthwork collapse is avoided, the concrete is poured into the reinforcement cage to form a cast-in-place pile, the bracket and the stand column pile, and the second supporting plate and the third supporting plate are installed at the top end of the bracket. Therefore, the first steel support, the second steel support