Deep foundation pit structure above subway tunnel and construction method thereof

The invention relates to a deep foundation pit structure above a subway tunnel and a construction method thereof, and relates to the technical filed of deep foundation pits. The deep foundation pit structure comprises a soil layer and a subway tunnel arranged in the soil layer, a pile foundation is arranged in the soil layer, an underpinning beam is poured at the upper end of the pile foundation,a raft is arranged on the underpinning beam, and a shockproof and water proof layer is arranged on the lower plane of the raft. Retaining walls are arranged on the deep foundation pit structure, the inner side walls of the retaining walls abut against the raft, and supporting beams are arranged between the inner side walls. A plurality of separation plates which are distributed in the length direction of the supporting beams are arranged on the raft, each separation plate is located between the two retaining walls which are symmetrical to each other, each separation plate is vertically arranged and perpendicular to th