Pre-pressing anchor cable sinking beam method process for controlling excavation deformation of foundation pit above existing tunnel

The invention discloses a pre-pressing anchor cable sinking beam method technology for controlling excavation deformation of a foundation pit above an existing tunnel, and belongs to the technical field of foundation pit excavation deformation control. The pre-pressing anchor cable sinking beam method technology comprises the following steps that excavation partition division is conducted on the range of the foundation pit to be excavated, in each foundation pit excavation partition, a back pressure sinking beam is constructed along the earth surface, and an anchor cable opening is reserved; drilling towards the lower stratum along the anchor cable opening of the back pressure sinking beam, placing an anchor cable body, and performing grouting treatment on the lower part of the anchor cable body to form an anchor cable anchoring section; the exposed end of the anchor cable is locked at the top of the back pressure sinking beam through a rotatable lock and a sliding supporting plate; performing layered excavat