Composite pile-anchor supporting method and structure for deepening excavation

The invention relates to a foundation pit supporting method for deepening excavation. When secondary deepening excavation is conducted on an excavated foundation pit, on the basis of an original foundation pit supporting system, a new supporting system, which comprises supporting piles II and new top beams II, is arranged at the bottom of the excavated foundation pit, and the original foundation pit supporting system is tightly connected with the new supporting system by virtue of new waist beams II and new connecting beams so as to form a composite supporting system. When the deepening excavation is required on a constructed foundation pit supporting project, the original supporting system cannot provide enough resistance, and the original foundation pit supporting system and the new supporting system are connected by virtue of the new waist beams II and the new connecting beams, so as to form the integrated composite supporting system. In the composite supporting system, the original supporting structure is utilized sufficiently; on the basis of ensuring the safety and the stability of the foundation pit, the purposes of facilitating the construction and shortening the construction period are achieved; and the scheme ensures the continuous construction during the subsequent excavation stage of the foundation pit project.