Miscellaneous fill foundation pit upside-down well wall reverse construction method excavation construction method

The invention provides a miscellaneous fill foundation pit upside-down well wall reverse construction method excavation construction method which comprises the steps that a plurality of foundation pits are excavated on the ground, a lock mouth ring beam is constructed on each foundation pit, after the lock mouth ring beams reach 75% of the design strength, excavation is conducted downwards to form a vertical shaft, when the foundation pits are excavated, the foundation pits are excavated at intervals, and a supporting structure is erected while excavation is conducted. After the foundation pit is excavated to the shaft bottom of the vertical shaft, the bottom of the shaft bottom is sealed, a bottom plate waterproof layer is constructed, an over-excavation area is backfilled, a formwork is installed, then a secondary lining structure is poured, and after all the vertical shaft structures reach the design strength, the formwork is removed, a top plate waterproof layer is constructed, a soil layer is backfilled,