Construction method for shield to penetrate through shallow-covered urban landscape lake downwards

The invention discloses a construction method for a shield to penetrate through a shallow-covered urban landscape lake downwards. The construction method comprises the steps of film bag cofferdam constructing, wherein a film bag cofferdam is constructed at the area to be excavated, and film bags are laid according to locating piles driven in advance; grouting reinforcing, wherein grouting reinforcement is carried out in the constructed film bag cofferdam; macadam dumping and filling, wherein macadam is dumped in the area of the film bag cofferdam and compacted so that a lakebed cannot be easily damaged in future, and the dumping and filling order is changed to the lake center from the bank side; and shield driving, wherein the shield penetrates through the urban landscape lake downwards, the film bag cofferdam is removed in order, the shield advances from a vertical shaft and penetrates through a reinforced area, and the advancing parameters are adjusted according to real-time survey data for completing tunne