Construction method and structure of immersed tube tunnel and shield tunnel

The invention relates to a construction method and structure of an immersed tunnel and a shield tunnel. The construction method comprises the following steps that an immersed tunnel line and a shield tunnel line are planned; the immersed tunnel is constructed on the immersed tunnel line; constructing a cofferdam at the junction of the immersed tunnel line and the shield tunnel line; an open-cut tunnel is excavated in the cofferdam, so that the open-cut tunnel is communicated with the immersed tube tunnel; a shield tunnel is constructed on the shield tunnel line; the joints of the open cut tunnel, the immersed tube tunnel and the shield tunnel are constructed; and after the backfilled cofferdam is covered with soil, the cofferdam is dismantled, and then construction is completed. The method has the beneficial effects that the immersed tube tunnel and the shield tunnel are communicated through the open-cut tunnel, and the problems that the immersed tube tunnel and the shield tunnel are directly communicated, so