Assembling method of combined immersed tube immersion barge

The invention relates to an assembling method of a combined immersed tube sinking barge, and belongs to the technical field of immersed tube tunnel construction. The assembling method comprises the following steps that the two mounting cross beams are connected to form a combined body, and the two floating bodies and the combined body are transported to the position above a to-be-constructed area; the two floating bodies are controlled to sink, the two floating bodies are moved to the positions below the two ends of the combined body correspondingly, and the two floating bodies are made to be parallel; the two floating bodies are controlled to float upwards so that the combined body can be supported through the two floating bodies, and the combined body is located between the same longitudinal ends of the two floating bodies during supporting; in the combined body, the cross beam close to the longitudinal end part of the floating body is a first cross beam, and the other cross beam is a second cross beam; dis