Combined type inner formwork for variable cross-section immersed tube pouring and construction method of combined type inner formwork

The invention relates to the technical field of immersed tube tunnel construction, in particular to a combined type inner formwork for variable cross-section immersed tube pouring and a construction method of the combined type inner formwork. The inner formwork system comprises a middle section formwork, and an outer side formwork and an inner side formwork are arranged at the two ends of the middle section formwork respectively. One side of the variable cross-section compensation template is connected with the middle section template, and the other side of the variable cross-section compensation template can support the outer side template; the die further comprises a side die compensation template which is arranged at the bent position of the outer side template. By adopting the combination mode of the inner formwork system, the variable cross-section compensation formwork and the side formwork compensation formwork, the inner formwork system can adapt to pouring of the variable cross-section immersed tube,