It is a great breakthrough in ocean heavy industry that the manufacturing of the first rail-mounted 2 × 11 000 ton gantry crane in the world, as well as direct unloading, split and assembling for super-heavy industry products. To meet requirements on the rail foundation with extreme heavy loading and strict deformation criteria, a new structure type of composited steel pipe pile and sheet pile with extreme wide integrated relieving slab is developed. No well developed calculation method can be referred at the moment due to its structural complexity. The bearing mechanism and calculation method remain the topics for further research.