Introduction  Large diameter cellular sheet pile cofferdam has been applied in practice recently due to the advantage of construction speed and less pollution to the environment. However, the design method of this cofferdam in soft clay is still in its infant.

  Method  Taking a large diameter cellular sheet pile cofferdam in an artificial island project in China as an example, this study focused on the potential problems in its design in soft clay. Three different methods were used to calculate the stability of the cofferdam. These methods included China′s code method, Japan′s code method and three-dimensional finite element method.

  Result  The results show that the earth pressures of foundation calculated by China′s code method are smaller than that of the other two methods. The overturning point is located at the un-overturning side of the cofferdam based on the results of Japan′s code method and the finite element method, whereas it is fixed at the front toe point of the cofferdam in China′s code. The safety factor of overturning failure by China′s code method is larger than that of the other two methods due to the different positions of the overturning points.

  Conclusion  This showed that more work of the design code method and theory should be conducted on large diameter cellular sheet pile cofferdam in soft clay foundation.