According to new explanation about the m-method in Code for Pile Foundation of Harbour Engineering Supplement and the test pile data of two large diameter rock-socketed steel pipe piles in a wharf

the power function relationship between the constant m value and pile head deflection is concluded; and even the behavior of pile reaction under the influence of m value is obtained too. These can reach a conclusion that the m values suggested in the code can not be used in the case of large deflection. Therefore

by collecting lots of test pile data

it is necessary to establish the corresponding relationship between the m value and large deflection under different soil conditions based on that relationship described in this paper. These results can help to provide reference for lateral loaded pile design.