Traditional layer-wise summation method cannot take the three-dimensional deformation of foundations into account

which results in very large calculation error on foundation settlement. In order to reduce the range of correction factor of layer-wise summation method

a calculating method of flexible foundation settlement is derived based on e-p curves from confined compression test

which can consider three-dimensional deformation of the foundation. The new calculating method can consider lateral deformation of the foundation soil on the basis of layer-wise summation method when the compression amount of each layer calculated by the traditional calculating method is multiplied by a correction factor. Further

by adjusting the pressure distribution on the foundation base

an approximate calculating method of rigid strip foundation settlement is derived. The numerical example shows that the new calculating method considering three-dimensional deformation can solve the problem that it will get smaller settlement on the small size foundation when using traditional layer-wise summation method. From the calculation results

settlement of the small-size rigid foundation calculated by new calculating method is larger than that calculated by traditional method; while settlement of the large-size rigid foundation calculated by new calculating method is smaller than that calculated by traditional method

which may be one of the reasons that correction factor of layer-wise summation method is in a wide range. The application of this new method can reduce the calculation error of layer-wise summation method.