The deformation and force of pile-braced (-anchored) deep foundation pit is commonly determined by method of beam on elastic foundation (MBEF) during its construction process of excavation and support setting case. The existing MBEF uses the following steps for analysis: Firstly, the entire pile is divided into several segments at the braces, and then the continuous conditions of displacement and force balance conditions at the junction of the segments are used to derive the corresponding equations of the undetermined parameters, and then the deformation and force of the supporting system (foundation pit) are analyzed by using the determined parameters. Due to the different number of supports and segments corresponding to different cases, the method must rederive their respective parameter equations according to different cases, which result in complicated calculation process, difficult to form general calculation method and program. In view of the above problems, a recursive formula is established for the undetermined parameters between two adjacent segments by summarizing the support and pile segment into three basic connection forms (namely, the support is connected to the top of the pile, between the two adjacent pile segments and the bottom of the pit) , then deriving the general parametric equations applicable to strutted or anchored retaining structures, arbitrary number of supports and excavation or support setting case. The study results in this research verify the rationality and feasibility of the proposed method.

Pile-anchor (-strut) retaining structure is widely used in deep foundation pit, and the elastic foundation beam method is a common method to simulate and analyze the deformation and stress changes in the construction process of this kind of support of foundation pit. However, when applying this method for analysis, it is necessary to first divide a soldier pile into several segments at the braces for each construction stage, and then re-derive the corresponding undetermined parameter equations by using the continuous conditions of displacement and force balance conditions at the junction of the segments, resulting in difficulty to form a unified calculation formula and complication in the analysis method. In order to solve the above problems, by using δ-function to represent the concentrated force of brace on the soldier pile and re-solving the deflection equation of the soldier pile, a unified calculation formula is derived which applies to pit with strutted or anchored retaining structures, arbitrary number braces and case of excavation or brace setting. The new method not only avoids the subdivision of the soldier pile, but also forms a simple and unified calculation method. The numerical results of the method proposed in this article have only slight differences from the segmented method, indicating that the method is feasible.