Abstract: The pile anchors are used widely as supporting structure. But in excavation, the stability of foundation with the prestressed anchors and displacement hasn't been solved yet. Additional stress caused by prestressed anchors influences on the stability and displacement of foundation, the expression between prestress and the stability of the pile anchor supporting structure, and the equation of horizontal displacement and structure stability are formulated. In a typical foundation pit, comparisons of the calculation results by general design software show that: 1) The prestress is considered as additional stress to calculate the overall stability safety factor of foundation pit, and the safety factor increases with increasing prestess; there exists a non-linear relationship between the safety factor and prestess; 2) Similarly, the displacement of the pile anchor supporting structure can be calculated by the forementioned way; and horizontal displacement of retaining structure decreases as prestress increases, which presents a non-linear relationship; 3) The expression of relationship between the stability safety coefficient of supporting structure and the horizontal displacement of retaining structure is given, which is more suitable for theory and engineering practice; 4) Compared with the calculation method for stability and displacement of the foundation pit considering prestress, the existing design of the pile anchor supporting structure is conservative and still needs to be validated and corrected according to a large number of engineering practices. 5) We first study the relationship of stability of pile anchor supporting structure and horizontal displacement considering additional stress, which can provide theoretical foundation for dynamic stability evaluation of foundation pit in the process of excavation.

Key words: retaining structure, prestress, additional stress, horizontal displacement, stability