Abstract: The new prestressed subgrade (PS) technology can be used to treat subgrade diseases or strengthen existing subgrades. It is of great significance to study the prestress loss law to ensure the long-term safety of PS project. Based on the elastic theory, an analytical method is developed to calculate the additional stresses on the horizontal path behind the center point of the lateral pressure plate-embankment slope interface. The analyzed results show that the horizontal additional stress on this feature path decreases with increasing the distance away from the center point in a good exponential relationship. According to the exponential diffusion law of the horizontal additional stress and the creep behavior of the subgrade soil, a formula is derived to calculate the creep deformation of the subgrade soil, and a prestress loss model and calculation method are then established for PS based on the deformation coordination of the embankment soil creep and steel bar contraction. Comparative analyses are consequently performed using the proposed method and FLAC3D numerical simulations. The results show that the theoretical prediction curves of the pre-tension loss of the steel bar is in good agreements with the numerical simulations with a deviation less than 5%, which indicates the effectiveness of the proposed prestress loss model of the PS. The pre-tension force of the steel bar stabilizes within 60 days after anchored, and the stable pre-tension force reaches 85%–90% of its initial value, which demonstrates that the new PS technology could provide considerable stable additional confining pressure for the subgrade soil, so as to strengthen subgrade by improving the stress state of the subgrade soil.

Key words: prestressed subgrade, additional stress, creep effect, prestress loss, coupling effect model, numerical simulation