Abstract: Taking the new type prestressed subgrade as the research object, theoretical formulas for calculating the diffusion coefficient of additional stress perpendicular to the slope surface in an embankment induced by a prestressed reinforcement device (lateral pressure plate and prestressed bar) were derived based on the theory of elasticity. The presstress diffusion trends directly beneath the plate bottom as well as in the two external directions were analyzed. The results show that: 1) the applicable condition of the theoretical formulas requires that the net distance between the plate (with a side length of 0.9 m) and embankment shoulder should be not less than one time of the plate width; 2) the diffusion effects of the normal component force are much greater that those of the tangential component force; 3) due to the tangential component force, the total diffusion stress directly beneath the plate bottom presents a “raised abdomen” pattern and it gradually transits to a uniform “flat abdomen” pattern as the depth increases; 4) the maximum diffusion coefficient of the additional stress at different depths fluctuates on the plate centerline as the depth increases; 5) the diffusion effects in different zones show a descending order, i.e., directly beneath the plate bottom > the outside of the upper boundary > the outside of the left and right boundaries > the outside of the lower boundary, and the average effective diffusion depth in the two directions is about 1.6 m. A refined 3D FEM model using the ABAQUS software was established to verify the theoretical formulas. It was found that the finite element results (including at the embankment shoulder) agree well with the theoretical data, which demonstrates the validity and applicability of the theoretical formulas. Finally, the rational plate spacing was explored based on the distribution of the superimposed additional stress under the action of multiple lateral pressure plates to form a continuous, effective and relatively uniform preloading area at a certain depth. The prestressed reinforcement device can improve the stress state of the soil embankment and provide lateral constraints to the embankment slope, which is beneficial for the long-term stability of the subgrade.

Key words: new prestressed subgrade, lateral pressure plate, additional stress field, diffusion law, spacing arrangement