Improved analytical solution of vertical pressure on top of induced trench rigid culverts

Induced Trench Installation (ITI) is a viable option to reduce the load on rigid culverts buried under high embankments. However, reliable design methods are limited, which restricts further applications of this technology. Based on Marston's formula, a modified analytical solution is proposed, in which the vertical stress across the width of the soil column immediately above the compressible layer is assumed to be distributed in a parabolic shape, and the effects of the geometry and stiffness of the soft layer on load reduction are considered explicitly. Comprehensive comparisons are made between field monitored results and the calculations from different design methods. Parametric studies are subsequently conducted to investigate the influence of different distribution patterns of vertical stress and the properties of the soft layer. It is found that compared to Marston's theory, the proposed method yields a closer estimation to the field measured data. Finally, a simplified design chart is introduced, which can facilitate use of the proposed method.