Analytical Approach for Evaluating Pressure on Buried Conduits with Reinforced Granular Soil Cover

Buried rigid conduits in trench installations are commonly protected by exploiting positive soil arching, which reduces the vertical stress transmitted to the conduit crown. The combined use of a soft compressible inclusion and horizontally placed geosynthetic reinforcement offers a more efficient integrated system by simultaneously enhancing the arching effect and introducing membrane-based load spreading. This study presents a closed-form analytical framework for evaluating the behavior of buried rigid conduits in geosynthetic-reinforced backfill trenches, considering unreinforced, singly reinforced, and doubly reinforced configurations. The influence of the elastic modulus and thickness of the soft material, the interface friction factor, the surface surcharge, the backfill depth, the geosynthetic tensile stiffness, and the number of geosynthetic layers on the axial strain, tension force, conduit crown pressure, and overall system efficiency is examined through a comprehensive parametric study. Key findings include the following: For a singly reinforced system with a soft backfill height and a granular embankment fill depth 1–2.5 times the width of the soft backfill, the overall efficiency increases from 62% to 75.7% as the soft-material elastic modulus decreases from 2,100 to 350 kPa. Moreover, the doubly reinforced system achieves an efficiency of 84.4%, compared to 77.9% and 60.5% for the singly reinforced and unreinforced systems, respectively. The analytical model is verified against published results, demonstrating excellent agreement in predicted geosynthetic strain and tension. A step-by-step design example is also included to illustrate the use of the proposed procedure.