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The effects of induced trench configuration and stiffness of compressible inclusion on the HDPE pipe behavior were investigated through full-scale laboratory tests. Two pipe-compressible inclusion configurations (“compressible inclusion over the pipe crown” and “the pipe covered with compressible inclusion”) were tested and EPS Geofoam with 10 and 15 kg/m³ nominal density was used as compressible inclusion. To simulate geostatic stresses imposed by high embankment fill, the surcharge stress up to 200 kPa was applied on the surface of the burial medium. Comprehensive instrumentation was implemented to measure the pipe deflections, soil stresses on the pipe, and soil settlements in the pipe zone. Considering the pipe behavior and cost-efficiency together, the configuration in which one EPS Geofoam panel with 10 kg/m³ nominal density is placed over the pipe crown arises as the optimal solution for the induced trench HDPE pipe. This solution provided a reduction in the vertical stress at the pipe crown up to of 76% and in the horizontal stress at the pipe springline up to of 65%. The vertical and horizontal pipe deflections are reduced by 87% and 60%, respectively, under 200-kPa surcharge stress. i.e., overburden pressure imposed by a 10-m-high embankment fill.

Expanded polystyrene (EPS) block (geofoam block) is a mature geotechnology for constructing highway embankments. In addition to preventing bearing capacity and settlement related stability problems for the embankments constructed on soft soil sites, geofoam blocks are also used to construct embankments atop existing infrastructure. Selecting geofoam technology for these applications not only prevents the possible structural problems due to the lightweight nature of geofoam blocks but also eliminates costly remediation alternatives. The details of three well-documented and monitored different geofoam embankments constructed atop different existing infrastructures (buried pipeline, buried culvert and pile cap of drilled shafts for a deep excavation) are presented. The backgrounds of these projects, design considerations, construction and instrumentation details are discussed. The monitoring results were presented, and long-term performance predictions were evaluated. Numerical modelling effort was utilized to model the both short- and long-term behavior of geofoam embankments. Time-dependent behavior of the embankments under service loads were compared with numerical simulations. Constitutive modelling and related mechanical properties of geofoam blocks, which mimicked the long-term field behavior, as a function of geofoam density were proposed for future numerical modeling efforts.