Using EPS geofoam blocks to protect buried pipes against strike-slip fault movement

This study evaluates the benefits of the adoption of geofoam blocks to improve the seismic performance of buried steel pipes for simulating the complex material-structure interaction under strike-slip fault rupture conditions. Comparison of the response of improved models with conventional ones considering the parameters as fault crossing angle, fault slip amount and pipeline wall thickness is evaluated. A set of limit states was defined based on the violation of the tensile strain limit: onset of local buckling, rate of cross-sectional distortion and crushing of the EPS Geofoam blocks are adopted as performance criteria. Obtained results indicate that in general, the use of both low- and high-density geofoam blocks significantly improved the seismic performance of pipelines. The critical fault displacement value (dcr) leading to failure increases by more than 130% for high-density EPS. Moreover, use of geofoam blocks led to a more distributed damage pattern along the pipe, thus reducing localized strain accumulation and eventually pipeline failure. Additionally, increasing the fault crossing angle (β) from 10° to 30° and reducing the pipeline diameter-to-wall-thickness ratio (D/t) from 144 to 58 to enhance the beneficial effect of geofoam blocks in critical fault displacement value seemed to be achievable.