Soil Parameters for Assessing Axial and Transverse Behavior of Restrained Pipelines—Part 2: Transverse Behavior

Abstract

Understanding soil-structure interaction behavior of the pipe-soil interface is essential in the characterization and assessment of thrust restraint resistance mechanisms in buried pipelines. Two primary forms of resistance mechanisms, axial and transverse, contribute to the resistance of unbalanced thrust forces that arise at a bend, valve, tee or other similar sources of thrust in a buried pressure pipeline. The individual contribution from each mechanism depends on the material properties and constitutive relations of the pipe segments, pipe joints, soil, and the soil-pipe interface; internal and external loadings on the pipeline; and installation conditions. In the water/wastewater industry, pipeline designers frequently rely on guidance from AWWA standards and design manuals. These guidance documents are developed by distinct material-specific standard committees, and the contents are based on differing simplifying assumptions, theories and design philosophies and are often uncoordinated. In most cases, the rationale behind the recommended soil parameters is either undocumented or based on unidentified assumptions. This practice leads to inconsistent guidance on selection of soil parameters for use in the soil-structure interaction analysis of different pipe materials, and makes improvement of design practices to be extremely difficult.