Earth pressure measurements on buried HDPE pipe

An understanding of the stress distributions that act on buried pipes plays a key role in the development and use of design methods for these structures. The radial stresses that develop on buried flexible pipes have been investigated by a number of researchers through experimental, analytical and numerical methods. However, direct measurements of soil contact stresses acting on small-diameter pipes have not been possible, since commercial earth pressure cells are large, and the stiffness of the cell relative to the soil material is known to influence the measured stresses. A new technique is described for measuring the radial contact stresses acting on buried pipes, and experimental studies are reported that demonstrate the effectiveness of this new technique for measuring contact pressures for both loose and compacted sand backfills. Comparison of the measurements with computations from elastic soil-pipe interaction theory reveals significant discrepancies in the magnitude and distribution of radial pressure around the circumference of the pipe for both loose and compacted backfill conditions. The new measurement technology provides direct support for pressure distributions inferred in earlier studies from measurements of circumferential strains around the pipe circumference.