Experimental Investigations of Backfill Conditions on the Performance of High-Density Polyethelene Pipes

Abstract

In this study, a series of laboratory tests on 100‐mm‐diameter high‐density polyethylene (HDPE) 100 PE flexible pipe buried in poorly graded Sile quartz sand with different relative densities are described. The laboratory tests were performed in a 40‐mm‐thick plexiglass fronted test tank that replicated a classical trench section in field conditions. The HDPE flexible pipe was positioned against the glass with its longitudinal axis perpendicular to the glass. This allowed direct observation of the backfill–pipe interactions. Three high‐definition photogrammetric cameras were used to capture the photogrammetric images through the glass allowing the discrete measurement and image processing of the deformation patterns of the pipe conduit during the pipe installation and incremental surcharge loading. Vertical loads were applied in increments of 10–150 kPa using air pressure membranes. Electric resistant strain gauges measured the bending moments of the pipe walls under vertical surcharge loadings. For each loading step, the vertical deformation of the pipe crown was also measured using linear position transducers. According to the test results, it is understood that the installation technique and backfill relative density have an important effect on circumferential strains, performance, and deformation characteristics of HDPE pipes. It was also observed that close‐range image processing is a very simple and appropriate method for measuring three‐dimensional pipe deformations under various conditions.

Numerical and Experimental Investigation of the Effect of Traffic Load on the Mechanical Characteristics of HDPE Double-Wall Corrugated Pipe

“…Von-Mises stress can be expressed by the stress component, as shown in Equation (8). Previous studies have focused on the circumferential stress and changes in the diameter of the flexible pipe to indicate the deformation of the pipe [9,16,23,51]. Compared with the real stress, the von-Mises stress comprehensively considers the deformation of materials in multiple directions, and the assessment of the ductile failure of pipes is more accurate; thus, it is reasonable to take the Von-Mises stress as a parameter that indicates the deformation of the pipe [52][53][54].…”

“…Talesnick et al (2011) designed a new technique to measure the radial contact pressure applied to a buried pipe and the deflection of the pipe under static vertical loading, and the measurement results indicated that the radial contact pressure and deflection of the pipe were sensitive to the compaction backfill [15]. Terzi et al (2012), through a series laboratory tests on HDPE pipes buried in poorly graded sand with different compaction, found that the stress and deformation of these pipes were higher when the surrounding backfill was loose, and the maximum stress appeared at the invert, whereas the crown stress and invert stress were higher when the backfill was compact [16]. In addition, the method of installation and the type of backfill material were also key factors that affected the deformation of the pipe.…”

Numerical Investigation of the Short-Term Mechanical Response of Buried Profiled Thermoplastic Pipes with Different Diameters to External Loads

“…(2012) buried HDPE pipes in poorly graded sand with different compaction degrees to measure the strain response of pipe to external loads. e results indicated that when the backfill around the pipe is loose, the maximum strain occurs at the invert of the pipes, and when the backfill is fully compacted, the maximum strain occurs on the crown of the pipes [20]. Brachman et al (2008) conducted laboratory experiments to compare the effects of compaction methods, backfill materials, and gradation on the deflection, strain, and local bending of special-shaped thermoplastic pipes.…”

Steel-Reinforced Polyethylene Pipe: Extrusion Welding, Investigation, and Mechanical Testing

“…High-density polyethylene (HDPE) pipe, well known as a type of thermoplastic pipe, is used instead of concrete and steel pipes for many applications, such as gas and fluid transfers, water/sewage drainages, and electrical and communication conduits (Refs. [1][2][3]. The HDPE pipe shows many excellent properties, such as light weight, chemical resistance, and tolerance for decomposition (Ref.…”

“…Although HDPE pipe has been appropriate for underground applications, it also has high ductility and low stiffness, which causes an unstable shape when it receives highly compressive forces (Refs. 3,4). Recently, the strength of HDPE pipe has been improved by methods such as increasing the wall thickness, spiral shape designs, and reinforcements such as fiberglass and ceramic, etc.…”