Various trenchless technologies permit installation of buried thermoplastic pipes by pulling them into place through the ground. Pipe bursting uses a cone shaped expander to fracture an existing pipe, displace the resulting fragments out into the surrounding ground, and pull a new HDPE or other pipe into place through the resulting cavity. The expansion of the soil leads to vertical and lateral ground movements that can damage overlying pavements, and can also fracture pipe structures running parallel or transverse to the pipe being replaced.
John Cholewa designed and conducted a large scale pipe bursting experiment to replace a concrete sewer with a new HDPE pipe. Bending strains were measured in a PVC water pipe running transverse to the concrete sewer (see below). Post-test analysis provided the displacement profile of the PVC water pipe, and a new design method was proposed to permit consultants to estimate bending strains in PVC and other pressure pipes in the vicinity of pipe bursting operations.
John developed a unique fixture to simulate cyclic loading of HDPE pipe during directional drilling, length recovery after installation, and axial tension development after pipe attachment to appurtenances. Viscoelastic and viscoplastic analysis established that simple creep functions provide reasonable estimates of installation strains.
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