Three Dimensional Numerical Analysis of Static Pipe Bursting
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During pipe bursting, a cone shaped expander is pulled through an existing pipe, breaking it, enlarging the cavity, and pulling a replacement pipe into place. The expansion of the soil cavity and axial movements of the burst head cause ground disturbance, and infrastructure such as other buried pipelines and overlying pavements may be damaged. Pipe bursting involves a complex three dimensional response of the ground surrounding the old pipe. A three dimensional numerical study has therefore been undertaken to explicitly simulate propagation of the burst head, and study the response of soil and adjacent pipelines in detail. A description of the ABAQUS modeling is presented, focusing on the analysis of pipe bursting experiments conducted using the buried infrastructure test facilities at Queen’s. The ground surface deformations, pulling forces and strains on an adjacent polyvinyl chloride pipe were computed and compared with experimental observations. On average, the computed results differ by 20% compared to experimental values. In addition, the stress and strain responses of soil were analyzed to explain the failure mechanism of soil during progression of the burst head. A parametric study was conducted by changing the burial depths, expansion ratios, trench widths, and material properties to provide a general guideline for ground movements during pipe bursting. The analysis was further extended by changing the positions (under, over, beside) and orientations (perpendicular or parallel) of adjacent pipelines with respect to the pipe being replaced. Use of the parametric study was illustrated and evaluated using a large scale pipe bursting test. The computed results are about 20% conservative compared to the experimental values of peak vertical deformations and peak longitudinal strains of adjacent pipe.