Effect of Geofoam Inclusion on Deformation Behavior of Buried Pipelines in Cohesive Soils

Abstract

The response of buried pipelines in cohesive soils with and without geofoam inclusion was studied extensively in this paper. Evaluation was made with the help of small-scale model tests. A series of small-scale models was performed in a fabricated box test setup, which defines the buried pipeline in cohesive soil. Black cotton soil emerged from basaltic formation in Maharashtra region of India was chosen to represent cohesive fill over and around buried pipes maintaining the constant embedment depth. Fabricated test setup was equipped with the front transparent glass panel to facilitate the capture of particle movements in the small-scale model during the increments of the loading. A 2-inch diameter HDPE pipe was used so as to represent prototype buried pipes. Geofoam was used as a compressible inclusion varying its density and cross sectional width. Plane strain conditions were adopted for all the tests. An image analysis technique was used to evaluate the performance of the geofoam in enhancement of deformation behavior of the buried pipe. Strip loading was applied with a constant load rate of 0.1 N/Sec using a Universal Testing Machine (UTM). This facilitates the correct evaluation of dissipation of the energy due to geofoam through soil arching and compression of the geofoam. Inclusion of geofoam around buried pipe prevents the adverse effects of unforeseen excessive forces on the pipeline resulting in minimal serviceability of the pipelines, reduced cost of maintenance, and reduced losses in the system and finally the effective economical operations in adverse geotechnical conditions. A maximum reduction of 32.14% was observed in the vertical deformations of buried pipe when a 150 mm wide low density geofoam was included beneath the shallow foundation at embedment depth equal to width of the footing.