Investigation of deformation properties of high-density polyethylene pipes under thermal effects

Today, the use of the HDPE (high-density polyethylene) flexible pipes is increasing day by day in drinking water, wastewater, sewerage networks, rainwater drainage lines, water transport structures and natural energy sources, etc. The main reasons why HDPE pipe is preferred over types such as concrete and steel are light, economical and long service life. In this master's thesis, flexible HDPE pipes embedded in the trench exposed them to variable relative density and different thermal conditions and deformation behavior were investigated. In the study, displacements and elastic strain values in the crown and springline regions were measured with LVDTs (linear variable differential transformer) and strain gauges. As a result, pipes with vertical loading were tested under 50%, 60%, 70% relative density conditions and -7°C, 26°C, 50°C thermal conditions. In the experiments carried out in the silica sandy trench, the deformations increased deformations and strains decreased due to the increase in relative density. Besides, the maximum displacemets and bending moment values were obtained in the case of 50°C which is the maximum thermal condition. The increase in temperature increased the deformation values due to the decrease in the modulus of elasticity.