Test and Study of Stress in Partly Restrained Section of Directly Burried Heat-supply Pipeline

摘要

Directly buried installation without expansion joint is a better layout to municipal heat-supply system of heat and power cogeneration. We carefully tested stress in partly restrained section (PRS), the diameter of which are DN600～700. The paper briefly introduces test project and methods; brings forward calculation formula of stress distribution, length of PRS, magnitude of expansion and contraction and average friction force factor. The results of the experimentation leads to establishment of the following proportional relationships: (1) L∝ΔT~(0.5), (2) L∝1/h, (3) ΔL ∝ΔT~(1.5), (4) ΔL∝1/h, (5) μ ∝ ΔT~(0.5) , (6) μ∝S, (7) μ∝Δ1/Dc; where L is length of PRS, ΔT is the difference in temperature, h is the distance between pipe and ground surface, ΔL is the magnitude of expansion and contraction, μ is the average friction force factor, S is pipe-sectional area, DC is insulating pipe's outside diameter.