RELIABILITY ESTIMATION OF BURIED PIPELINES USING FIRST ORDER RELIABILITY METHOD

摘要

Corrugated polyethylene (PE) pipes are used widely and have characteristic to resist environmental stresses from chemical and biological agents. Since the corrugated PE pipes provide substantial benefits over concrete, metal and other traditional pipes. Furthermore they are easy to install, tough in the field, durable in service and environmentally benign. In this paper, the limit state function (LSF) is formulated in accordance with conventional design method. The FORM (first order reliability method) is utilized to extract useful technical information in carrying out the effective design procedure for corrugated PE pipe. Using the three design criteria and failure probability, the methodology for reliability estimation of corrugated PE pipe is investigated. The effects of varying design parameters on failure probability are systematically studied. For three design criteria, it is found that the bending stress design criterion shows the smallest failure probability and the deflection design criterion shows the largest failure probability for varying design parameters. It is recognized that the failure probability increases with growing of the COV of random variables. It is also noted that the design parameters such as burial depth, modulus of soil reaction, outside diameter, pipe stiffness, soil density and distance to neutral surface must be selected properly to target a required safety level.