FAILURE MECHANISMS OF BURIED PIPELINES UNDER FAULT MOVEMENT AND SOIL LIQUEFACTION (EARTHQUAKES)

Lifelines, such as oil and gas transmission lines and water and sewer pipelines have been damaged heavily in recent earthquakes. The damages of these lifelines have caused major, catastrophic disruption of essential service to human needs. Two seismic hazards are (a) fault movement and (b) soil liquefaction.; (A) Fault Movement. In this investigation, a non-linear analysis for buried pipeline subjected to tensile strike-slip fault is proposed with following conditions. (1) The conditions of using elastic foundation for the far end of the pipe and the ultimate passive soil pressure near the fault are used to derive the basic equations of a pipeline crossing an active fault. (2) An iterative method is used to solve the non-linear equations induced from the non-linearity of material and soil characteristics and large displacement.; This study also discusses the design criteria for buried pipelines subjected to various fault movement and other design parameters.; (B) Soil Liquefaction. This is an initial research to investigate the performance of a pipeline in a soil liquefaction environment during earthquakes. The pipeline is subjected to longitudinal wave propagation at the time of liquefaction of soil deposits.; A simplified pipe model on a time dependent elastic foundation is proposed to stimulate a liquefaction situation of a liquefiable zone during earthquakes and the finite difference technique coupled with a time-increment computer solution is employed to determine the dynamic responses of the proposed model numerically.