TRANSVERSE HORIZONTAL LOAD ON BURIED PIPES DUE TO LIQUEFACTION-INDUCED PERMANENT GROUND DISPLACEMENT

This paper investigated the transverse horizontal load on buried pipes due to liquefaction-induced permanent ground displacement in the horizontal direction. The focus of study was on the maximum load. For this purpose, liquefaction-induced permanent ground displacement in areas behind quay walls and in inland sloping ground areas was reproduced in a model ground and the load exerted on pipes buried in this ground area was measured. The investigation employed dynamic centrifuge model tests. All pipes were buried in non-liquefaction layers situated above liquefaction layers. All of the obtained load due to liquefaction-induced permanent ground displacement in the horizontal direction were much smaller than the load obtained by moving pipes forcibly in a static ground. The ratio of the maximum load due to liquefaction-induced permanent ground displacement to that obtained by moving pipes forcibly was about 0.3-0.4. There is a possibility that a maximum load corresponding to the residual strength of the ground was exerted on the pipes. The ground displacement patterns suggest that large shear strain was generated on the rear side area of the pipe. The cracks on the front side area of the pipe may have decreased the confining pressure of the ground and resulted in the decrease of the load. The tensile strain generated in the ground may have decreased the confining pressure and resulted in a decrease in the load as well.