Experimental study of uplift of buried pipe liquefiable soil at different depths

In recent earthquakes, many buried structures, including tunnels and lifelines, have been seriously damaged. It is noteworthy that the phenomenon of soil liquefaction has a significant role in the occurrence of these damages. The enormous damage because of soil liquefaction, has motivated the study of uplifting of lifelines. Therefore, in this research, it has been attempted to study uplift of buried pipe in liquefiable soil by physical modeling. The soil used in this study was Gum tape sand and the shaking table was used to simulate the seismic load. Also, due to the importance of the deformation mechanism in this process, particle image velocimetry technique has been used. The buried pipe (at three depths of 1.5, 2.5 and 5 times the diameter of the pipe) has been subjected to seismic load and then deformation mechanism of it has been discussed. The results show that by decreasing the buried depth of the pipe, due to the relatively high pore water pressure at the lower soil depth, the overpressure created after the dynamic loading tends to dissipate and flow to low pressure points (surface area) and because of upward flow in the surface area, the uplift will continue to some extent. Also, the displacement vectors around the pipe are circular rings that try to uplift the pipe.