ABSTRACT
Sand lenses are frequently encountered deep inside saturated clay deposits located in areas prone to earthquakes. When a strong earthquake takes place in these areas, the sand lenses liquefy. After liquefaction, sand volcanoes appear on the surface of the clay deposits containing the lenses. To date, there is not a clear explanation of the mechanisms involved in the movement of the liquefied sand lenses from their original location in the clay deposits. According to current accepted theory, the liquefaction of the sand lenses is the result of shear stresses induced in the sand by seismic shear (S) waves. Another seismic wave that has been overlooked in liquefaction and post-liquefaction studies of sands is the compressive or P wave. This study presents a laboratory experiment that uses a shaking table that vibrates horizontally and a saturated clay mass containing a simulated liquefied sand lense. The results of this test indicate that the cause of movement of a liquefied sand lense seems to be the compressive stress induced in the clay by the P waves.
