Effects of Reinforcement on Liquefaction Resistance of Solani Sand

A study on liquefaction resistance of Solani sand reinforced with geogrid sheet, geosynthetic fiber, and natural coir fiber is reported. Tests were carried out on shake table (vibration table) with sand samples prepared at a relative density of 25%, with and without reinforcements. Synthetic geogrid sheets were used in three different combinations of three, four, and five layers. In case of fibers, the percentage of fibers by weight of dry sand were taken as 0.25, 0.50, and 0.75% and mixed randomly with the sand sample. The liquefaction parameters, such as the maximum pore water pressure ($U_{\max }$), maximum pore water pressure built-up time, stay time for $U_{\max }$, and pore water pressure dissipation time were measured corresponding to various levels of accelerations varying from 0.1–0.4 g. The frequency of the dynamic load was kept constant at 5 Hz. The liquefaction resistance of sand was evaluated in terms of maximum pore water pressure ratio ($r_{u\max }$). Test results indicated that on inclusion of fibers and geogrid sheets into the sand samples, the $r_{u\max }$ decreased. On increasing the fiber content and number of geogrid sheets, $r_{u\max }$ decreased further, and this decrease is significant at a small amplitude of excitation. The average increase in liquefaction resistance of sand reinforced with synthetic and coir fibers was found to be 88 and 91%, respectively, for 0.75% fiber content, whereas for five layers of geogrid sheets, this increase was about 31% at 0.1 g acceleration.