Electrical resistivity change of saturated sand during reliquefaction under hammering loading

The electrical resistivity method was verified as an optional technique to monitor the change of mesostructure of saturated soils. To investigate the change laws of resistivity and analyze the reliquefaction meso-mechanism during the consecutive liquefaction process, five successive impact liquefaction tests were performed in a one-dimensional cubical chamber. The resistivity variation and excess pore water pressure (EPWP) were measured. The results indicate that the excess pore water pressure experienced four stages: quick increase stage, slow dissipation stage, rapid dissipation stage, and stability stage. Meanwhile, a swift decrease of resistivity emerged before the start of the rapid dissipation stage of EPWP, and then an increasing trend of resistivity is demonstrated with the densification of soil. It is proved that the vertical pore connectivity of liquefied sand is better than its random deposit state, based on a comparative study of porosity calculated from the settlement and resistivity of sand after each test.