Theoretical analysis and physical modeling of stone columns-improved ground under shaking loading

The stone column technique is one of the liquefaction mitigation methods used in liquefiable deposite. Owing to the higher permeability of stone column materials than that of the surrounding soil, the stone columns may expedite the drainage process of the excess pore pressure under seismic loading so that to partly or completely eliminate the triggering of liquefaction. One stone column with the influenced surrounding soil is treated as a representative element, and based on the previous analytical solution to this problem, the analytical solutions for vertical and radical drainages are obtained by considering the excess pore water pressure on the boundary of single stone column-influenced area as the known condition. The centrifugal model tests on stone column-improved ground are carried out. The total drainage water in the centrifuge model improved by stone columns is calculated using the above analytical solution, and is further converted into the settlement based on the equivalent relationship between the seepage discharge and the volumetric change of the surrounding soil. The calculated settlement is found to be in good agreement with the measured one in experiment, which verifies the proposed solution. Furthermore, the evolution of horizontal and vertical drainages of stone column composite deposite in the model tests is analyzed by combining the derived analytical solutions for water drainage with the test results.