Remediation of piled foundations against lateral spreading by passive site stabilization technique

Physical modeling tests were conducted on pile foundations to measure the seismic performance of a new ground improvement technology, called passive site stabilization, for use on sites susceptible to liquefaction and liquefaction-induced lateral spreading. The method involves the slow injection of a low-viscosity stabilizer in conjunction with the natural groundwater flow. The effectiveness of the treatment using dilute colloidal silica as the stabilizer was tested by two centrifuge models that simulated soil–pile interaction of a 2×2 end-bearing pile group embedded in a multilayer soil deposit of 10-m thickness. The models utilized a laminar box and involved gently inclined soil profiles with and without the applied soil improvement. Response of the pile groups and the lateral spreading behaviors of the treated and untreated soil under a simulated base shaking were investigated and compared. The results showed that treatment with dilute colloidal silica stabilizer minimized permanent lateral deformations and reduced the liquefaction potential of the soil. Significant reductions occurred in the measured pile bending moments and axial forces because the layer treated with dilute colloidal silica did not liquefy. Thus, the technique can be an alternative to traditional methods of ground improvement.