Behavior of group piles under combined loadings after improvement of liquefiable soil with nanomaterials

Abstract

Abstract Earthquake-induced liquefaction is prone in a region with loosely saturated sand and higher seismic activity. In recent years, improvement techniques have been used as a pre-construction or retrofitting method for the current construction. Several methods are intended as remedial techniques, which include either densifying the deposit soil, inserting a unique material, or controlling dissipated pore water pressure generated during the seismic motion. The permeation grouting technique is primarily used in remedial liquefaction schemes that aim to improve the soil deposit mainly by cementing the soil particles and filling the void spaces, thereby preventing soil disturbance caused by settlements or distress to an existing foundation or structure. Permeation grouting involves the injection of a low viscosity chemical or particulate grout into the soil pores with little to no change in the soil structure and has been shown to be effective at reducing liquefaction risk beneath existing structures in soils where it is applicable. The mitigation of liquefaction risk by incorporating nanomaterials using the permeation grouting technique, to study the performance of a pile group embedded in the liquefiable treated layer with 1/50 nano-clay and 1/30 nano-SiO2 after 48 h of curing time during the Kobe earthquake, has been adopted. The soil profile treated using nanomaterials showed that the soil stiffness and strength were preserved during shaking because it did not liquefy; simultaneously, the maximum pile bending moments and lateral pile displacements in the treated soil layer were reduced by 30%. Finally, after treatment, the nanomaterials have a significant effect on the reduction of the maximum accelerations in two depths of soil.