Enhancing the seismic performance of piles in liquefiable soils by slag powder

Case studies show that earthquake-induced soil liquefaction can cause large lateral deformation of piles, leading to bridge damage. In this study, an iron and steel manufacturing by-product, slag powder, was utilized for the first time to mitigate soil liquefaction, thereby reducing the lateral deformation of piles during earthquakes. First, the liquefaction resistance of soil improved by slag powder was analyzed by cyclic triaxial tests. The results indicate that as the slag powder content increased, the soil liquefaction resistance increased. When the cyclic stress ratio is 0.2, the number of liquefaction cycles of the reinforced soil increases by 30 compared with that of the unreinforced soil. Second, a numerical modeling method of slag powder reinforced sand was proposed and validated by the cyclic triaxial test results. Third, the seismic response of piles in liquefiable soils enhanced by slag powder was evaluated using finite element analyses, and slag powder was determined to be effective in decreasing the lateral deformation of piles in liquefiable soils, the maximum displacement of the pile was reduced by 45 %. Last, an empirical formula that can easily evaluate the mitigation effect of slag powder on the lateral deformation of piles is proposed and verified by the results of finite element analysis.