Seismic responses of pipe piles improved with cement-treated soil in sand

To reveal the effects of cement-treated soil reinforcement on the seismic resistance of precast concrete pipe piles, the shaking table tests on pipe-pile groups improved with cement-treated soil in liquefiable sand are carried out. The results illustrate that the excess pore pressure ratios of soils around the piles are reduced by about 23.3% due to the cement-treated soil reinforcement. Before liquefaction, the acceleration responses of the soils around the piles improved with cement-treated soil are lower than those the in pipe piles. However, the attenuation of acceleration in the pipe pile tests is more obvious after soil liquefaction. The lateral displacement of the pile-head and the settlement of the raft in case of the pipe piles improved with cement-treated soil are greatly reduced due to the presence of cement-treated soil. Moreover, the larger the depth of cement-treated soil, the more significant the decrease in lateral displacement and settlement. The cement-treated soil can effectively restrain the increase of bending moment of the piles in the range of cement-treated depth. However, the location of the maximum moment in the piles is different under various depths of cement-treated soil.