Dynamic centrifuge tests on liquefaction of clayey sand ground

The preparation, saturation and uniformity checking methods for clayey sand ground model are proposed. Then liquefaction model tests on clayey sand with clay content of 10% are performed by means of ZJU-400 geotechnical centrifuge shaking table, and the other model for clean sand with the same relative density is also performed for comparison. Seismic liquefaction phenomena of level ground are reproduced and the liquefaction characteristics of clayey sand ground are revealed. Measuring of bender elements shows that both models are uniformly prepared, and the shear wave velocity of the clayey sand is lower than that of the clean sand under the same condition. The permeability coefficient of the clayey sand is nearly an order of magnitude lower than that of the clean sand according to the test observations, which affects the responses of the excess pore water pressure (PWP) and stress-strain relationship during liquefaction. The difference of permeability results in slower buildup of PWP in the clayey sand at shallow depth but faster one at deep depth, while the post-liquefaction dissipation is 15 times longer than that of the clean sand. Response of shear stress-strain of the clayey sand is more pronounced than that of the clean sand at the liquefaction stage, and its secant modulus is smaller and the damping ratio is larger under post-liquefaction cyclic loadings. Model settlement mainly occurs during the process of PWP dissipation, and the clayey sand has longer dissipation time and doubles the settlement of the clean sand. This study presents scientific evidence for seismic response analysis and liquefaction evaluation of clayey sand ground.