Research on penetration characteristics of suction foundation based on seepage in sand

The suction foundation (SF) has significant resistance reduction effect due to the seepage effect under the suction-assisted penetration. Seepage is an important factor in resistance reduction. In this paper, the model experiments and numerical simulation method were employed to analyze the resistance of suction-assisted penetration in sand. By analyzing the mechanism of resistance reduction, a suction foundation for enhancing seepage (SFES) has been proposed. The SFES was installed the degradable material inside the SF. The size of the degradable materials is smaller than the inner diameter of the foundation. During suction-assisted penetration, water suddenly contracts inside the foundation, resulting in a decrease in excess pore pressure on the inner side of the foundation and ultimately reducing installation resistance. The coefficient of evaluating the change of penetration resistance under seepage action was put forward. The results had shown that the pore water pressure of the sandy soil near foundation wall was reduced by the sudden contraction during the suction-assisted penetration, which was more conducive to resistance reduction. Under the same penetration depth, the inner resistance of the SFES change coefficient was 8.4 %-25.9 % smaller than that of SF. When the relative penetration depth $h/D\ge 0.25$, the area of piping ($\zeta \ge 1$) region within SFES was smaller than that of SF. As$h/D=0.9$, the area of piping ($\zeta \ge 1$) region within SFES producing piping was 27.9 % less than SF. The SFES had more advantages in the suction-assisted penetration.