准确评估沉垫基础在黏土海床上的竖向承载力对自升式平台沉垫基础在海洋环境中的安全作业具有重要意义.结合离心机试验与欧拉-拉格朗日法(CEL)大变形数值计算方法研究沉垫基础在水平和斜坡黏土海床上的竖向承载特性,首先通过T-bar贯入试验得到土体的不排水抗剪强度沿深度的分布规律,然后进行两种底面形状的沉垫基础在软黏土海床上的竖向承载特性离心机试验,最后结合CEL大变形数值方法对沉垫基础的竖向承载特性进行探讨,分析沉垫基础在不同坡度海床上的承载力和土体位移变化.研究结果表明,沉垫基础荷载-位移曲线没有明显峰值,正方形基础承载力略高于长方形基础;在基础入泥过程中,土体超孔压发展规律与荷载-位移曲线的变化规律基本一致,竖向荷载大部分由超孔压承担;随着海床坡度增大基础承载力逐渐减小且基础底部土体有向坡角方向滑移的趋势,可能导致海床发生滑移破坏,工程中应尽量避免在坡度较大的海床区域作业.

Accurate evaluation of the vertical bearing capacity of the mat foundation on the clay seabed is of great significance for the safe operation of the mat-supported jack-up platform in the marine environment. Combining the centrifuge test and the coupled Eulerian-Lagrangin (CEL) large deformation numerical calculation method, the vertical bearing characteristics of mat foundation on horizontal and sloping clay seabed were studied. First, the distribution law of undrained shear strength of soil along the depth was obtained through the T-bar penetration test. Then, the vertical bearing characteristics of two kinds of bottom mat foundations on soft clay seabed were tested. Finally, the vertical bearing characteristics of the mat foundation were discussed in combination with the numerical method of CEL large deformation, and the bearing capacity and soil displacement changes of the foundation on different inclination seabed were analyzed. The results show that the foundation load displacement curve has no obvious peak value, and the bearing capacity of the square foundation is slightly higher than that of the rectangular foundation. The development law of soil excess pore pressure is basically consistent with the change law of bearing capacity in the process of foundation entering the sea bead, and most of the vertical stress is borne by the excess pore pressure. The foundation bearing capacity gradually decreases as the slope of the seabed increases, and the soil below the foundation tends to slip in the direction of the slope angle, which may lead to slip damage of the seabed. Therefore, operation in the seabed area with a large slope should be avoided in actual practice.