海上自升式钻井平台拔桩阶段桩靴上拔阻力的机理研究

Mechanism Study on Spudcan Uplift Resistance of Offshore Jack-up Drilling Platform During the Process of Extraction

在桩靴上拔分析中,提出了将上拔阻力分为桩靴上部阻力和桩靴底部吸力的概念,通过数值模型模拟了多种加载条件和不同桩靴贯入深度时桩靴周围孔压的消散规律和桩靴上拔阻力不同组成部分的变化规律,证明了这种概念的可行性和准确性;在此基础上,确立了桩靴在不同贯入深度上拔时土体不同的破坏模式,给出了桩靴底部吸力在平台工作荷载、上拔速度和贯入深度等参数变化时的发展规律,数值模拟的吸力变化范围在总上拔阻力的27%～80%,极限上拔阻力系数为12.62,这为平台上拔能力储备和桩靴底部环喷系统的准确设计提供理论依据.

In the analysis of extracting spudcan,the conception of the uplift resistance divided into upper resistance and base suction was presented,which was proved to be feasible and accurate by the numerical models carried out to evaluate pore pressure changes in the soil around spudcan and uplift resistance of spudcan for different soil and work-ing load conditions during extraction in different embedded depths.Based on the new conception,the soil failure modes for different depths of embedded spudcan during extraction were derived and the pattern in which the magni-tude of base suction changes with operation period and magnitude of working load,uplift velocity and depth of em-bedded spudcan was revealed,which shows the range of base suction is 27%—80% of uplift resistance,and the limit-ing uplift resistance coefficient is 12.62.Thus the results have provided theoretical basis for designing the uplift capac-ity and jetting system of spudcan base in engineering.