基于FLAC^3D的自升式平台地基承载力数值模拟

Numerical Analysis on Bearing Capacity of Foundation for Jack-up Platform Based on FLAC^3D

自升式平台的稳定性分析中,插桩作业的地基承载力分析极为重要。以舟山某自升式平台为研究对象,采用理论计算和数值模拟的方法对插桩作业的地基承载力及插桩速度进行了分析研究。首先,采用《海洋井场调查规范》和SNAME规范计算不同插桩深度的地基承载力,得到最佳插桩深度为14 m。其次,采用FLAC^3D数值模拟,研究插桩速度对地基承载力的影响。结果表明,当贯入速度大于0.1 mm/s时,贯入速度越大,得到的极限承载力越大,Q-s曲线有明显的峰值点;当贯入速度为0.01 mm/s^0.1 mm/s时,Q-s曲线无明显峰值点,呈现较为稳定的趋势;而当贯入速度小于0.01 mm/s时,Q-s曲线趋于稳定,接近准静态过程。基于0.01 mm/s的插桩速度,数值模拟得到的插桩深度为12 m。

The bearing capacity analysis during the installation of piles of platform is extremely important for the stability analysis of the Jack-up platform.In this paper,theoretical analysis and numerical simulations were carried out to analyse the foundation stability and the effect of the pile penetration rate on the bearing capacity of foundation for the Jack-up platform in Zhoushan.Firstly,the bearing capacity of the foundation at different depths of pile was calculated using the Specification for Marine Well Site Survey and SNAME.Results show that the optimal depth is 14 m.Secondly,the effect of penetration rate on bearing capacity of foundation was studied by FLAC^3D numerical simulations.The results show that when penetration rate is greater than 0.1 mm/s,there is a peak value on the Q-s curve and the bearing capacity of the foundation increases as the penetration rate increases;When the penetration rate is between 0.01 mm/s and 0.1 mm/s,there is no peak value on the Q-s curve;When the penetration rate is lower than0.01 mm/s,the Q-s curve tends to be stable.Based on a penetration rate of 0.01 mm/s,the depth of pile calculated from numerical simulation is 12 m.