硬土-软土插桩过程数值分析及验证  

Numerical analysis and verification of pile penetration into stiff-over-soft clay

作　　者：张建[1] 唐文献[1] 苏世杰[1] 秦文龙[1] 王静芳[1] 刘仁昌 

机构地区：[1]江苏科技大学 [2]烟台中集来福士海洋工程有限公司

出　　处：《石油勘探与开发》2013年第4期492-496,共5页Petroleum Exploration and Development

基　　金：国家自然科学基金项目(51005108);江苏省"六大人才高峰"项目(2011A031)

摘　　要：基于Hossain M S的土工离心模型试验,建立自升式平台插桩过程的数值模型,根据数值计算结果分析插桩过程中土壤流动特性以及插桩深度与插桩阻力的关系,并首次对桩靴底部压力分布规律进行研究。利用Hossain M S的试验结果对数值模型进行了验证,数值解与试验值吻合程度较好,说明模型可靠。数值计算结果表明:插桩过程中发生了硬土表面局部隆起、硬土-软土界面变形、空腔形成、土壤回流等现象;硬土、软土的强度比越小,桩靴下方硬土块体积越小,桩靴上方硬土分布越连续、均匀,空腔深度越大;土壤重度越大,桩靴上方硬土回流量越大,空腔深度越小,土壤重度对桩靴下方硬土块形状和体积几乎没有影响;硬土软土的强度比越大、有效重度比越小,发生"刺穿"的可能性越高。桩靴底部压力由内向外先增大、后减小、再增大,证明《海上移动平台入级与建造规范》中桩靴底部压力的线性分布假设与实际不符。A numerical model for jack-up penetration process was built based on the geotechnical centrifugal model test by Hossain M S. The soil flow mechanism and the relationship between penetration depth and penetration resistance were analyzed based on numerical results. The distribution pattern of the spudcan bottom pressure was investigated for the first time. The numerical results are in good agreement with Hossain M S experimental results, which indicates that the proposed model is reliable. The numerical results show that, soil flow failures, such as surface and interface swelling, cavity formation, and soil backflow, happen in the penetration process; the lower the strength ratio between stiff and soft clay is, the smaller the volume of stiff block under the spudcan is, the more continuous and uniform the stiff clay distribution above the spudcan is, and the deeper the cavity is. The higher the soil unit weight, the more the backflow stiff soil above the spudcan and the shallower the cavity. The soil unit weight has almost no effect on the stiff soil shape and volume under spudcan. The higher the strength ratio between stiff and soft clay or the lower the soil unit weight is, the more likely the punch-through OCCULTS. The bottom pressure first increase, then decrease, and increase sharply, from inside to outside, which proves that the linear assumption of the spudcan bottom pressure in ＇Rules for Mobile Offshore Drilling Units＇ does not conform to the fact.

关 键 词：自升式平台 插桩过程 数值模型 桩靴承载力 桩靴底部压力 

分 类 号：TU411[建筑科学—岩土工程]