均质黏土中桩靴基础贯入阻力系数Nc的解析解  

ANALYTICAL SOLUTION OF RESISTANCE FACTOR Nc FOR SPUDCAN FOUNDATION PENETRATING INTO UNIFORM UNDRAINED CLAY

作　　者：李大勇 王召龙 吴宇旗 LI Da-yong;WANG Zhao-ong;WU Yu-qi(College of Pipeline and Civil Engineering,China University of Petroleum(East China),Qingdao,Shandong 266580,China)

机构地区：[1]中国石油大学(华东)储运与建筑工程学院,山东青岛266580

出　　处：《工程力学》2025年第1期233-240,共8页Engineering Mechanics

基　　金：国家自然科学基金项目(51879044)。

摘　　要：自升式平台的桩靴基础需逐级预压入海床一定深度,使其承载力满足承受上部平台自重荷载及所受到的海洋环境荷载的要求。随着压入深度的增加,土体将绕过桩靴基础侧面逐渐回流至基础顶部。桩靴基础在不同压入深度处,土体的回流模式不同,导致基础的贯入阻力发生变化。考虑完全回流和不回流两种极端情况下的土体破坏模式,利用特征线法推导了桩靴基础贯入阻力系数N_(c),采用有限元极限分析法验证了计算模型的合理性。与已发表的文献中的离心机试验数据和数值模拟结果进行对比研究,验证了所提的理论方法的准确性。研究表明:光滑基底底部形成两个左右对称的弹性楔体,随着桩靴基础基底剪应力的增加,弹性楔体体积逐渐减小,当基底剪应力达到土体抗剪强度时,弹性楔体消失。贯入阻力系数N_(c)随着桩靴基础基底剪应力的增加呈线性增加,土体不回流情况下的贯入阻力系数比完全回流情况下的贯入阻力系数低约20%。Spudcan foundations are preloaded to penetrate into the seabed to provide sufficient bearing capacity to bear the vertical loads from the upper platform and the horizontal loads from ocean environments.A cavity will be formed above the foundation,which affects the penetration resistance of the spudcan foundation.The theoretical solution to the resistance factor N_(c) for spudcan foundation penetrating into clay was deduced based on the characteristic methods by considering two extreme conditions with and without fully localized back-flow.Meanwhile,finite element limit analyses(FELA)were conducted to verify the proposed failure mechanism of the spudcan foundation,and centrifuge tests and numerical simulations were used to verify the presented theoretical results.It is found that two failure wedges are formed below the base of the spudcan foundation,and its volume decreases with the increasing shear stress at the base of the spudcan foundation.Resistance factor N_(c) increases almost linearly with the increasing of the roughness factor between spudcan and soil.Facter N_(c) under the condition of no fully localized back-flow is 20%lower than that under the condition of fully localized back-flow.

关 键 词：桩靴基础 贯入阻力系数 解析解 均质黏土 破坏模式 

分 类 号：TU470[建筑科学—结构工程]