黏土中吸力式桶形破坏包络面数值模拟研究

陈佳莹　滕竟成　吴则祥

摘 要：為了应用高级土体本构对黏土中的吸力桶基础进行完整的有限元模拟，以建立吸力桶基础的破坏包络面，利用有限元方法分析了在不同单调组合荷载作用下固结黏土中的吸力桶基础离心机试验，对比试验结果验证了使用硬化土（HS）本构模型的有效性;通过径向滑移试验进行了大量的有限元分析，进一步研究了竖向力（V）水平力（H）弯矩（M）空间的破坏模式。在此基础上描述了H-M平面、V-H平面以及V-H-M空间的破坏包络面。结果表明，H-M破坏包络面类似于倾斜的椭圆;不同竖向荷载对H-M破坏包络面倾斜度的影响可以忽略;H-M破坏包络面的尺寸随着竖向荷载值的增加而减小;竖向荷载和水平荷载之间存在很强的相互影响，即竖向承载力和水平承载力构成的V-H屈服面近似为1/4椭圆，可以看出，H-M倾斜椭圆的大小由竖向荷载控制。基于数值模拟结果提出了在V-H-M空间中表达三维破坏包络面的解析式。

关键词：桶式基础;破坏包络面;黏土;有限元法;循环荷载;宏单元

中图分类号：TU442;TU476 文献标志码：A 文章编号：2096-6717（2022）04-0045-07

Numerical modelling of failure envelope for suction bucket foundation in clay

CHEN Jiaying1， TENG Jingcheng2， WU Zexiang3

（1. CCCC Third Harbor Consultants Co.， Ltd， Shanghai 200032， P. R. China; 2. Department of Civil and Environmental Engineering， The Hong Kong Polytechnic University， Hong Kong， P. R. China; 3. College of Civil Engineering and Architecture， Wenzhou University， Wenzhou 325000， Zhejiang， P. R. China）

Abstract： The purpose of this study is to perform a complete finite element （FE） simulation of the suction bucket foundation in clay using advanced soil constitutive model to establish the failure envelope of the suction bucket foundation. Firstly， the Hardening Soil （HS） model is used to analyse the centrifuge tests of suction bucket foundation in normally consolidated clay under different monotonic combined loadings by FE method. The comparisons between testing and simulated results verify the effectiveness of the FE analysis using the HS model. Then， a large number of FE analysis is performed by radial swipe tests， and further extended to the failure mode of V-H-M （vertical force-horizontal force-bending moment） space. Based on this， the failure envelope on the H-M plane， the V-H plane， and the three-dimensional failure envelope surface in the V-H-M space are described. The results show that the H-M failure envelope is similar to an inclined ellipse; the effect of vertical load on the inclination of the H-M failure envelope can be ignored; the size of the H-M failure envelope decreases with the increase of the vertical load; there is a strong interaction between vertical and horizontal loads， i.e.， the V-H yield surface formed by vertical and horizontal bearing capacity is approximately a quarter ellipse. It can be seen that the size of the H-M inclined ellipse is controlled by the vertical load. Based on all these results of numerical simulations， a new analytical expression is finally proposed to represent the three-dimensional failure envelope of the suction bucket foundation in V-H-M space.

Keywords：caisson foundation; failure envelope; clay; finite element method; cyclic loading; macro-element

吸力桶是一种顶部封闭的圆柱形管，它被沉到海底并压入海床，允许海洋沉积土在自重作用下进入，同时将水从其顶部抽出，以产生将其推至足够深度的吸力。其可安装至不同的海底深度，且方便回收，在海洋基础中得到广泛应用[1-4]。然而，要优化其设计，必须了解吸力桶基础的性能。关于组合荷载下吸力桶土相互作用的试验研究可分为3类：现场实验[5]、室内模型试验[6-7]、离心机试验[8-9]。……