﻿ 多种自升式海洋平台桩靴上拔过程仿真分析
 舰船科学技术  2018, Vol. 40 Issue (8): 66-70 PDF

Simulation of the pull-up process of several self-elevating offshore platform pile boots
LI Yong-zheng, SUN Xiao-peng, XIE Ren-jie, TANG Yan-bin, WANG Zhe, LI Chen-peng, BIAN Chao
School of Naval Architecture and Ocean Engineering, Jiangsu University of Science and Technology, Zhenjiang 212003, China
Abstract: In this paper, using Ansys Workbench Design Modeler to establish pile shoe and soil models as main research object. Then simulating the pile shoe pulling process byLS-DYNA. And calculate three kinds of Pile-pulling force and the deformation of soils during the three pile-jacking process. Then compare the theoretical calculation value of pile-up resistance with the result of numerical simulation and analyze. This article has a certain engineering significance for the development of offshore platforms in the future.
Key words: jack-up platform     pile boots     pull-out resistance
0 引　言

1 圆形桩靴上拔力数值模拟 1.1 桩靴与土模型

 图 1 拔桩模型 Fig. 1 Pulling pile model
1.2 模型参数设置

1.3 边界条件设置及接触

1.4 计算结果分析

 图 2 桩靴上拔力与上拔时间相互关系 Fig. 2 Relationship between pull-out force and pull-up time of pile shoes

 图 3 土体位移和桩靴上拔时刻关系 Fig. 3 Relationship between soil displacement and pulling time of pile shoes

1.5 不同时刻拔桩土体流动机制分析

 图 4 不同时刻土体流动情况 Fig. 4 Soil flow at different Times

2 不同桩靴形式对桩靴上拔力影响研究 2.1 桩靴与土模型

 图 5 三种桩靴形式几何模型和数值模型 Fig. 5 Geometric model and numerical model ofthree kinds of pile shoes
2.2 计算结果分析

3种桩靴上拔过程中相同时刻上拔力对比如表3所示。

 图 6 三种桩靴形式上拔力与上拔时间关系 Fig. 6 Relationship between upper pull-out time and pull-out time of three kinds of pile shoes

 图 7 三种桩靴形式土体位移与上拔时间相互关系 Fig. 7 Relationship between soil displacement and pull-up time in the form of three kinds of pile shoes

2.3 不同桩靴形式土体流动机制分析

 图 8 8.998 2 s时刻2种桩靴形式周围土体变化情况 Fig. 8 Changes of soil around the two pile shoes at 8.998 2 s

 图 9 38 s时刻2种桩靴形式周围土体变化 Fig. 9 Changes of soil around the two pile shoes at 38 s

 图 10 41.999 s时刻3种桩靴形式周围土体变化 Fig. 10 Changes of soil around the form of three pile shoes at 41.999 s

3 桩靴上拔阻力理论计算值与数值模拟结果比较

 ${F_u} = {N_c}{c_u}A + {A_s}{f_s} + {W_g}\text{。}$

3种桩靴理论计算结果和数值模拟结果如表4所示。

4 结　语

1）通过对圆形桩靴与土体之间的模型分析，得知在桩靴上拔过程中，土体的变形主要发生的桩靴周围，远离桩靴的土体基本不发生变形。此外，通过研究桩靴上拔时刻与土体位移的关系，得知拔桩阻力会随着速度的增大而增大。

2）通过计算、对比分析圆形桩靴、六边形桩靴、十二边形桩靴上拔过程中所需要的上拔力，得知圆形桩靴临界上拔力最大，其次是十二边形桩靴，六边形桩靴最小。由此可知，桩靴上拔力随着接触面和侧表面接触面积的增大而增加。

3）采用公式Fu=NccuA+Asfs+Wg所计算的桩靴上拔力和LS-DYNA数值模拟的拔桩力进行比较，得知相对其他2种桩靴，圆形桩靴计算的理论值与数值模拟的差值更小，更接近实际情况。

 [1] 李润培, 王志农. 海洋平台强度分析[M]. 上海: 上海交通大学出版社, 1992. [2] 孙雅楠. 自升式海洋平台桩靴强度分析[D]. 大连: 大连理工大学, 2013. [3] 任宪刚, 白勇. 精确模拟土壤反力对桩靴性能影响的研究[J]. 船舶力学, 2012, 16(1): 146–155. http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=cblx201201017 [4] 唐文献, 秦文龙, 张建等. 自升式平台桩靴结构优化设计[J]. 中国造船, 2013(3): 78–84. http://www.cqvip.com/QK/98196A/201611/668613778.html [5] 陈佳欣. 自升式平台2种典型桩靴结构形式对比[J]. 船海工程, 2016, 45(5): 146–150. http://www.cnki.com.cn/Article/CJFDTotal-CANB2011S1021.htm [6] 高畅, 曲健冰, 李红涛. 三桩腿自升式平台拔桩作业有限元计算方法研究[J]. 中国海洋平台, 2016, 31(2): 75–81. http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=zghypt201602011 [7] KELLEZI L, STROMANN H. FEM analysis of jack-up Spudcan penetration for multi-layered critical soil conditions [C]//Dundee, Scotland: the BGA (British Geotechnical Association) International Conference on Foundations (ICOF), 2003: 411–420. [8] KELLEZI L, HOFSTEDE H, HANSEN P B. Jack-up footing penetration and fixity analyses [J]. Proc. ISFOG, 2005: 559–565. [9] KELLEZI L, DENVER H, KUDSK G, et al. FE skirted footings analyses for combined loading and layered soil profile [C]//Madrid: The 14th European conf. On Soil Mech. and Geotechnical Eng, 2007(2): 35–38. [10] KELLEZI L, KUDSK G, HOFSTEDE H. Skirted footings capacity for combined loads and layered soil conditions[C]//Dundee, Scotland, IHS BRE Press: the BGA(British Geotechnical Association) International Conference on Foundations, 2008(3): 24–27. [11] KELLEZI L, KUDSK G, HOFSTEDE H. Jack-up rig foundation design applying 3d fe structure-soil-interaction modeling[C]//Dundee, Scotland, IHS BRE Press: the BGA(British Geotechnical Association) International Conference on Foundations, 2008(3): 24–27. [12] KOHAN O, BIENEN B, GAUDIN C, et al. The effect of water jetting on Spudcan extraction from deep embedment in soft clay[J]. Ocean Engineering, 2015, 97: 90–99. [13] PURWANA O A, LEUNG C F, CHOW Y K, et al. Influence of base suction on extraction of jack-up Spudcans[J]. Geotechnique, 2005, 55(10): 741–754.