›› 2018, Vol. 39 ›› Issue (9): 3285-3293.doi: 10.16285/j.rsm.2016.2870

• 基础理论与实验研究 • 上一篇    下一篇

软黏土中吸力锚循环失稳过程的模型试验

程星磊1, 2,王建华1,王哲学1   

  1. 1. 天津大学 水利工程仿真与安全国家重点实验室,天津 300072;2. 天津城建大学 天津市软土特性与工程环境重点实验室,天津 300384
  • 收稿日期:2016-12-06 出版日期:2018-09-11 发布日期:2018-10-08
  • 通讯作者: 王建华,男,1955年生,博士,教授,博士生导师,主要从事土动力学与海洋岩土工程方面的研究工作。E-mail: tdwjh@tju.edu.cn E-mail: chengxinglei110@163.com
  • 作者简介:程星磊,男,1987年生,博士研究生,主要从事土的动力特性及本构关系方面的研究工作。
  • 基金资助:

    国家自然科学基金项目(No.51579174);天津市高等学校基本科研业务费资助项目(No.2016CJ04,No.2016CJ01)

Model experiment on cyclic instability process of suction anchors in soft clays

CHENG Xing-lei1, 2, WANG Jian-hua1, WANG Zhe-xue1   

  1. 1. State Key Laboratory of Hydraulic Engineering Simulation and Safety, Tianjin University, Tianjin 300072, China; 2. Key Laboratory of Soft Soil Engineering Character and Engineering Environment of Tianjin, Tianjin Chengjian University, Tianjin 300384, China
  • Received:2016-12-06 Online:2018-09-11 Published:2018-10-08
  • Supported by:

    This work was supported by the National Natural Science Foundation of China (51579174) and the Fundamental Research Funds for the Universities in Tianjin City (2016CJ04, 2016CJ01).

摘要: 开展了张紧式吸力锚在侧壁最优系泊点处遭受平均荷载和循环荷载共同作用下的模型试验,着重研究了软黏土中吸力锚在等幅及变幅循环荷载下的变形失稳过程。研究发现,循环累积位移过大是锚发生破坏的主要原因。对于等幅循环加载试验,由于竖向附加荷重的施加,锚在水平向的循环累积位移要明显大于竖向,表现为明显的水平破坏模式。在特定的平均荷载水平下,循环荷载水平越高,锚的累积位移发展得越快,达到破坏所需的循环次数就越少。循环位移随循环次数的增长变化不明显,但随循环荷载水平的增大而增大。对于变幅循环加载试验,系泊点各方向的循环累积位移与循环位移均与循环荷载水平成正比。不同的循环加载时程下,锚的竖向累积位移均比水平累积位移大,表现为偏向于竖向破坏的中间破坏模式。锚前期的循环加载历史对后续加载产生的累积变形有明显影响。与静力加载相比,循环加载时锚的运动方向角有所增大,这可能是由于锚底孔压的累积要大于锚侧孔压的累积,从有效应力的角度分析,锚底有效应力的减少相对锚侧明显,进而使得锚竖向承载力减小得更多,导致锚的竖向运动更明显。

关键词: 吸力锚, 模型试验, 循环荷载, 循环变形, 软黏土

Abstract: Model tests of the suction anchors with taut mooring systems are conducted under combined average and cyclic loads at the optimal loading point on the side wall of anchors. The deformation instability process of suction anchor subjected to constant and variable amplitude cyclic loads are investigated. It is found that too large cyclic accumulative displacement is the main reason for the failure of anchor. The cyclic accumulative displacement of anchor in the horizontal direction is larger than that in the vertical direction due to application of the vertical additional loads, so the horizontal failure of suction anchors occurs for the constant amplitude cyclic loading tests. The accumulative displacement increases faster with higher cyclic load level at a given average load level, and the number of cycles to failure becomes less. The cyclic displacement does not change obviously with the increase of the number of cycles, but increases with the increase of cyclic load level. The cyclic accumulative displacement and cyclic displacement in each direction at the mooring point increase with the increase of cyclic load level for variable amplitude cyclic loading tests. The accumulative displacements are larger in vertical than in horizontal under different cyclic loading time histories, so the moderate preferring vertical failures of anchors occur. Besides, the previous cyclic loading histories have an obvious influence on the accumulative deformation produced by subsequent loading. Compared with the static loading, the movement direction angle of the anchor under cyclic loading increases, which may be due to the greater accumulation of pore pressure at the bottom of the anchor than that at the side wall. From the view of effective stress, the decrease of effective stress at the bottom is relative obvious than that at the side wall, thus vertical bearing capacity decreases more remarkably, and vertical movement of anchor is more obvious.

Key words: suction anchors, model tests, cyclic loads, cyclic deformation, soft clays

中图分类号: 

  • TU 443
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