波浪荷载作用下软黏土软化模型研究

付培帅1， 唐小微1， 韩小凯1， 刘功勋2

(1.大连理工大学 海岸和近海工程国家重点实验室，辽宁 大连116023；

2.中交上海航道勘察设计研究院有限公司 中交疏浚技术重点实验室，上海200120)

摘要：波浪荷载能引起海床土体的主应力轴连续旋转。不同于地震、交通等循环荷载，在周期性波浪荷载作用的土体应力路径方式下，软黏土的软化效用更为明显。本文分别对天然和扰动的海床土体在波浪荷载作用下的应力响应进行模拟，并分析应力路径的特点；为描述软化后的应力-应变关系，将软化效用和累积塑性应变的参数引入到能够反应土体动力非线性的Hardin-Drnevich模型中，建立修正模型，使之能够反应软黏土体软化与塑性应变累计特性；通过与模拟波浪荷载下土体应力特征的循环耦合试验结果进行对比分析，验证该修正模型的可靠性。

关键词：波浪荷载； 应力路径； Hardin-Drnevich模型； 软化

收稿日期：*2014-08-20

基金项目：“九七三”国家重点基础研究发展计划项目(NO.2011CB013605-2)；国家高技术研究发展计划863项目(NO. 2012AA112510)

作者简介：付培帅(1988-)，男，河南人，硕士，主要从事海洋土力学及地下结构抗震研究.E-mail：fupeishuai5@163.cn

中图分类号:TU43文献标志码：B

DOI:10.3969/j.issn.1000-0844.2015.01.0027

Research on Softening Model of Soft Clay under Wave Load

FU Pei-shuai1， TANG Xiao-wei1， HAN Xiao-kai1， LIU Gong-xun2

(1.StateKeyLaboratoryofCoastalandOffshoreEngineering，DalianUniversityofTechnology，Dalian，Liaoning116023,China；

2.KeyLab.OfDredgingTechnologyofCCGRP，ShanghaiWaterwayEngineeringDesign

andConsultingCo.Ltd.ofCCGRP，Shanghai200120，China)

Abstract：Wave load causes continuous rotation of the principal stress axes of seabed soil.Unlike seismic load and traffic load，under the action of cyclical wave load，stiffness softening of soft clay is much more obvious.Numerical simulation is applied to obtain the stress response of undisturbed and disturbed seabed soil，and to analyze the characteristics of the stress path.Under wave loads，the main feature of the seabed soil is the continuous rotation of its maximum principal stress axis；the maximum principal stress’ cycle is similar to the wave load cycles.Under the influence of the structure in the seabed disturbance，the soil’s stress path changed under the wave load，and the factors that affect the stress path can be generalized using the initial principal stress orientation，the initial stress ratio，the angle of the major principal stress direction，and other factors.To describe the relation of a soil’s stress and strain after stiffness softening，two parameters were introduced to the Haridin-Drnevich model to reflect the stiffness softening and cumulative plastic strain phenomenon，and these two parameters are a function of the soil’s initial status，which influences its stress path under wave load.The cyclic coupling shear tests can probably simulate the wave load and therefore，this modified Haridin-Drnevich model should be compared with the results of cyclic coupling shear tests where wave loads can be applied to verify its reliability.

Key words： wave load； stress path； Haridin-Drnevich model； softening

0引言

随着经济社会的快速发展，城市轨道交通、导堤、海上钻进平台、码头、人工岛、高铁等工程项目不可避免地建设在软黏土或含有软黏土土层上。当这类土工结构物承受交通、地震、海风、波浪等动力循环荷载时，其力学性质与静力作用截然不同。例如我国最大的水运工程项目长江口导堤建设工程，由于遭受到强风暴的袭击，导堤试验段的部分沉箱在建造期间有的沉入土中达数米之深，有的偏移原始位置大约20 m之远[1]。……