高动应力水平下软粘土动力特性研究及应用  

Research and application on dynamic characteristics of soft clay under high dynamic stress level

作　　者：王元战[1] 李世纪 雷继超 WANG Yuan-zhan;LI Shi-ji;LEI Ji-chao(National Key Laboratory of Water Conservancy Engineering Simulation and Security, Collaborative Innovation Center for Advanced Ship and Deep-Sea Exploration, Tianjin University,Tianjin 300072, China)

机构地区：[1]天津大学水利工程仿真与安全国家重点实验室,高新船舶与深海开发装备协同创新中心,天津300072

出　　处：《水道港口》2020年第1期99-106,共8页Journal of Waterway and Harbor

基　　金：国家重点研发计划(2016YFC0802204,2016YFC0802201);国家自然科学基金(51679166);国家自然科学基金创新研究群体科学基金(51321065);交通运输部交通建设科技项目(2014328224040)。

摘　　要：软粘土在受到不同应力水平动荷载作用时动力特性差异较大,在低水平动应力作用下土体强度呈现循环弱化并趋于稳定状态,在高水平动应力作用下土体强度会发生循环破坏,高、低动应力水平的临界值称为临界动应力。目前研究大多针对低水平动应力作用下土体强度循环弱化问题。针对烟台港淤泥质粉质粘土开展了一系列动三轴试验,探究淤泥质粉质粘土的临界动应力变化特性及土体在高水平动应力下的强度变化规律,研究了不同围压、不同固结静偏应力和不同超固结比条件下软粘土的动力特性。通过对动强度试验数据的统计分析,给出了土体临界动应力随固结围压的变化规律,得到了综合考虑循环次数、围压、静偏应力和超固结比的土体动强度模型。依据已有的低水平动应力下循环强度弱化模型和建立的高水平动应力下动强度模型,通过二次开发将其在ABAQUS软件中实现,建立了综合考虑不同动应力水平下土体强度循环弱化和循环破坏的有限元数值模型,并通过实例研究了土体强度循环破坏对地基承载力的影响。The dynamic characteristics of soft clay are different when subjected to different stress levels.Under the action of low level dynamic stress,the strength of the soil is weakened and tends to be stable.Under the action of high level dynamic stress,The soil will undergo cyclic failure.The critical value of the high and low dynamic stress levels is called the critical dynamic stress.At present,most of the researchers focus on the weakening of soil strength under low level dynamic stress.A series of dynamic triaxial tests were carried out on the silty clay of Yantai Port.The critical dynamic stress variation characteristics of silty clay and the strength variation of soil under high level dynamic stress were investigated.Dynamic properties of soft clay were studied under different confining pressures,drainage static stress and overconsolidation ratios.Through the statistical analysis of dynamic strength test data,the variation law of critical dynamic stress of soil with confining pressure is given,and the dynamic strength model considering cycle number,confining pressure,drainage static stress and over consolidation ratio is obtained.According to the realization of existing low-level dynamic stress strength weakening model and the high-level dynamic stress dynamic strength model established in ABAQUS software through secondary development,The finite element numerical model of cyclic weakening and cyclical failure under different dynamic stress levels is established.The influence of soil strength cyclic failure on foundation bearing capacity is studied by an example.

关 键 词：循环荷载 软土 动力特性 临界动应力 动强度模型 

分 类 号：U656[交通运输工程—港口、海岸及近海工程]