循环荷载作用下海洋软土动力特性数值模拟研究  

Numerical Simulation Study on Dynamic Characteristic of Marine Soft Soil under Cyclic Shear

作　　者：郝李坤 石崇[1,2] 单志钢 刘宁 陈晓[1,2] HAO Likun;SHI Chong;SHAN Zhigang;LIU Ning;CHEN Xiao(Key Laboratory of Ministry of Education for Geomechanics&Embankment Engineering,Hohai Univ.,Nanjing 210024,China;Research Institute of Geotechnical Engineering,Hohai Univ.,Nanjing 210098,China;Power China Hua Dong Engineering Corporation,Hangzhou 311122,China)

机构地区：[1]河海大学岩石力学与堤坝工程教育部重点实验室,南京210024 [2]河海大学岩土工程科学研究所,南京210098 [3]中国电建集团华东勘测设计研究院有限公司,浙江杭州311122

出　　处：《三峡大学学报（自然科学版）》2021年第5期6-12,共7页Journal of China Three Gorges University：Natural Sciences

基　　金：国家自然科学基金面上项目(51679071);国家重点基础研究发展计划(2018YFC1508501)。

摘　　要：在海浪长期循环冲击的作用下,海洋土体材料的力学特性和变形机制往往与静荷载作用下的不同.基于典型海洋土物理及力学特性试验,运用离散元方法建立数值模型,标定土体细观参数,进行直接剪切数值试验和双轴压缩循环加卸载数值试验.研究结果表明:循环加载初期,试样的主要位移形式呈中心对称形态,最大位移发生在试样的4个棱角处,随着循环加载次数增加,试样的位移由竖向的中心轴线向两侧扩展;在循环单剪试验中,随着循环幅值的不断增大,滞回圈不断变大,塑性应变不断累积,在剪切位移只有1 mm时,能量损失较小,试样的变形基本属于弹性变形,随着剪切位移的增加,试样的塑性变形增加,能量损失增加;发生X型剪切破坏时,试样内部沿着120°方向的裂纹带发生错动,在低围压的情况下,试样X型剪切错动现象更显著,试样的剪胀效应更明显.随着围压增加,试样的剪切强度上升,试样的破坏应变减小.研究成果可为海洋软土力学特性研究提供参考.Under the long-term cyclic impact of ocean waves,the mechanical properties and deformation mechanisms of marine soil materials are different from those under static loads.Based on the physical and mechanical characteristic tests of typical marine soils,the discrete element method was used to construct a numerical model,calibrate the microscopic parameters of the soil,and carry out direct shear numerical experiments and biaxial compression cycle load-unload numerical experiments.The results show that at the initial stage of cyclic loading,the main displacement of the sample is center-symmetrical.The maximum displacement occurs at the four corners of the sample.As the times of cyclic loading increases,the displacement of the sample expands from the vertical central axis to sides.In the cyclic simple shear test,as the cyclic amplitude increases,the hysteresis loop becomes larger and the plastic strain accumulates.When the shear displacement is 1mm,the energy loss is small,and the deformation of the sample is basically elastic deformation.As the shear displacement increases,the plastic deformation of the specimen increases,and the energy loss increases.When the X-shaped shear failure occurs,the shear bands appear along the 120°direction inside the specimen.Under lower confining pressure,the shear dilatancy effect of the specimen is more obvious.With the increase of confining pressure,the shear strength increases,and the failure strain of the specimen decreases.The research results can provide reference for the research on the mechanical properties of marine soft soil.

关 键 词：海洋软土 颗粒离散元 循环荷载 动力特性 

分 类 号：TV16[水利工程]