考虑应力历史及密实状态的漫滩相软土剪切强度研究  

Study on shear strength of flood plain soft soil considering stress history and density

作　　者：王军 崔志鹏 严刚 范玉梅 吴琪[3] Wang Jun;Cui Zhipengg;Yan Gang;Fan Yumei;Wu Qi(The Ist Geological Brigade of Jiangsu Geology and Mineral Exploration Bureau,Nanjing 210041,China;All Factor Testing Laboratory,Engineering Innovation Center for Urban Underground Space Exploration and Evaluation,Ministry of Natural Resources,Nanjing 210041,China;Institute of Geotechnical Engineering,Nanjing Tech University,Nanjing 210009,China)

机构地区：[1]江苏省地质矿产局第一地质大队,南京210041 [2]自然资源部城市地下空间探测评价工程技术创新中心全要素测试实验室,南京210041 [3]南京工业大学岩土工程研究所,南京210009

出　　处：《工程勘察》2023年第7期13-19,共7页Geotechnical Investigation & Surveying

基　　金：中国博士后科学基金项目(2021M690279);江苏省地质矿产科研项目(2019-KY-05)。

摘　　要：固结不排水抗剪强度是评价软土结构稳定性和地基承载力的重要参数。长江漫滩相软土具有含水率高、孔隙比大、压缩性高、灵敏度高、抗剪强度低等工程特性,为系统研究漫滩相软土的不排水剪切强度,对具有不同初始有效围压、固结度及孔隙比漫滩相软土开展了系列不排水三轴剪切试验。研究表明:各围压条件下不排水抗剪强度τ_(f)随孔隙比e的增大而降低,且降低速率逐渐减小,二者呈负幂函数关系,并建立了不同e条件下漫滩相软土的c和φ评价方法;τ_(f)随固结度U的增大而增大,并引入抗剪强度折减系数μ定量表征U对τ_(f)的影响。对比分析发现:三轴试验获取的τ_(f)与直剪试验获取的f具有强相关性,当U=1时,三轴试验获取的τ_(f)与直剪试验获取的τ_(f)基本一致;当U<1时,三轴试验获取的τ_(f)小于直剪试验获取的τ_(f),且随U的降低,两者的比例差异逐渐增大。Consolidated undrained shear strength is an important parameter to evaluate the structural stability of soft soil and the bearing capacity of the ground.The flood plain soft soil of Yangtze River has many engineering characteristics,such as high water content,large void ratio,high compressibility,high sensitivity,and low shear strength etc.In order to systematically study the undrained shear strength of flood plain soft soils,a series of undrained triaxial shear tests were carried out under different initial effective confining pressures,consolidation and void ratios.The study result shows that under each confining pressure condition,undrained shear strengthτ_(f) decreases with the void ratio e increases,and the decreasing rate gradually decreases,and the relationship between theτ_(f) and e is negative power function.In addition,the evaluation methods of c andφare established under different void ratio.The undrained shear strengthτ_(f) increases with the increase of consolidation degree U,and the shear strength reduction coefficientμis introduced to quantitatively descript the effect of U onτ_(f).The comparative analysis shows that theτ_(f) obtained by triaxial test has a strong correlation with theτ_(f) obtained by direct shear test,when U is 1,theτ_(f) obtained by the triaxial test is basically the same as theτ_(f) obtained by the direct shear test.When U is less than 1,theτ_(f) obtained by the triaxial test is smaller than that obtained by the direct shear test,and with the decrease of U,the difference between the two ratios gradually increased.

关 键 词：漫滩相软土 抗剪强度 固结度 孔隙比 折减系数 

分 类 号：TU41[建筑科学—岩土工程]