含细粒砂土反常剪切行为的数值模拟研究

发布时间：2018-01-09 13:22

本文关键词：含细粒砂土反常剪切行为的数值模拟研究　出处：《岩土力学》2015年S1期 　论文类型：期刊论文

【摘要】：针对含细颗粒砂土的反常剪切行为,开展了双轴剪切试验的数值模拟,从宏细观角度分析了其反常剪切行为发生的内在机制。数值模拟结果表明,增加围压能提高含细颗粒砂土的抗剪切液化能力,该反常行为的根本原因在于围压上升使得粗细颗粒更有效地参与了力链传递,增加了颗粒间的接触,增强了土体的密实度。细颗粒在土骨架中的移动对砂土的液化起着至关重要的作用,而粗颗粒仅起次要作用。研究表明,细颗粒在剪切过程中会持续从有效土骨架中移出成为无效颗粒,而部分粗颗粒也因失去细颗粒的支撑作用会脱离土骨架,直至试样最终液化。细颗粒一般参与土骨架中的弱力链,而粗颗粒则一般参与强力链,导致细颗粒较粗颗粒更容易在土骨架中移动。
[Abstract]:In view of the abnormal shear behavior of sand containing fine particles, the numerical simulation of biaxial shear test is carried out, and the internal mechanism of abnormal shear behavior is analyzed from the macro and meso view. The numerical simulation results show that the abnormal shear behavior occurs. The increase of confining pressure can improve the shear liquefaction resistance of sand with fine particles. The fundamental reason of this abnormal behavior is that the rise of confining pressure makes coarse particles participate in the force chain transfer more effectively and increase the contact between particles. The movement of fine particles in the soil skeleton plays an important role in the liquefaction of sand, while the coarse particles play only a secondary role. The fine particles will be continuously removed from the effective soil skeleton to become invalid particles during the shear process, and some coarse particles will be separated from the soil skeleton because of the loss of the supporting role of the fine particles. The fine particles generally participate in the weak force chain in the soil skeleton, while the coarse particles generally participate in the strong chain, which results in the fine particles moving in the soil skeleton more easily than the coarse particles.
【作者单位】：中山大学岩土工程与信息技术研究中心;香港大学土木系;
【基金】：国家自然科学基金(No.51209237,No.51428901)
【分类号】：TU441
【正文快照】： 1引言砂土液化导致了许多的岩土工程事故和灾害。大量的事故现场调查表明,发生液化的砂土常含有一些粒径小于0.075 mm的细颗粒[1-5]。这些细颗粒的存在使得砂土的剪切液化行为变得非常复杂。Yamamuro等[6]和Thevanayagam等[7]通过室内普通三轴试验发现,含细颗砂土的剪切行为较

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