一个基于微观界面滑移效应的纤维加筋砂土抗剪强度理论模型  

A THEORETICAL MODEL OF SHEAR STRENGTH FOR FIBER-REINFORCED SANDY SOIL BASED THE MICRO INTERFACE SLIP EFFECT

作　　者：冯德銮 肖雪莉 梁仕华[1] FENG Deluan;XIAO Xueli;LIANG Shihua(School of Civil and Transportation Engineering,Guangdong University of Technology,Guangzhou 510006,China)

机构地区：[1]广东工业大学土木与交通工程学院,广州510006

出　　处：《工业建筑》2021年第10期147-156,140,共11页Industrial Construction

基　　金：国家自然科学基金项目(52078142);广东省自然科学基金项目(2017A030310244)。

摘　　要：纤维加筋土是一种复杂的多相复合材料,其强度由内部多相物质的物性以及不同相物质间的耦合力学响应机制共同决定。为考虑纤维几何特征和力学特性对纤维加筋砂土抗剪强度的影响,根据砂颗粒之间以及砂颗粒与纤维之间相互作用产生的微观界面滑移效应,划分纤维加筋砂土的物质相以构造反映其内部材料特征信息的纤维加筋砂土细观胞元。基于细观胞元内部纤维与砂颗粒集合体两相材料间的微细观变形协调条件,结合可有效描述力学响应界面不连续性的应变梯度理论,导出基于细观物理机制的纤维加筋砂土强度理论模型。采用Michalowski-Cermak的纤维加筋砂土三轴固结不排水剪切试验结果对纤维加筋砂土细观胞元模型进行验证,结果表明该模型能有效地模拟和预测纤维加筋砂土的屈服强度。纤维掺入诱发其邻近砂颗粒集合体产生塑性转动梯度和摩擦界面滑移,是纤维加筋砂土纤维强化效应的细观物理机制。Fiber-reinforced sandy soil is a multi-phase and multi-scale geo-material,and its strength is determined by properties of the heterogeneous materials of soil and their coupling interaction mechanical responses. On the basis of the microscopic slip effect between sand grains and between sand grains and fibers,a soil cell-element that could describe the internal material information and fiber characteristics of fiber-reinforced sandy soil was constructed by dividing fiber-reinforced sandy soil into different phases of materials to study the influence of the geometrical and mechanical characteristics of fibers on the shear strength of fiber-reinforced sandy soil. According to the compatible geometry deformation between fibers and soil on the microscale,the notion of strain gradient that could effectively describe the interface discontinuity of mechanical response was introduced,and a theoretical model of fiber-reinforced sandy soil based on mesophysical mechanisms was proposed. Moreover,the results from consolidated-undrained triaxial tests conducted by Michalowski and Cermak were used to validate the proposed model. Meanwhile,the theoretical parameters of the model were quantitatively studied. The results showed the addition of fibers caused plastic rotation gradient and interface slip of sand particles adjacent to fibers which was the mesoscopic physical mechanism for the fiber-strengthened effect of fiber-reinforced soil.

关 键 词：土力学 纤维加筋土 界面滑移效应 细观作用机制 抗剪强度准则 

分 类 号：TU441[建筑科学—岩土工程]