摘要
为探究粉砂-结构物剪切过程中接触面受力变形特性及剪切带形成特征,采用自行设计的半模直剪仪进行不同法向应力、结构物粗糙度及含水率条件下的粉砂-结构物单调剪切试验,并通过数字照相变形量测技术(DPDM),分析剪切带内位移场与应变场规律。再结合PFC2D揭示剪切过程中细观颗粒运移与孔隙变化规律对剪切带形成特征的影响。结果表明:(1)粉砂-结构物剪切过程中粉砂剪应力-剪切位移曲线分为线性增长、缓慢增长、趋于稳定三个阶段,峰值剪应力随法向应力、结构物粗糙度增大而增大,随砂样含水率增大而减小;(2)通过分析砂样位移场与应变场,发现在接触面上方砂样内形成一条中间宽两端窄的剪切带;(3)PFC2D模拟粉砂-结构物单调剪切试验表明,剪切带形成特征受接触面颗粒运移影响,剪切带内距离接触面较近的颗粒位移与速度变化大,距离接触面较远的颗粒位移与速度变化小,砂样不同部位处颗粒运移位移与速度变化不同是导致剪切带中间宽两端窄的根本原因;(4)粉砂-结构物单调剪切过程中砂样空间内孔隙率不同,其中与接触面距离较近且位于中部的砂样孔隙最小,这印证了剪切带的形成特征。
In order to explore the stress and deformation characteristics of the contact surface and the formation characteristics of shear bands during the shear process of silt-structure,a self-designed semi-mold direct shear apparatus was used to carry out the monotonic shear test of silt-structure under different normal stresses,structure roughness and water contents.The displacement field and strain field in the shear band were analyzed by the digital photographic deformation measurement technology(DPDM).Finally,PFC2D was used to reveal the influence of meso-particle migration and pore variation on the formation characteristics of shear bands during the shear process.The results showed that,during the shear process of silt-structure,the shear stress-shear displacement curve of silt was divided into three stages,i.e.,linear growth,slow growth,and stabilization.The peak shear stress increased with the normal stress and structure roughness increasing,and decreased with the increase of the water content of the sand sample.By analyzing the displacement field and strain field of the sand sample,it was found that a shear band with wide middle and narrow ends was formed in the sand sample above the contact surface.PFC2D simulated monotonic shear test of silt-structures showed that the formation characteristics of the shear band were affected by the particle migration of contact surface.The displacement and velocity of particles close to the contact surface in the shear band change were large,while the displacement and velocity of particles far from the contact surface were small.The difference of particle migration displacement and velocity at different parts of sand sample was the fundamental reason for the narrow width of the middle and both ends of the shear band.During the monotonic shear process of silt-structure,the porosity in the sand sample space was different,and the sand sample with a close distance to the contact surface and located in the middle had the smallest porosity,which confirmed the formation characteristics of the shear band.
作者
闫晓妍
杜强
刘超凡
YAN Xiaoyan;DU Qiang;LIU Chaofan(School of Civil Engineering,Inner Mongolia University of Technology,Hohhot 010051,China;Key Lab.of University of Geological Hazards and Geotechnical Engineering Defense in Sandy and Drought Regions,Hohhot 010051,China;Inner Mongolia Engineering Research Center of Geological Technology and Geotechnical Engineering,Inner Mongolia University of Technology,Hohhot 010051,China)
出处
《内蒙古农业大学学报（自然科学版）》
CAS
北大核心
2024年第3期60-67,共8页
Journal of Inner Mongolia Agricultural University(Natural Science Edition)
基金
内蒙古自然科学基金项目(2022LHMS0501)
内蒙古工业大学科学研究项目(BS202044)
内蒙古自治区直属高校基本科研业务费项目(JY20220096)。
关键词
粉砂
剪切带
位移场
应变场
数值模拟
宏细观
Silt
Shear band
Displacement field
Strain field
Numerical simulation
Macro and micro vie
