不同细颗粒含量土体管涌三轴试验研究

Research on Piping and Triaxial Test in Soils with Different Fine Particle Content

为探究不同细颗粒含量土体管涌机理以及管涌后土体力学性质,选取三种不同细颗粒含量的土体,利用自行研制的管涌三轴仪,选择向上管涌的方法模拟管涌实际情况。通过管涌试验以及管涌后的排水剪切试验,分析了细颗粒含量对临界水力梯度、累计涌砂量、峰值强度以及体变的影响。结果表明:管涌发生前,临界水力梯度和临界流速随细颗粒含量的增加而增加;土体在较高的同一水力梯度作用下,累计涌砂量增长速度随时间逐渐减小,流失相同的细颗粒含量,累计涌砂的时间随细颗粒含量的增加而减小;随着细颗粒含量的增大,管涌后土体峰值强度呈不规则变化,土体体积先发生剪缩后发生剪胀,试样体积最大剪缩量随细颗粒含量的增大而增大。

In order to explore the piping mechanism and the mechanical properties after piping of soils with different fine particle content,three kinds of soils with different fine particle content were selected and piping up was simulated by self-developed piping triaxial apparatus. Through piping test and drainage shear test after piping,the effects of fine particle content on critical hydraulic gradient,cumulative sand inflow,peak strength and volume change were analyzed. The results show that the critical hydraulic gradient and critical flow velocity increase with the increase of fine particle content before piping. The growth rate of cumulative sand inflow decreases with time under the action of higher hydraulic gradient.The cumulative time of sand gushing decreases with the increase of fine particle content when the same fine particle content is lost. With the increase of fine particle content,the peak strength of soil changes irregularly after piping,the volume of soil first shears and then dilates,and the maximum volume shrinkage of sample increases with the increase of fine particle content.