剪切试验中筋土界面土颗粒运动的细观量测

Micromeasurement of Soil Particle Movement in Geogridsoil Interface Direct Shear Test

摘要:

基于互相关理论,将粒子图像测速(PIV)技术应用到筋土界面直剪试验中,从细观角度来研究试验过程中土颗粒的运动情况.筋土界面的剪切试验分别在法向应力为50和87.5 kPa下进行.通过对一系列试验结果的分析,可以得到:界面附近砂颗粒的水平位移和竖向位移均随着剪切位移的增加而增加,但增加的速率随剪切位移逐渐减小;试验中砂颗粒的水平变位较为明显,但随着距离筋土界面高度的增加,变位的程度有所减弱;试验中界面附近发生变位的砂颗粒范围不超过45 mm,即剪切带的范围大致为45 mm,相当于试验用砂平均粒径的7～9倍.

Abstract:

Based on crosscorrelation theory,the particle image velocimetry (PIV) technology is applied to reinforcementsoil interface direct shear test,and the soil particle movement near interface during the direct shear test is measured and analyzed from the standpoint of microscopic view.Reinforcementsoil interface direct shear tests were performed under 50 and 87.5 kPa normal stress,respectively.By analyzing the results of a series of tests,several conclusions can be obtained:horizontal and vertical displacement of soil particles increase with shear displacement increasing,but the increasing rate decreases with shear displacement; in the direct shear tests the horizontal displacement is more evident than vertical movement and it attenuates with the distance to geogridsoil interface; the scope of soil particle displacement doesn’t exceed 45 mm,namely,the thickness of shear band is approximately 45 mm,which is 7～9 times of the average grain size of soil particle used in the direct shrear tests.