砂土宏观力学特性与细观结构的相关性试验研究

Experiment Analysis of Relevance of Macro-Mechanics Characteristic and Meso-Structure on Sandy Soil

通过无标点变形量测系统分析桩周土变形场,确定剪切破坏区和显微细观观测点.应用MiVnt系统分析加荷过程中土细观参数变化,细观参数(1+e)/e3、颗粒偏心度与基础位移的相关性最强;随荷载增大,1#,2#点孔隙比下降呈负相关关系,引起剪缩特征,3#点呈正相关关系而剪胀应力松弛;1,2,3#点颗粒定向性均增高呈正相关性,表明颗粒分布有序性减弱,土体具有非稳定性的承载形式.

Through non-marking points digital photogrammetry of deformation measurement system,the biggest shearing strain,volumetric strain and displacement vector distribution of pile the surrounding soil on experiments of half-cut model were analysed to determine the shearing failure area and meso-observation point.The applied MiVnt image analysis system has processed the meso-observation images of soil structure,has sum up and analysed the change of meso-parameters（numbers of particles,total area of particles,voil ratio e,voil ratio increment Δei,major axis mean of particles,minor axis mean of particles,eccentricity mean of particles,particle size,particle direction）,then the decline in soil void ratio of 1# and 2# observation points by the impact of the pile side,soil shear shrink;then increasing 50% in soil void ratio of 3# observation points by soil dilatation,soil structure is significant relaxation.Correlation analysis,soil meso-parameters（1＋e）/e3 was the most relevant on the displacement,particles eccentricity was the most relevant on the displacement,there was a negative correlation between soil meso-void characteristics parameters and displacement in 1 # and 2 # observation points,with the load increasing load and void ratio fell,the soil body appeared shear shrinks characteristic,in point # 3 that was positively correlated,with the increased load soil dilatation and stress relaxation.Soil particle orientations of 1 #,2 #,3 # points are positively correlated,particles orientation of the higher was the orderly distribution of the particles corresponding weakening,the soil was stability of a non-bearing forms.This is an effective method of analysis,through deformation analysis and meso-structure analysis of soil structure on the half-cut model test,studing the macro-and micro-mechanical properties and its correlation.