基于数字图像的砂土压缩变形模式的试验研究

基于数字图像处理技术，利用图像分析程序包PhotoInfor分析了侧限压缩条件下砂土各加荷阶段土体位移的产生、发展与演化全过程，发现砂土的位移场类似于抛物线形状，位移等值线呈轴对称分布，位移量最大的区域总是发生在上透水石的下底面中心处。单调加荷条件下，位移增量主要集中在局部变形带附近，其范围有继续延展和贯通的趋势，顶部、中部测点的土体位移与整体压缩量基本呈同步增长；顶部的土体位移量始终大于中部，加荷的中后期差别更加明显。与粉质黏土位移场进行对比试验分析，砂土内部的应力传递、变形模式以及荷载的影响范围均表现出明显的差异。上述研究为深入探讨基底压力的分布规律，利用宏观试验现象研究砂土细观结构变化的定量模型提供了新的思路。

Experimental study of compression deformation patterns in sands based on digital image analysis

By using the image analysis software package PhotoInfor,which is based on the digital photogrammetry for deformation measurement technology,we analyze the generation,development and evolution process of displacement in sands during each load level of confined compression tests.The results can show that,the axisymmetric displacement fields of sands are similar like parabola,displacement’s equivalence lines are axisymmetric-distributed,and the largest increment of displacement always occurs at the bottom’s center of the up porous stone.With the monotonic loading,displacement increment mainly concentrates in the vicinity of localized deformation zones,with an obvious trend of continuous extention and transfixion.The displacement at the top and the middle position keeps linearly increasing with the overall compression deformation.However,the displacement of the testing point at the top is always larger than the middle one.Such phenomenon will be more obvious during the metaphase and the anaphase of the tests.Compared with the displacement fields of silty clay sample,the granular soil will represent a conspicuously different rule for the stress transferring route,deformation patterns and loading impact scope.The research can put forward a new concept to study the stress distribution rules under foundations,as well as to study the quantitative model of sands’ microstructure by macro experimental phenomenon.