中文摘要：

在控制吸力的非饱和土三轴试验中对试样进行变形测量,常规方法都存在一些难以克服的技术缺陷。数字图像测量技术的引入,为避免常规测量方法的技术缺陷对试验结果的影响提供了一种新的解决方案。同时,能够更加准确地测量受端部约束影响较小的试样中部1/3区域的局部轴向变形、径向变形和估算体积变形。在控制吸力条件下进行了非饱和压实土的三轴压缩试验,运用数字图像测量方法测量试样整体与中部1/3区域的变形,将两组试验数据进行比较分析,结果表明：端部约束对非饱和土试样变形有明显的影响,试样中部1/3区域的变形性质与试样整体存在明显差异,其试验结果更能反映非饱和土试样的基本变形性质。

英文摘要：

A new means of strain measurement of unsaturated soil specimen is introduced in suction-controlled triaxial tests based on digital image measurement method.The digital image measurement method can non-contactually and selectively measure the deformation of whole and local specimen and overcomes some critical shortcomings of using conventional strain measurement method for unsaturated soil specimen in suction-controlled triaxial tests.Meanwhile,the deformation process of the unsaturated soil specimen can also be recorded and analyzed after tests finished.The local deformation of middle section of unsaturated soil specimen that is relatively little influenced by end restraint can be handily and accurately measured by adopting the method.The deformation measurement results of unsaturated compacted soil specimens show that the end restraint has material effect on deformation of specimens and deformation characteristics of middle section is evidently different from the whole specimen that is influenced by end restraint in suction-controlled isotropic loading and triaxial compression tests.So the deformation measurement results of middle section can correspondingly really reflect basic deformation characteristics of unsaturated soil.