基于图像相关分析的土体剪切带识别方法

提出了一种基于数字照相量测和图像相关性分析技术的土体剪切带识别方法。首先，在模型试验中，用数码相机采集土体全程变形图像序列；接着，在图像全局观测范围内粗略搜索到剪切带发生的大致区域；然后，布置跨越剪切区域的多对测点线，进行局部范围精密搜索，识别出剪切带的准确位置与形状, 并确定剪切带的边界点。与在模型上描画网格线等传统方法相比，该法操作简单，量测准确，适用于模型试验中岩土材料的剪切带识别及其厚度、倾角、带内变形和演变过程等特性的试验研究；最后，给出了一个大型砂土剪切试验中的应用实例。结果表明，基于图像相关分析的识别土体剪切带的方法是可行而有效的。

A technique of identifying shear band accurately in granular soil using image correlation analysis

An effective technique of measuring the shear bands is put forward using digital photogrammetry and image correlation analysis.At first,a series of specimen images were collected by digital camera with high resolution.Subsequently,the approximate region of shear band was identified firstly in the full observed scope on the image by coarse image correlation analysis for saving time.And then refined analysis in the local observed scope,where the shear band occurred,was conducted by specifying pairs of alinement points on image with one pixel interval covering the shear band.Finally,when shear band was recognized,its edge points were marked manually for the subsequent quantity analysis of the thickness and direction of shear band together with the deformation inside.This technique is more accurate than the widely adopted method of painting mesh on soil specimen.Its application is illustrated by a large-scale direct shear test of granular soil.