Microstructure Parameters Measurement For Granular Soil Model Using Digital Image Technology

In geotechnical engineering, it's meaningful to measure the microstructure parameters of granular soils in model test for which can be used to investigate deeply the nature of granular soils' mechanical behavior. Nowadays the studies on this topic are mainly based on Oda's method, that is, firstly dissection the specimen, and then shot the micro image of the section from which the microstructure parameters can be computed by use of digital image processing techniques. However, this method is really complicated, and also it can't get the parameters during the process of the test.Based on digital image processing and analysis technology, this paper aims to proposing a method to compute the microstructure parameter of granular soils from the photo which is shot from the surface of the model box in granular soil model test. Firstly, some requisition is proposed for the operation in test to make sure that granule and hole can be differentiated approximately by a threshold to magnitude of the image. Then by use of morphologic watershed segmentation, along with image pretreatment steps such as smoothing, region marking and region merging, the edge image is acquired. The coordinates of granular edge and other necessary data can be gained by scanning this image. Based on those data, a basic structure is proposed, from which the parameters about the area and shape of granules, the parameters about the area and shape of holes, and the parameters about the contact relation of two granules can all be computed. In the course of studying, we also have developed the software called GeoDIP, which can be used to put the method proposed here into practice. So next this paper gives a brief introduction to the process of developing the software and the way of using it. Finally a simple example is showed with the software GeoDIP.