Study On Crack Propagation Characteristics Of Expansive Soil Based On Image Processing Technology

The dry shrinkage of expansive soil shows volume shrinkage,and the dry shrinkage cracks will be produced in the process of water loss dry shrinkage.The cracks will destroy the integrity of the original soil,provide a channel for water infiltration,reduce the strength and stability of the soil.Therefore,it has a certain engineering practical significance to study the expansion law of the cracks of expansive soil.In this paper,Nanyang expansive soil is taken as the research object,and a series of tests are carried out in order to explore the law of cracks caused by water loss shrinkage of expansive soil.According to the experimental study,the main conclusions are as follows:(1)During the drying process,the expansive soil loses water and cracks appear.The location of the cracks is random.The main cracks appear first,and the secondary cracks appear after the main cracks continue to develop.The cracks expand to a stable number of cracks,and the surface of the soil sample is divided into small areas.(2)The process from the crack appearance to the whole soil sample completely divided into different regions by the crack can be divided into several stages: the crack appearance,the crack rapid expansion,the crack expansion tends to be stable,and the crack development is completed.The greater the thickness of soil sample,the deeper the depth of fracture development,and the greater the distance between each small area divided.The greater the thickness of the soil sample,the longer the time for fracture development to complete.Combined with the image processing of MATLAB,the fracture rate,fracture length,the number of intersections,fracture direction and other indicators are used to describe the fracture propagation law of different thickness.(3)For the first dehumidification,with the decrease of water content,the volume shrinks without cracks.The area of the sample has a linear relationship with the water content.More cracks appear in the soil samples with the increase of times,which cover the whole soil sample surface and are divided into smaller areas.