Crack Development On Compacted Expansive Soil Of Indoor

Expansive soil contents more clay,its mineral composition is mainly composed of smectite and illite,and the soil has significant characteristics of swelling and shrinkage deformation,these two characteristics make the expansive soil swelling-shrinkage, cracks and other fundamental properties.The development and the change of expansive soil crack has an important influence on the steady of slope.Study on expansive soil crack has important practical engineering significance.The law of development in expansive soil crack is helpful to further understanding the mechanism of cracks on the slope stability,so as to provide reference for related engineering treatment and preventive measures.In this paper,motorway of nan yang expansive soil is studied.The compacted expansive soil surface crack developmental processes of indoor in different compaction and water ratio is studied,Making use of digital cameras and photoshop,matlab,image processing technology and the corresponding method.To obtain the various parameters of expansive soil surface cracks,To obtain the various parameters of expansive soil surface cracks,and then the development characteristics of expansive soil surface crack were analyzed and summed up.The main contents are as follows:(1) The method of expansive soils and its preparation process on indoor compaction was improved,the acquisition method of expansive soil surface crack image is optimized. the reinforced soil compaction box was improved,the compaction method is explored,the uniform compaction and the higher compaction degree in large size expansive soil specimens is obtained.While external environmental factors such as lighting conditions is controlled for optimal,the impact of expansive soil’s shade or uneven color in the photographs process by external factors on expansive soil crack is reduced or eliminated.(2) On the basis of the images on expansive soils surface crack,the image processing method of cracks are improved,the crack images are pretreated by Photoshop,including definition the image size,the image of luminance andchrominance is adjusted,and providing convenience for more accurate image analysis on fracture..While after the images are pretreated by Photoshop,the Matlab software can be used to Binary conversion,clear black and white images are acquisited,through further image processing method,relative parameters of compacted expansive soil fissure are obtained.(3)In order to study the two different working conditions on the development and compaction of cracks in expansive soil,its conditions are at the same moisture content, the different degree of compaction and the same degree of compaction,the different degree moisture content.Experiment results show that:at the same water ratio and the different compaction degree,the higher compaction of the degree, the more closely of the soil particles,the fracture rate is larger, and the number of cracks is more, the length is longer,the wide of cracks is more width;at the same compaction degree and the different water ratio, water rate of soil is higher, more water is absorbed by mineral constituents in the soil particles, crack development more completely,the fracture rate is larger, and the number of cracks is more, the length is longer,the wide of cracks is more width.