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钙质砂是一种以碳酸钙为主要成分的特殊砂土,由于在形成过程中保留了原生物的骨架,故钙质砂颗粒不仅形状各异而且富含孔隙。颗粒孔隙的存在对钙质砂的压缩、剪切、强度和破碎性等力学性质有很大影响。针对这一问题,取南海一处岛礁建设地基的钙质砂试样,根据粒径大小将其分为6个不同的粒组,在每个粒组中选出不同形状的代表性颗粒,对其进行电镜扫描试验。借助MATLAB图像处理程序,选取合适的阈值对扫描试验得到的图片进行二值化处理,对钙质砂的连通孔隙进行了分析,系统的研究了不同粒径和粒形钙质砂颗粒的表观孔隙率的分布规律。结果表明:对于粒径小于1 mm的颗粒,面孔隙度随着粒径的增大而增大,不同形状颗粒面孔隙度差别不大;粒径超过1 mm后,面孔隙度随着粒径的增大而减小;条状颗粒面孔隙度最大而片状颗粒的面孔隙度最小。
Calcareous sand is a kind of special sand with calcium carbonate as the main component. Due to the original skeleton remains in the process of formation, the calcareous sand particles not only have different shapes but also are rich in pores. The existence of particle pores has a great influence on the mechanical properties such as compression, shear, strength and crushing of calcareous sand. In response to this problem, we take a sample of calcareous sand from the foundation of an island reef in the South China Sea and divide it into 6 different grain groups according to the grain size. Representative grains of different shapes are selected in each grain group, Electron microscopy of the test. With MATLAB image processing program, select the appropriate threshold to scan the images obtained by the binarization processing of calcareous sand connectivity pores were analyzed, the system of different sizes and granulated calcareous sand particle appearance The distribution of porosity. The results show that for the particles with a diameter of less than 1 mm, the surface porosity increases with the increase of the particle size, and the difference of the surface porosity of the particles with different shapes is not significant. When the particle size exceeds 1 mm, Of the particles decreases with the increasing of the particle size.