PARTICLE SHAPE CHARACTERISTICS OF CORAL SANDS

The microscopic characteristics such as the shape and roughness of coral sand can affect the macro-mechanical properties of sand. Image processing technology is used to analyze the aspect ratio,area,roundness and fractal dimension of coral sand. 3D measuring microscope technology is used to measure and calculate the surface roughness of the sand grains,the interface expansion area ratio,and the arithmetic mean curvature of the peak apex. The test results show that the aspect ratio of most coral sand particles is between 1.2~1.5,and the aspect ratio presents a negative skew distribution. The roundness of sand particles is mainly concentrated in the range of 0.75~0.9,which shows a negative skew distribution. The area of sand particles is mainly between 0.015~0.035 cm²,and the area of the particles has a positive skew distribution. The fractal dimension D of sand particles is basically between 1.04~1.10,indicating that sand particles have strong self-similarity. The roughness analysis results show that the coral sand particles have poor surface flatness,with many erosion pits distributed,and sharp bulges locally. The sand surface roughness S_a is 20.078 μm. The interface expansion ratio S_dr is 0.167,and there are several inclined surfaces distributed on the surface of the sand particles. The arithmetic mean curvature S_pc of the peak apex is 216.641 mm^-1,which shows that the contact between sand particles is sharp. The above research results can provide references for the study of the macro and micro mechanical properties of coral sand.