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Use Image-Pro Plus software, high-precision inductive sensor TR200, electro n microscope and ENVI image processing system to quantitatively study aggregate mo rphology from three scales: macro, meso, and micro, and obtain P, As, R, Ry, Rsm, et c. 17 quantitative indicators of morphological characteristics, compared with the occup ancy rate of the aggregate broken surface and the roughness of the aggregate surface. T he results show that the 17 morphological characteristics indexes are feasible for multi -scale quantification of aggregate morphology. Macro-morphological characteristics di rectly indicate the angularity and needle-like shape of materials, micro-morphological characteristics directly indicate the roughness of materials surface, and micro-morphol ogical characteristics directly indicate the micro-morphological characteristics of mate rials. The quantitative indexes of aggregate morphology at micro-scale and micro-scal e are improved, and the results are helpful to reveal the morphological characteristics o f aggregate comprehensively.

* Geogrids is widely used because of its effective interlocking with the surrounding soil, the improvement to the mechanic properties of soil and the low costs. At present, indoors experiments of interface features are conducted to study the reinforcement mechanism of geogrids, including the tests of direct shear and pullout. Due to the limitation of facility sizes and other experimental conditions, most current experiments do not completely consider the actual mechanic situation of geogrids in practical engineering. So new methods should be worked out. Based on numerical methods, the paper respectively studies the features of direct shear friction and pullout friction of geogrids to analyze the influences of vertical distances between geogrids and the thickness of salient points on the interface features. The research shows that the strength indexes of interface are relatively larger and the functions of reinforcement are stronger when the vertical distances between geogrids are smaller and the thickness of salient points are larger. The results of the study indicate that to identify the reasonable strength indexes of geogrids interface based on numerical methods is feasible. INTRODUCTIONS

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