Abstract: The finesilty sand is widely distributed in the Yinchuan Plain with shallow deposit and large thickness. It is the main bearing layer for buildings with shallow spread footings. However, few mechanical properties test data available for the engineering projects reference. Therefore, considering dry density and saturation, the orthogonal test scheme wasplanned, and the strength characteristics of finesilty sand in Yinchuan Plain wasevaluated by laboratory undrained direct shear tests usingthe straincontrolled electrical direct shear instrument. Factors that might affect the strength properties and their significance of the fine silty sand were explored throughout the regression correlation analysis model. The following results can be summarized: The shear strength of Yingchuanfine silty sand nonlinearly increaseswith the increase of the dry unit weight and higher unit weight yields with higher shear strength. From the significance descent ranking are the dry density and the degree of saturation. In soil improvement projects using dynamic compaction, conventional rolling compaction and the displacement column methods, the dry unit weight can be used as the index parameter. For cohesion and friction angle soils, the impact of dry unit weight and the degree of saturation on the cohesion are higher than on the internal friction angle. It is also concluded that the regression model on the Yingchuan fine silty sand soils are successful.

Key words: Fine Silty Sand, Strength Parameters, Regression Model, Yinchuan Plain