Abstract: In order to study the features of shear strength of soils stabilized by cement mortar, to provide a theoretical reference to rationally determine the engineering application ratio of soils stabilized by cement mortar, some CU triaxial tests are performed on the soils stabilized by cement mortar, based on the four aspects: sand content, cement mixing ratio, water content of raw soil and sand diameter. It is shown that the mixed sand can improve the strength of stabilized soils, in general, the effective cohesion increased and then decreased with the amount of mixed sand increased, the turning point of the doped amount of sand is the best amount of mixed sand (about 10%), while effective friction angle increasing continuously. The cement mixing ratio increasing can effectively improve the strength of stabilized soils under a certain amount of mixed sand; as the water content increasing, cohesion of stabilized soil appears as linear decrease relationship approximately; while the internal friction angle remains almost unchanged; and when using cement mortar in the treatment of high water content of soft ground, the appropriately increasing the volume of mixed sand can more sharply improve the mechanical properties of stabilized soil. When the admixture ratio fixed, sand diameter can influence the shear strength of stabilized soil to some extent. In general, the shear strength of stabilized soil is higher when it using the sole sand diameter; and uniformity coefficient Cu tends to the largest, coefficient of curvature Cc tends to the minimum with the sole particle size and good gradation of stabilized soils

Key words: composite foundation, cement-soil, CU triaxial test, sand content, cement content, sand diameter