Polymer has broad application prospects in soil stabilization. However, there is currently little research on the strength and deformation characteristics of polymer treated soil, as well as the degree of influence of different influencing factors. In this work, a series of unconfined compression strength and shear strength tests were performed on a water-soluble polymer treated sand, and subsequently, the effects of polymer content, curing time and dry density on the strength and deformation characteristics of the treated sand were analyzed. Also, the degree of influence of the three research variables was elucidated using correlation analysis. And finally, the related mechanism of treated sand was revealed using electron microscopy scanning (SEM) observations. The results show that, (1) The three studied variables significantly enhance the unconfined compression strength and shear strength, and the influence of polymer content and curing time on shear strength was mainly reflected in the cohesion. The strength of polymer treated sand is significantly and positively correlated with curing time, and moderately and positively correlated with polymer content and dry density. In addition, these relationships can be represented by a logarithmic function or linear function. (2) As the polymer content, curing time and dry density increase, the shear characteristics of treated sand change from shear hardening type to shear softening type, and the shear failure displacement of treated sand decreases gradually (as dry densities decreases). Also, its axial stress-strain curve shows obvious post-peak easing phenomenon and then produces obvious changes, and the compression failure pattern is dominated by bulging and accompanied by cracks, what’s more, this pattern gradually changes from E-type to G-type (as dry densities decreases). (3) The deformation capacity of treated sand is strongly and positively correlated with curing time, moderately and positively correlated with dry density, while the correlation with polymer content is not significant. Additionally, the peak strain has a polynomial (or linear) relationship with three studied variables. (4) For this polymer treated sand, the optimum mixing content is about 2%, and when the curing time reaches 24h and above, it shows a better treatment effect. (5) The polymer forms an effective and stable three-dimensional membrane structure in the sand particles by adsorption, bonding and filling effects, and thus effectively improves the microstructure of sand. The proportion of changes in the types of polymers under load determines the strength, deformation capacity, and failure mode of treated sand, which is closely related to polymer content, curing time and dry density.
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