Experimental Study on the Shear Strength of Fine Sand Reinforced by Grouting and Freezing

In order to investigate the shear strength of fine sand reinforced by grouting and freezing method, a series of direct shear tests was carried out in a temperature-adjusted wall-in refrigerator. Four different soil samples were prepared including non-grouted unfrozen sample (NU), grouted unfrozen sample (GU), non-grouted frozen sample (NF), and grouted frozen sample (GF) considering different factors of moisture content, water–cement ratio, freezing temperature, and curing time. The linear Mohr–Coulomb strength envelope was adopted to describe the relationship between shear strength and vertical pressure of fine sand. The function of freezing and grouting was validated, and the main results show that the shear strength of unfrozen sample decreases with increasing moisture content; in terms of frozen sample, the shear strength increases with moisture content and decreasing freezing temperature; a greater water–cement ratio always produces larger shear strength of GF sample which also increases with curing time as expected; however, the strength of GU sample experiences an opposite trend in water–cement ratio; the effect of different factors on the cohesion c and internal friction angle φ was also discussed and analyzed with many proposed non-linear models.