<p>Microbial-induced calcite precipitation (MICP) is considered a promising biotechnology for treating sandy soils, offering advantages such as being green, low-carbon, and environmentally friendly. In this study, a series of biogrouting tests were conducted using cylindrical models (0.3 m in diameter and 0.5 m in height) to examine the effects of the injection method (two-phase method and low-pH one-phase method) and the addition of skim milk powder on biotreatment efficiency and uniformity. A total of 128 cuboid samples from different locations were extracted to measure calcium carbonate (CaCO₃) content, shear wave velocity (SWV), and unconfined compressive strength (UCS). The experimental results showed that sand columns treated with the two-phase method exhibited higher CaCO₃ content, SWV, and UCS compared to those treated with the low-pH one-phase method under the same treatment cycles. Additionally, while the inclusion of skim milk powder promoted CaCO₃ precipitation, it negatively affected the uniformity of its distribution. Further measurements of CaCO₃ content at 320 points revealed that the main precipitation zone of CaCO₃ shifted from the injection well to the extraction well with increasing depth, influenced by hydraulic action and flow patterns. Overall, this study lays a foundation for optimizing MICP treatment strategies and provides benchmarks for large-scale applications.</p>