<p>Building infrastructure on soft soil presents significant difficulties due to the soil’s high compressibility, low load-bearing capacity, and tendency for lateral deformation.Granular column techniques may decrease settlement in weak and soft soils by improving bearing capacity and accelerating the dissipation of excess pore water pressure. Based on the unconfined compression test results, it was observed that the undrained shear strength improved as the height-penetrating ratio increased; however, once it reached 80%, it began to decrease. The undrained shear strength exhibited the highest improvement at an area replacement ratio of 10.24% when it reached a value of five times the diameter of the column. According to the Mohr-Coulomb failure criteria, the compressibility and shear strength of soft clay reinforced with polypropylene columns were greatly affected by the effective confining pressure. Clay reinforced with polypropylene columns could not perform effectively under high confining pressure. Polypropylene columns were squeezed by high effective confining pressures. Polypropylene was squeezed because it was brittle and was unable to resist effective confining. As a result, the polypropylene particles were crushed, and crushed particles filled the voids between them. Furthermore, smearing conditions between polypropylene and clay formed. In general, it can be concluded that the installation of polypropylene columns can improve the shear strength and compressibility of the soft clay.</p>