Permeation grouting is a ground improvement technique in which low-viscosity grout, such as cement-based or chemical solutions, is injected under controlled pressure into the pores and voids of granular soils without significantly disturbing their structure. The grout permeates the soil matrix and hardens, thereby increasing the strength, stiffness, and impermeability of the treated ground. This method is most effective in coarse sands and gravels where grout can flow freely through the void spa