For bored cast-in-place piles, shaft grouting is dominated by compaction and fracturing, while base grouting is dominated by permeation and compaction. Splitting grouting refers to the process in which high-pressure grout overcomes the initial compressive stress on the principal stress plane of the soil, causing the soil to fracture; the grout then penetrates along the fractures to fill voids and compacts the surrounding soil, promoting consolidation and thereby improving the strength of the grouted zone. If the grouting zone is at the pile base, the grout first fractures and permeates the sediment zone at the base, densifying the sediment and the soil near the pile tip, producing a "bulb" effect that increases end bearing capacity. If the grouting zone is at a certain section of the pile shaft, a "diameter expansion" effect similarly occurs at that section. Extensive pile test data show that base grouting not only increases the pile's end bearing capacity but also significantly improves shaft friction within 5 m or even a larger range above the pile tip. If grouting is applied at a certain cross-section of the shaft, the shaft friction within a certain range above that section is likewise markedly improved.

　　The pile tip and the pile perimeter are open spaces for the grout. Because they are below the ground surface and constitute concealed works, current monitoring methods are limited, and achieving the desired grouting effect must rely on good construction technology.