Rotational and Penetration Rate Effects on the Formation and Axial Capacity of Pressure-Grouted Helical Piles

The Pressure Grouted Helical Pile (PGHP) is an innovative composite foundation system built in one step by combining the structural stiffness of a helical shaft and the deformability of a cement treated pile body. This system of - high installation efficiency, high structural integrity and improved pile - soil interface bonding - has demonstrated wide-spread application potential in geotechnical engineering. In order to systematically investigate its formation process and load-bearing behavior, 6 groups with 24 model piles were tested under simulated marine soft clay conditions. The research examined the effects of the major construction variables, such as rotational velocity and penetration rate on pile diameter, axial load-bearing capacity and mechanics of the cement stabilized soil. The increases in rotation speed between moderates and excessive increases increase the uniformity of the soil-cement and pile integrity, while excessively high speeds decrease the grout intake, resulting in smaller pile diameters and weaker strength. This study explains the mechanisms by which the construction parameters control the formation and performance of PGHPs, which not only shed light on the formation of PGHPs but also offer practical information for the design optimization and engineering application of PGHPs.