A Calculation Model of Grout Migration Height for Post-Grouting Technology

Post-grouting technology has been extensively used in geotechnical engineering to improve the bearing capacity of various piles, which overcomes the technical limitations of the bored piles and recovers the mechanical performance of strata. A considerable amount of earlier research has been conducted to investigate the bearing behavior and reinforcement mechanism of the grouted piles, while very few studies focus on the reinforcement area of post-grouting technique. The theoretical analysis on reinforcement area is of great significance, which is beneficial to correlate the grouting parameters with pile bearing capacity with a target of saving cost and acquiring an optimized design. This paper conducted a theoretical analysis on the grout migration height, and then proposed a new predictive model to estimate the ultimate migration height of cement slurry, where the grout rising process is considered as the flow of Bingham fluid in an axial annular space. A field test was conducted to verify the applicability of the proposed model, and the comparison results revealed that the calculated height is slightly overestimated as compared to the actual values, but it is acceptable in engineering design. The grouting pressure loss and induced permeation was warranted to be studied in future.