Experimental study on the pile-tip resistance bearing characteristics of postgrouting at pile tip

Abstract

Postgrouting at the pile tip enhances the performance of cast-in-place piles. To clarify the performance of tip and side resistances, this study analyzed static load test data from two test piles before and after grouting. Mechanisms underlying an improvement in tip resistance and the influence of postgrouting on side resistance were investigated via theoretical analysis. Finally, a design method for tip resistance control via settlement was proposed. Results indicate that the ultimate bearing capacity of piles increases after grouting compared to before, underscoring the importance of tip grouting in gravelly soils and its profound impact on load transmission in pile foundations. Postgrouting at the pile tip enhances the strength as well as initial stiffness of the bearing stratum, ultimately elevating the overall pile foundation-bearing capacity. Additionally, tip grouting helps in strengthening overall side resistance, especially around the pile tip. The grouting procedure has an impact on the soil’s arching effect at the pile tip; the extent of the arching effect and an increase in horizontal tension close to the pile tip are positively correlated with the effectiveness of grouting reinforcement. The design method for tip resistance control via settlement based on measured data statistics was validated using engineering examples, and the method has a practical reference value.

Keywords

postgrouting at pile tip / pile-tip resistance / pile-side resistance / negative skin friction / enhancement effect / precompression effect

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Funding

National Natural Science Foundation of China(52008100)

National Natural Science Foundation of China(52178317)

Natural Science Foundation of Jiangsu Province(BK20200400)

China Postdoctoral Science Foundation(2022M723534)

Natural Science Foundation of Jiangsu Higher Education Institutions of China(23KJA560005)