Load-Displacement Relationship of Single Piles in Clay Considering Different Tip Grouting Volumes and Grouting Returned Heights

A total of five model nondisplacement piles tests were conducted to analyze the different volumes of tip grouting on the pile load-displacement response. The ultimate compressive bearing capacity of single piles with different tip grouting volumes is higher than that of the nongrouting test pile by 37.5%-112.5%. In addition, the height of the grouting returned is approximately 14 times the pile diameter (approximately 0.65 m) above the pile tip. A simple analytical method is presented for nonlinear analysis of the load-displacement response of a single postgrouting pile, considering different tip grouting volumes and grouting returned heights. Two models are adopted in the proposed approach. One model uses a modified hyperbolic model, which introduces the enhancement coefficients alpha(s) and beta(s) to describe the contribution of the grouting returned on the pile shaft resistance-displacement relationship. The other model is based on test results that capture the pile tip resistance-displacement response at the pile tip. In addition, a highly effective algorithm is proposed for the analysis of the load-displacement behavior of a single postgrouting pile based on the two models. Comparisons are made among the results of the present method, model test measurements, another analytical method, and two field cases study measurements. The comparisons show that the results of the present method are in good agreement with the measured results of the model tests, the measured results of two field case studies, and the calculated results derived from the other analytical method. A parametric study was conducted to analyze the influence of grouting volume on the pile shaft resistance enhancement coefficient and parameters related to the proposed model on the load-displacement response. (C) 2019 American Society of Civil Engineers.