Interpretative analysis of lateral load-carrying behavior and design model for inclined single and group micropiles

In this study, the lateral load-carrying capacity of micropiles was investigated focusing on the effect of micropile inclination. A series of model load tests was conducted for both single (SMP) and group (GMP) micropiles with various configuration conditions of inclination angle, load direction, and micropile spacing. To clarify the load-carrying mechanism of inclined micropiles, a finite-element (FE) analysis was performed. The lateral load-carrying capacity of inclined SMPs increased with θ up to 30° for δ = 0°, whereas opposite trends were observed for δ = 180°. The lateral load-carrying capacity of inclined GMPs increased continuously with θ owing to the fixity effect with micropile cap. From the results of FE analyses it was found that the main resisting components of inclined micropiles for the lateral load- carrying capacity are the passive failure zone and skin friction mobilized along the micropile surface. Design methods for single and group micropiles subjected to lateral loads were proposed. The values of regression coefficients were evaluated using the results from the model tests and FE analyses. To check the validity of the proposed methods, full-scale field load tests were conducted and used to compare measured and estimated load capacities. Estimated results obtained using the proposed method were in good agreement with measured results.