Model study and 3-D numerical analysis of vertical micropile subjected to oblique pullout loads

Abstract

Details of three-dimensional numerical study on 20 mm gravity grouted and centrally reinforced vertical micropile of 600 mm length in uniform sand bed subjected to pull-out loads of inclinations 0°, 5°, 10°, 15°, 20°, 30°, 45°, 60°, 75° and 90° carried out through ABAQUS are presented in this paper. The results of the model study carried out by the same authors on the same micropile subjected to pull-out loads at the same inclinations were used to calibrate the numerical model as well as to compare the analysis results. Axial and lateral load results of the model study were used to calibrate the numerical model. The calibrated numerical model was used to understand the behaviour of micropile at various inclinations of pull-out load. The results of experimental and numerical studies were compared. A reasonably good agreement was found between the two studies. To simulate the behaviour of soil i.e. sand, Mohr–Coloumb constitutive law was used while linear elastic model was used for modelling of reinforcement bar. Linear elasto-plastic constitutive model was used to define the stress–strain behaviour of grout. Interactions between the grout and sand as well as grout and reinforcement bar were modelled using surface-to-surface contact elements approach based on slave–master concept. The results are shown in terms of load-displacement curves. To gain further insight about the behaviour of micropile, horizontal displacement, bending moment and net lateral soil pressure profiles along the length of micropile were also plotted for different inclinations of pull-out load from the numerical study results.