Micropiles are drilled and grouted piles having diameter between 100 to 250
mm. Due to its small diameter, it is suitable for low headroom and limited
work area conditions. It can be installed without noise nuisance, without vibrations
to surrounding soils and structures and without disruption to the
production operations in industries which makes micropiles suitable for underpinning
and seismic retrofitting of structures. It is necessary to therefore
understand the behaviour of micropiles under different loading conditions.
This work is on vertical and battered micropiles with different length/diameter
ratio (L/D) subjected to vertical and lateral loading conditions. Batter angles
had a significant influence on both the vertical and lateral load carrying capacity.
The ultimate vertical load was found to increase upto a 30° batter. The
ultimate lateral load was found to increase significantly with increasing L/D
ratios upto an L/D ratio of 30 for vertical and 48 for battered piles, beyond
which the increase was found to be not significant. In general, negative battered
micropiles offered more lateral resistance than positive battered micropiles.
The results of the study indicated that the ultimate load capacity and
mode of failure of the micropiles are a function of the angle of batter, direction
of batter and the L/D ratio for vertically and laterally loaded micropiles.
Bruce, D. A. (1995). Small-Diameter Cast-in-Place Elements for Load-Bearing and in Situ Earth Reinforcement. In P. Xanthakos, W. Abramson, & D. A. Bruce (Eds.), Ground Control and Improvement (pp. 406-492). New York: John Wiley and Sons.
Lizzi, F. (1982). The Pali Radice (Root Piles). Symposium on Soil and Rock Improvement Techniques including Geotextiles Reinforced Earth and Modern Piling Methods, Bangkok, 29 November-3 December 1982, D-1-1-D-1-21.
Mitrani, H., & Madabhushi, G. P. S. (2005). Centrifuge Tests Investigating Inclined Grout Micropiles as a Method of Liquefaction Remediation for Existing Buildings. Proceedings of ASCE Geo–Frontiers Conference.
Sadek, M., & Isam, S. (2004). Three Dimensional Finite Element Analysis of the Seismic Behaviour of Inclined Micropiles. Journal of Soil Mechanics and Earthquake Engineering, 24, 473-485. https://doi.org/10.1016/j.soildyn.2004.02.002
Soliman, N., & Munkofh, G. (1988). Foundation on Drilled and Grouted Minipiles. A Case History. Proceedings of the 1st International Geotechnical Seminar on Deep Foundations on Bored and Auger piles, Ghent, 363-369.