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Behaviour of Micropiles Groups Subjected to Vertical Loads
Abstract
Micropiles are used to reinforce soils and to support foundations. It may be installed in several directions through existing foundations so as to increase the bearing capacity of the soil and to reduce the settlement. The group effects of micropile groups subjected to vertical loads in granular soils have been investigated by many research workers. However the findings have been found to be inconsistent indicating contradictory group effects. Group behaviour of vertical micropiles groups subjected to vertical loads have been investigated in this study through model testing performed in sand consisting of different relative density. This behaviour is found to be a function of relative density of the sand, slenderness (L/D) ratio, spacing and number of piles in the pile group. The ultimate resistance increases with L/D ratio and with number of piles in the pile group. Ultimate resistance is maximum at 4D spacing in loose sand and medium dense sand at a relative density of 30% and 50%. Ultimate resistance is maximum at 2D spacing and minimum at 6D spacing in dense sand at a relative density of 80%. Efficiency of micropile groups is found to be a function of L/D ratio, density of the sand, the number of piles and spacing of the pile group. Correlations have been developed between the ultimate load and the various parameters involved.
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