Model loading tests on the footing reinforced with prestressed micropiles

摘要

To investigate the mechanism of the bearing capacity of footing reinforced with a group of micropiles, a series of loading tests were carried out on the model footings with and without micropiles. To mobilize the network effect appropriately and improve the bearing capacity, a tensile stress was induced in the micropiles at the beginning of the loading process in this series of model loading tests. As a result, the bearing capacity was improved more than 100% with the prestress of 70% of the pullout resistance, not only in dense and dilative ground, but also in the loose and contractive ground. The network effect of a group of micropiles on the bearing capacity is mobilized positively with the appropriate confinement of the ground material beneath the footing. In this process the micropiles not only provide load bearing capacity directory through their skin friction, but also raise the base pressure on the footing with the confinement.