In-situ test study on uplift bearing capacity of micro-piles in transmission lines

Abstract

In order to expand the application of the micro-pile foundation in transmission lines and reveal the uplift bearing capacity of micro-piles in mountain rock foundation. In-situ uplift load tests of micro-piles with different pile diameters and pile lengths were carried out. The load-displacement curve of micro-piles under load test and its ultimate anti-lifting bearing capacity were obtained. The uplift bearing characteristics of the single pile and group piles of micro-pile foundation in mountain rock foundation, and the variation of axial force and lateral resistance of piles were analyzed. The results show that the uplift bearing capacity of micro-piles is affected by the rock-socketed depth, and the bearing capacity is controlled by the strength of pile material when the rock-socketed depth exceeds a certain value. The variation of the pile diameter will affect the axial force of micro-piles and the distribution of pile side resistance. To give full play to the uplift bearing capacity of micro-piles, the reasonable pile diameter and pile length are needed. Each pile in the pile group foundation fails to give full play to its uplift bearing capacity. The uplift bearing capacity of the pile group is controlled by the tensile bearing capacity of the column.