A hollow pile extended with a micropile: tests and modelling

Abstract

The development of a precast hollow pile extended with a micropile is described. A hole at the pile centre allows the subsequent installation of a micropile through its interior, extended under the pile toe. Once the pile has been driven to refusal in hard soils or rock, an increase in its bearing capacity under compression or tension, as well as a decrease in the lateral displacement under lateral loads is permitted. Cyclic axial loading tests with a rigid frame holding four tension piles surrounding a central compression pile were performed in addition to horizontal loading tests. The piles were instrumented with inner extensometers. A hardening soil was used as a material model. The piles were modelled with finite elements of both embedded and volume piles. Both types of model pile can be simulated in tension and lateral loading tests but only the volume pile can be used in compression tests due to the step existing at the joint between both types of pile. Good agreement between measured and calculated displacements was obtained and the load distributions calculated and measured with extensometers were similar.

La modelización de los pilotes en el método de elementos finitos (EF)

“…La secuencia de carga de tracción fue similar, pero reduciendo las cargas a ¼. Los detalles de los ensayos y los resultados preliminares han sido descritos por Justo et al (2016). Sin embargo, los resultados se han mejorado aquí utilizando una mejor malla.…”

Editorial

“…This suggests the mix-inplace MIDOS piling technique could be suitable in carbonate sands. Justo et al (2016) report the results of field load tests with optical fibre strain gauges and 3D finite-element modelling of 400 mm square hollow precast concrete piles extended by 145 mm dia. drilled micropiles.…”