Experimental Investigation of Grouted Helical Piers for Use in Foundation Rehabilitation

Abstract

Building rehabilitation is critical for numerous older urban areas, many of which have inadequate foundations to support new demands. Consequently, development of practical methods to strengthen existing foundations is crucial. In engineering practice, both subsurface grouting and helical piers have been widely used to address these issues by strengthening the foundation. If the solid shaft of a typical helical pier is replaced by a hollow shaft, then helical piers provide the ability to deliver grout. It is hypothesized that these grouted helical pier systems (GHPS) could address foundation strengthening needs. This paper presents findings from an exploratory research program where grouting and pier placement tools were developed and tested on the large geotechnical centrifuge at the University of California, Davis. Experimental methods and procedures developed are presented, and observations regarding the formation of grout bulbs under different conditions are analyzed. Physical observation of the test specimens indicates that average grout bulb diameters of 0.6-1.9 times the helix diameter (D h ) are attainable. For similar grout mixes, 20-50% larger grout bulbs can be attained by adding just a modest amount of injection pressure. Future research may use these results to develop load performance data.

Behaviour of helical anchors subjected to cyclic loadings

“…Centrifuge modelling allows for parametric studies with relatively small effort and lowcost compared to full-scale tests. For this reason, this modelling technique has been used successfully to investigate the performance of plate anchors , and helical anchors Tsuha et al, 2007;Bian et al, 2008;Wang et al, 2013). However, the occurrence of scale effects can influence the results of model experiments of geotechnical problems in granular soils.…”

Análise do comportamento de fundações por estacas helicoidais com injeção de calda de cimento

“…Todos eles são experimentais e em sua maior parte os resultados são obtidos por meio de modelagem física. Nos trabalhos de laboratório foram ensaiados modelos reduzidos de estacas metálicas helicoidais instaladas em areia testados a 1g e acelerados em centrifuga (MANKE, 2004;BIAN, 2006;LAEFER et al, 2007;BIAN et al, 2008;KHAZAEI e ESLAMI, 2016). Os ensaios em verdadeira grandeza (SANCHEZ, 2014 e NABIZADEH e CHOOBBASTI, 2016; 2017) foram realizados em solos arenosos, silto-arenosos e argilosos.…”

Avaliação de soluções alternativas para o aumento de capacidade de carga de fundações por estacas helicoidais

“…EmBian et al (2008), comentam-se que uma maneira econômica e eficiente para melhorar a capacidade de carga e rigidez de uma fundação existente seria combinar uma estaca metálica helicoidal com argamassa injetada Bian (2006). realizou injeções com argamassa em estacas modelos com diferentes configurações de hélice em centrífuga.…”