Monitoring and analysis of the bending behaviour of discrete piles used to stabilise a railway embankment

Abstract

Discrete piles are used to stabilise infrastructure slopes, especially where there is insufficient additional land to allow construction of large toe berms or regrading of the slope. Compared with more conventional structures such as retaining walls, there are few field data on how discrete piles typically bend and displace under slope loading. This paper presents the results from monitoring a number of discrete piles used to stabilise a railway embankment at Hildenborough, Kent, UK. Bending deflections deduced from strain gauges are compared with the displacements and rotations measured by inclinometer tubes cast into the piles. Four years after pile installation, the piles were bending downslope over their lower halves, with little bending measured in the upper sections. Regrading of the rockfill piling platform shortly after pile construction caused some of the pile loading, with further loading caused by the continued tendency for slope movement. Analysis of the piles using a simple elastic analysis gives bending moments and displacements close to those measured.

Analytical approach to evaluate stability of pile-stabilized slope

“…Based on Figure 12 and supported by other research results [4,22,31,[33][34][35], pile spacing less than five times of the pile diameter is required to generate group effect and the associated soil arching between the piles. For pile spacing greater than five times of the pile diameter, the piles behave almost as single individual piles and the soil can flow around them.…”

Vibration-based monitoring of civil infrastructure: challenges and successes

“…There is also 'routine' instrumentation of selected buildings -and occasionally bridges (Masri et al, 2004)-in local or national strong motion instrumentation programs and there is 'static' instrumentation (e.g. with strain gauges and surveying technology) during infrastructure construction, usually for geotechnical applications (Smethurst and Powrie, 2007).…”

Stabilisation of excavated slopes in strain-softening materials with piles

“…Smethurst & Powrie, 2007;Ellis et al, 2010). A row of spaced piles provides added shear resistance to the movement of the soil by pinning the unstable and stable layers together and by transferring the bending moment caused by the movement of unstable soil to the underlying stable ground (Ellis et al, 2010).…”