Instrumented pile tests are vital to establish the performance of a pile and validate the assumptions made during initial design. Conventional instrumentation includes vibrating wire strain gauges and extensometers to measure the change in strain or displacements within a pile. Although these strain and displacement gauges are very accurate, they only provide strain/displacement readings at discrete locations at which they are installed. It is therefore common to interpolate between two consecutive points to obtain values corresponding to the data gaps between points; in practice, these discrete instrumented points could be tens of meters apart, at depths corresponding to different soil layers, and hence simple interpolation between the measurement points remains questionable. The Brillouin optical time-domain reflectometry fiber optic strain sensing system is able to provide distributed strain sensing along the entire length of the cable, enabling the full strain profile to be measured during a maintained pile load test. The strain data can also be integrated to obtain the displacement profile. This paper presents three case studies which investigate the performance of three concrete bored piles in London using both conventional vibrating wire strain gauges and distributed fiber optic strain sensing during maintained pile load tests, which enable comparisons made between the two instrumentation systems. In addition, finite-element analyses show that the ability to measure the full strain profiles for each pile is highly advantageous in understanding the performance of the pile and in detecting any abnormalities in the pile behavior.

This paper presents a case study of an Osterberg-cell test of a pile located at the Isle of Dogs in London, which was heavily instrumented with distributed optical-fibre sensors, strain gauges, displacement transducers and extensometers. Special emphasis is given on the data from fibre optics, which offers an advantage due to their spatially continuous nature. The data show a clear development of shaft friction with the applied load and also some unexpected pile–soil slip within two of the soil layers, which is attributed to the development of a filter cake due to the long construction time. Relevant finite-element analyses are also conducted in an attempt to further understand the mechanisms of pile–soil slip, which highlight its importance in predicting the vertical displacements. Finally, some comments are included on the observed behaviour of the founding chalk layer.

This paper discusses several considerations related to appropriate numerical modelling of the reservoir hydrodynamic pressures on dams. The reservoir is modelled with 8-noded isoparametric displacement based solid finite elements. The study includes both stiff and flexible dams with vertical and sloped upstream faces under ramp, harmonic and random acceleration loads. The numerical results were compared and found to be in good agreement with available closed-form solutions. The same approach may be used in analyses of other waterfront structures such as quay walls

The objective of this study is to investigate the effects of dam–reservoir interaction (DRI) on the nonlinear seismic response of earth dams. Although DRI effects have for long been considered as insignificant for earth dams, that conclusion was mainly based on linear elastic investigations which focused only on the acceleration response of the crest without examining the seismic shear stresses and strains within the dam body. The present study explores further the impact of DRI focusing on the nonlinear behavior of earth dams. The effects of reservoir hydrodynamic pressures are investigated in terms of both seismic dam accelerations and nonlinear dynamic soil behavior (seismic shear stresses and strains). It is shown that although dam crest accelerations are indeed insensitive to DRI, the stress and strain development within the dam body can be significantly underestimated if DRI is ignored.