| 1. |
- Karlsson, Freddie, et al.
(författare)
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Dynamic response of driven end-bearing piles and a pile group in soft clay : an experimental validation study
- 2022
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Ingår i: Engineering structures. - : Elsevier BV. - 0141-0296 .- 1873-7323. ; 267
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents novel measurement data on the dynamic soil-structure interaction of an end-bearing pile foundation. The purpose is to assess the ability to predict the foundation impedances based on the small-strain properties of the soil obtained from site investigations. Measurements were performed in two stages of construction, allowing to assess interaction between the piles through the soil. First, single pile impedances and interaction factors between the piles were experimentally obtained for the four piles when they were free to move at the surface. Second, the impedances of the square pile group were measured after casting a concrete pile cap. The piles were additionally instrumented with accelerometers at depth along the centerline of each pile, allowing to illustrate the global behaviour of the piles within the soil. Numerical predictions based solely on information of the small-strain soil properties obtained from extensive site investigations are compared to the experimental results. The impedances of the individual piles are overestimated compared to the measurements, while the interaction factors show a better agreement. The pile group impedances are better captured than the individual ones, using the same soil model. The pile-soil-pile interaction is clearly manifested in the experimental results by pronounced peaks in the pile group vertical impedance, validating results from previous numerical studies.
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| 2. |
- Theland, Freddie, et al.
(författare)
-
Assessment of small-strain characteristics for vibration predictions in a Swedish clay deposit
- 2021
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Ingår i: Soil Dynamics and Earthquake Engineering. - : Elsevier BV. - 0267-7261 .- 1879-341X. ; 150
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Tidskriftsartikel (refereegranskat)abstract
- Environmental vibrations induced by human activities such as traffic, construction or industrial manufacturing can cause disturbance among residents or to vibration sensitive equipment in buildings. In Sweden, geological formations of soft clay overlying a stiff bedrock are soil conditions prone to ground vibrations that are encountered both in urban areas and along parts of the national railway network. This paper presents an extensive investigation of the small-strain soil properties for the prediction of environmental ground vibrations in a shallow clay where the bedrock is situated at 7.5 m depth. The small-strain properties are estimated using available empirical correlations, bender elements, seismic cone penetration tests, seismic refraction and inversion of surface wave dispersion and attenuation curves. The results are synthesised into a dynamic layered soil model which is validated by measurements at the soil's surface at source-receiver distances up to 90 m in the frequency range 1-80 Hz. Analyses of uncertainties in the estimated values of wave speeds and material damping are performed by model investigations, indicating that surface wave tests overestimate the damping compared to bender element tests. The properties of the topmost unsaturated part of the soil is found to have a significant influence on the response at large distances, caused by critically refracted P-waves resonating in the top layer.
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