The role of soil stiffness non-linearity in 1D pile driving simulations

Abstract

Drivability studies and determination of pile static capacity from driving resistance are an integral part of present foundation engineering practice. The success of both pile driving simulations and backcalculation of static resistance from pile driving resistance (signal matching analyses) depends on the model used for the interaction of the shaft and base of the pile with the soil. In this paper, a set of advanced base and shaft dynamic reaction models is formulated that accounts explicitly for soil stiffness non-linearity. Comparisons between predictions of the proposed soil reaction models and of various existing reaction models used in practice with measured pile driving data from two wellinstrumented field cases allow assessment both of the importance of stiffness non-linearity in accurate pile driving simulations and of the usefulness of various levels of sophistication in the shaft and base reaction models.

Full-scale observations of dynamic and static axial responses of offshore piles driven in chalk and tills

“…In both models, the primary input parameters of shaft and base resistance, soil density and shear modulus are linked to measurable soil properties. The values of G were secant values, G1 degraded from the small strain, Gmax values to account indirectly for soil non-linearity, following Alves et al (2009) and Salgado et al (2015). In the Holocene and glacial till, the best matches were obtained taking G1 close to 200 'v0, following the recommendations of Lee et al (1988) for sandy soils, which resulted in G1/Gmax ratios of <0.3.…”

Pile driveability in low- to medium-density chalk

“…Several rheological models have been proposed to better simulate the mechanics of pile driving (e.g. Deeks and Randolph, 1995, Holeyman, 1985, Randolph and Simons, 1986, Salgado et al, 2015. The signal matching described in this study employed the research-oriented software IMPACT (Randolph, 2008) which utilises the method of characteristics (De Josselin de Jong, 1956) as a numerical method along with the Randolph and Simons (1986) resistance model for the shaft and the Deeks and Randolph (1995) model at the base.…”

“…The soil density, s and shear moduli, G, taken for the cases considered below were determined from local site investigations. Operational secant stiffnesses, G1 were scaled down from the measured small-strain, Gmax values to account for soil non-linearity as recommended by Alves et al (2009) and Salgado et al (2015). The best matches for the Wikinger glacial till were obtained taking G1=200'vo following Lee et al (1988) for sandy soils, which resulted in G1/Gmax ratios of <0.3, while G1<0.2Gmax was assumed to model the Wikinger and SNW chalks.…”

Displacement Estimation Error in Laser Scanning Monitoring of Retaining Structures Considering Roughness

“…The lateral movement of the ground can be suppressed by being used with reinforcement methods, such as anchors and soil nailing in concrete panels [1][2][3][4][5][6][7][8]. The resistance between soil and grouting can be generated during the movement of soil [9][10][11]. If the displacement of the ground has a great influence on the stability of the entire construction, a retaining structure can be installed before excavation.…”