A field measurement was conducted on an H-pile driven into a multilayer soil profile to analyze the axial stresses/forces generated on the pile during bridge construction activities. Vibrating wire strain gauges and piezometers were utilized, and dynamic testing was conducted for this purpose. Measurements revealed that the pile's pre-installation and temperature changes after installation in cooler ground caused shifts in strain gauge readings. Furthermore, driving an adjacent pile into the vicinity equivalent to four pile diameters, caused a notable increase in pore water pressure, resulting in decreased stresses on the pile. Concreting on top of the pile induced compressive stress during the first day, followed by a considerable decrease and development of tension on the pile over the next two days. Considering the residual force due to pile installation, force distribution, neutral plane location, and maximum axial force along the shaft were different and higher than in the case where this force was ignored. This paper presents a robust methodology to evaluate forces/stresses in a pile subject to installation through to final loading, including drag force effects based on instrumentation measurements. This novel approach provides a better understanding of drag force impacts on actual load capacity under final production loading.

The influence of bitumen coating on the development of unit shaft resistance along driven steel and precast concrete piles resulting from subsiding surrounding soft soil (gyttja) induced by fill placement at terrain was investigated. All piles were instrumented with conventional discrete-point vibrating wire strain gauges and distributed fibre optic sensors to achieve high-resolution strain measurements. The magnitude of the mobilised unit shaft resistance along uncoated piles was observed to be primarily related to an increase in effective stress resulting from the dissipation of excess pore water pressures. The unit shaft resistance along bitumen-coated piles was found to be primarily related to the rate of relative movement between pile and soil, which highlights the effectiveness of bitumen coating in reducing shaft resistance.

For the problem of suffosion in gap-graded sand with initial anisotropy, the Ganser drag force model, which can take into account the effect of the projected area of particles, is introduced to achieve a two-phase coupling of computational fluid dynamics (CFD) and discrete elements method (DEM) for non-spherical particles. The applicability of the numerical method in solving the interaction between the non-spherical particles and fluid is verified by comparing with single particle settlement tests. On this basis, specimens with different bedding orientations and fine contents are further generated to simulate upward seepage suffosion tests, during which both macroscopic and microscopic properties, such as the fine loss, composition of strong and weak force chains, and changes in grain fabric, are monitored to explore the seepage suffosion characteristics of anisotropic soils with various fabrics under different filling states (underfilled and overfilled). Drained triaxial tests are carried out on specimens before and after erosion to investigate the effect of seepage on the weakening of soil strength. The results show that the mass loss of the overfilled specimens increases with increasing deposition angle, while the mass loss of the underfilled specimens firstly increases and then decreases with the deposition angle. The loss of fines in the underfilled specimens is mainly due to the low connectivity fines, whereas for the overfilled specimens, suffosion leads to a simultaneous reduction in the number of both low and high connectivity fines. In addition, the triaxial tests show that suffusion causes a significant weakening of the peak strength of the soil, and the change in peak strength with the deposition angle is also influenced by the soil filling state.